- Email: [email protected]
In vitro fertilization add-ons for the endometrium: it doesn’t add-up
In vitro fertilization add-ons for the endometrium: it doesn’t add-up Sarah Lensen, Ph.D.,a Norman Shreeve, B.M.B.S.,b Kurt T. Barnhart, M.D., M.S.C.E,c Ahmed Gibreel, M.D.,d Ernest Hung Yu Ng, M.D.,e and Ashley Moffett, M.D.f a Department of Obstetrics and Gynaecology, University of Auckland, New Zealand; b Department of Obstetrics & Gynaecology, Addenbrooke's Hospital, Cambridge, United Kingdom; c Department of Obstetrics and Gynecology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; d Department of Obstetrics & Gynaecology, Mansoura University, Mansoura, Egypt; e Department of Obstetrics & Gynecology, The University of Hong Kong, Hong Kong; and f Department of Pathology and Centre for Trophoblast Research, University of Cambridge, Cambridge, United Kingdom
The probability of live birth from an in vitro fertilization (IVF) cycle is modest. Many additional treatments (add-ons) are available which promise to improve the success of IVF. This review summarizes the current evidence for common IVF add-ons which are suggested to improve endometrial receptivity. Systematic reviews of randomized controlled trials and individual trials were included. Five add-ons were included: immune therapies, endometrial scratching, endometrial receptivity array, uterine artery vasodilation, and human chorionic gonadotropin instillation. The results suggest there is no robust evidence that these add-ons are effective or safe. Many IVF addons are costly, consuming precious resources which may be better spent on evidence-based treatments or further IVF. Large randomized controlled trials and appropriate safety assessment should be mandatory before the introduction of IVF add-ons into routine practice. (Fertil SterilÒ 2019;112:987–93. Ó2019 by American Society for Reproductive Medicine.) Key Words: IVF add-on, treatment add-on, adjuvant, IVF adjunct Discuss: You can discuss this article with its authors and other readers at https://www.fertstertdialog.com/users/16110-fertilityand-sterility/posts/51850-28708
T
here is a plethora of adjunct or add-on interventions available to patients undergoing in vitro fertilization (IVF). Despite very few add-ons having any robust evidence of effectiveness or safety, their use is believed to be widespread (1). As the use of IVF add-ons is essentially unregulated, there are limited data available on worldwide prevalence; however, for example, it is estimated that 74% of women undergoing IVF in the U.K. used one or more add-ons in 2018 (2). Add-ons include many different interventions, including those suggested to increase the follicular response to ovarian stimulation, improve the culture conditions and quality of devel-
oping embryos, or prime the endometrium for impending implantation. Despite improvements in IVF technology over time, pregnancy rates have generally plateaued and high quality euploid embryos often fail to implant. Many IVF patients are being faced with a diagnosis of recurrent implantation failure after several repeated unsuccessful embryo transfers. These observations have led to an increased focus on the role of the endometrium in implantation (3, 4). As such, several add-ons have appeared on the market with the promise that they will improve the receptivity of the endometrium and increase the probability of live birth. The aim of this review is to summarize
Received July 31, 2019; revised September 28, 2019; accepted October 4, 2019. S.L. has nothing to disclose. N.S. has nothing to disclose. K.T.B. has nothing to disclose. A.G. has nothing to disclose. E.H.Y.N. has nothing to disclose. A.M. has nothing to disclose. Correspondence: Sarah Lensen, Ph.D., Department of Obstetrics and Gynaecology, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand (E-mail: [email protected]). Fertility and Sterility® Vol. 112, No. 6, December 2019 0015-0282/$36.00 Copyright ©2019 American Society for Reproductive Medicine, Published by Elsevier Inc. https://doi.org/10.1016/j.fertnstert.2019.10.011 VOL. 112 NO. 6 / DECEMBER 2019
the available evidence for common IVF add-ons proposed to enhance endometrial receptivity.
METHODS A long list of add-ons was compiled from those included in recent reviews (1, 5, 6). We then selected the add-ons suggested to improve endometrial receptivity specifically and merged similar add-ons into broader categories (for example, intralipid and corticosteroids are both considered under the add-on immune therapies). We then searched for Cochrane systematic reviews of randomized controlled trials (RCTs) assessing these add-ons. In general, Cochrane reviews have been demonstrated as higher quality and less biased than other systematic reviews (7, 8). If no Cochrane review was available, or the review was published before 2016 and may therefore be out of date, we expanded the search to recent systematic reviews of RCTs published in any journal (PubMed, last search June 2019). 987
VIEWS AND REVIEWS When no systematic review was available for a specific addon, we then searched for individual RCTs. We did not consider evidence from non-randomized trials (e.g. cohort, observational or case-control studies) as this evidence is prone to bias and does not provide robust evidence of safety or effectiveness. For each add-on, the current rating assigned by the UK Human Fertilisation and Embryology Authority (HFEA) was captured. Green is assigned where more than one good quality RCT has demonstrated the add-on to be effective and safe, amber is assigned in the case of conflicting evidence, and red when there is no evidence of effectiveness and safety (5). The HFEA has rated a total of 11 add-ons, and not all addons reviewed here have been rated at the time of this review. Costs of each add-on were obtained from the literature, internet searching and review of clinic websites. Institutional Review Board approval was not obtained as this is a literature review only.
RESULTS We identified five IVF add-ons suggested to improve endometrial receptivity: immune therapies, endometrial scratching, endometrial receptivity array (ERA), uterine artery vasodilation and human chorionic gonadotropin (hCG) instillation. For three add-ons, we reviewed a recent Cochrane review (endometrial scratching, vasodilators and hCG instillation), for another a recent non-Cochrane review (immune therapies), and for one add-on only an interim analysis of an RCT was available (ERA).
Immune therapies There is a common belief that the maternal immune system is damaging in early pregnancy and needs suppressing (9, 10). However, there is no high-quality evidence to support this notion, and the classical features of inflammation are not seen in decidua in early pregnancy (11). The immune cells allegedly responsible for implantation failure are specialized uterine natural killer cells (uNK). This unfortunate nomenclature gave rise to the idea that NK cells attack the fetus, causing implantation failure and pregnancy loss. NK cells circulating in peripheral blood are indeed cytotoxic to virally-infected or cancerous cells. However, uNK are phenotypically and functionally quite distinct from those in blood and only come into contact with placental trophoblast cells, not the fetus (12). Indeed, uNK cannot kill trophoblast in vitro (13). Despite these findings, there has been a dramatic rise in the use of assays and therapies devised to detect and remedy supposed immunological aberrations in the endometrium; such add-ons were used by 8% of UK couples accessing IVF in 2018 (2). Below we summarize four common immune therapies offered as addons to IVF, all of which, despite lack of any clear biological rationale, have been proposed to dampen the inflammatory and immune state of the endometrium and thereby increase the probability of implantation and pregnancy. Corticosteroids. Corticosteroids such as prednisolone are prescribed for the treatment of inflammatory conditions such as systemic lupus, erythematosus and rheumatoid arthritis. They are also commonly offered to IVF patients 988
near the time of embryo transfer. A Cochrane meta-analysis of 14 studies concluded that peri-implantation glucocorticoids provided no clear benefit in terms of live birth or pregnancy rate (14). These findings were corroborated more recently in additional systematic reviews (15, 16). Whilst the use of corticosteroids in patients with autoantibodies requires further investigation, there is sufficient evidence to recommend against the routine use of peri-implantation glucocorticoids for IVF (15). Furthermore, the safety of corticosteroids for the developing conceptus has not been studied robustly, and risks for the developing fetus are a concern. Observational studies reported possible causal associations between peri-implantation and first trimester corticosteroid exposure and the risk of oral cleft, major congenital anomalies, prematurity, and low birth weight (17). Indeed, the U.S. FDA has assigned a Category D rating to prednisolone due to evidence of adverse drug reactions for the fetus. Prednisolone is a cheap intervention, costing less than US$10 per IVF cycle (13, 18). Intravenous immunoglobulin. Intravenous immunoglobulin (IVIG) is an important therapy in diverse autoimmune and inflammatory disorders, as well as primary immunodeficiencies. Its effects on the systemic immune system are complex and how it might affect the uterine immune system is completely unknown (19). A recent systematic review included two small trials evaluating the application of IVIG during ovarian stimulation or near the time of embryo transfer, and reported no clinical benefit (15, 20, 21). IVIG requires administration in a supported medical environment as known adverse reactions include tachycardia, thromboembolic complications, and anaphylactic reactions (22). As such, the UK Department of Health does not recommend IVIG for IVF failure (23). Further, IVIG is an expensive therapy, costing US$2000 to $14,000 per IVF cycle (24-27). Granulocyte-Colony Stimulating Factor (G-CSF). Granulocyte-colony stimulating factor (G-CSF) is a cytokine secreted by immune cells such as macrophages, and recombinant human G-CSF is commonly used to treat hematological conditions such as neutropenia. G-CSF can be administered as an intrauterine instillation or subcutaneous injection near the time of embryo transfer, often in women with thin endometrium or recurrent implantation failure. The rationale for its use in IVF is not clear, and it comes at the cost of approximately US$100 to $599 (12, 28). Only a Cochrane protocol is available, and the review is currently in progress. Other recent systematic reviews identified 10 RCTs and reported possible benefit from G-CSF perfusion on the probability of clinical pregnancy (15, 29, 30). However, as many of the included trials lacked clear descriptions of randomization, were heterogeneous, and did not measure live birth, there is insufficient evidence to recommend for or against the use of G-CSF in practice (15). Intralipid. Intralipid is an emulsion of soy bean oil, egg phospholipids and glycerin, commonly administered as intravenous nutrition for patients not able to tolerate an oral diet. Intralipid is thought to also modulate immune function and has been observed to reduce the probability of spontaneous abortion in a mouse model (31). A systematic review VOL. 112 NO. 6 / DECEMBER 2019
Fertility and Sterility® identified only a single trial: a double-blind RCT which found that giving intralipid to women with ‘elevated NK cell levels’ did not improve chemical pregnancy rate (15, 32). This add-on costs approx. US$300 (33-35). While intravenous fat emulsion infusions are generally well tolerated, complications such as jaundice and hyperthermia have been reported (36). Additionally, there are examples of serious adverse events; immune therapies were considered to have contributed to the demise of a twin pregnancy at 23 weeks, following the development of severe systemic candidiasis (37). Reproductive immunology testing and treatment is currently rated red by the HFEA.
Endometrial scratching Endometrial scratching is a technique used to disrupt or injure the endometrium, commonly through the action of a pipelle biopsy, a routine gynecological procedure used for detecting possible intrauterine pathologies. The procedure is often performed in the luteal phase of the cycle prior to IVF (38). The resulting inflammation and activation of immune pathways is suggested to improve the receptivity of the endometrium to an implanting embryo, and although a number of other theories have also been put forward (39, 40), the biological plausibility of endometrial scratching has been questioned. It is difficult to conceive how any beneficial effect is retained when the entire functional layer of the endometrium is shed and replaced between the intervention and embryo implantation (41). This procedure has been subject to intense global interest and was the most common IVF add-on offered to fertility patients in the UK in 2016 (1). In 2018 endometrial scratching was used in 27% of IVF cycles in the UK (2). Over 80% of clinicians in a survey across New Zealand, Australia and the UK reported to recommend this procedure to their patients, at a cost of between USD $65 - $500 (38). The Cochrane review on this topic is currently being updated. Evidence from the previous update included 14 RCTs and reported possible benefit from endometrial scratching before IVF, with subgroup analysis suggesting the procedure may only help women with recurrent implantation failure (42). More recently, similar conclusions have been reported by a number of systematic reviews (43-45). Today, there have been over 30 trials published on this topic, and more are coming. Despite the wealth of clinical trial data, the information remains difficult to interpret: reported effects from endometrial scratching range from implausible benefit to significant harm (46, 47). The results of a large trial of more than 1,300 women was recently published which reports no benefit from endometrial scratching in women undergoing IVF, and subgroup analysis did not identify any subgroup of women who might benefit (48). While some researchers consequently call for abandoning scratching (49), others suggest certain (undefined) subgroups of women may still benefit from this procedure (50, 51). Endometrial biopsy has an established safety profile and adverse reactions are uncommon (e.g. vasovagal reaction, infection). However, the procedure is somewhat painful. In the available trials, patients reported pain scores between 3– 7 of 10, and the procedure was discontinued due to pain in VOL. 112 NO. 6 / DECEMBER 2019
a number of cases (46, 48, 52, 53). This add-on is currently rated amber by the HFEA.
Endometrial Receptivity Array The ERA is a novel diagnostic test based on microarray technology, created by a commercial enterprise. The test requires an appropriately timed endometrial biopsy to measure the endometrial expression of 248 genes (54). A sophisticated prediction model is then applied to categorize the endometrium as one of: receptive, pre-receptive, or proliferative. This categorization then enables women to undergo a personalized embryo transfer, where the exact timing of the transfer has been tailored to each woman’s personal window of implantation. The test has repeatedly demonstrated that women with recurrent implantation failure are more likely to suffer from a non-receptive endometrium, and approximately 25% of women with recurrent implantation failures are reported to have a displaced implantation window. Additionally, the test applied to the same women biopsied in multiple cycles will consistently produce the same result (54, 55). However, to date, only a single RCT has been completed, for which only interim and per-protocol analyses are available (56, 57). It is therefore not possible to confirm whether or not the ERA increases the probability of live birth. Despite lack of any robust evidence of benefit from RCTs, the ERA is widely used by IVF centers around the world; more than 55,000 ERA tests have been conducted in 60 countries (58). Evaluation of the ERA by external researchers is required to provide independent evidence evaluating this add-on, as has been suggested by others (59). However, at the cost of US$800 per test (28, 60), an adequately powered RCT recruiting >1,000 women would require $400,000 USD to cover the ERA cost alone. The ERA test requires an endometrial biopsy, necessitates a freeze-all cycle and repeated medicated cycles to enable ERA biopsy followed by personalized embryo transfer. As such, adverse events associated with endometrial biopsy, and the implications of delays and costs incurred by freeze-all and repeated cycles, should also be considered. This add-on is not currently rated by the HFEA.
Uterine artery vasodilation Vasodilators cause widening of blood vessel lumen and increased blood flow and are commonly used to treat conditions such as hypertension and erectile dysfunction. Thin endometrium, often defined as less than 7 or 8 mm, is associated with reduced probability of pregnancy during an IVF cycle (61, 62). Vasodilators such as sildenafil are therefore suggested to cause uterine vascular relaxation, increasing blood flow to the uterus and endometrium resulting in thickened endometrium and improved endometrial receptivity. If beneficial, such treatment would likely be costeffective as the cost of sildenafil is approximately US$20 per dose (18). A recent Cochrane review included 15 trials evaluating vasodilators in women undergoing IVF (63). The results report increased endometrial thickness to be associated with the use of vasodilators and suggest they 989
VIEWS AND REVIEWS may increase the chance of pregnancy in women undergoing IVF; however, the effect on live birth is unclear as only a small number of trials reported this outcome. Additionally, vasodilators were associated with increased adverse events such as headache and tachycardia. Indeed, sildenafil is associated with numerous drug reactions, including flushing, headache, abnormal vision, and insomnia (64). There are several other interventions proposed to increase endometrial thickness, such as aspirin and platelet-rich plasma. These add-ons are not specifically covered in this review, however recent guidelines suggest there is minimal evidence to support the use of these (65).This add-on is not currently rated by the HFEA.
these systematic reviews suffered from serious risk of bias, such as lack of blinding, no clear description of randomization and allocation concealment, premature termination of the study following (often unplanned) interim analysis, and lack of prospective trial registration. Additionally, the majority of trials contributing to the evidence-base summarized here recruited too few women to have enough statistical power to detect clinically relevant effect sizes, as is common in our field (70). For example, in the case of endometrial scratching, two thirds of trials reporting live birth recruited 200 women or fewer. A trial of 200 women would only be powered to detect an impressive and unrealistic improvement from IVF add-ons of 20 percentage points (e.g. from 25% to 45%, at 80% power and 5% significance level).
Intrauterine human chorionic gonadotropin Human chorionic gonadotropin is a hormone produced during pregnancy and is believed to regulate embryo implantation. hCG is often used during an IVF cycle to trigger final oocyte maturation, and costs approximately US$40 (18). Intrauterine infusion of hCG has been shown to upregulate cytokines known to be involved with implantation (66, 67). Injection or instillation of hCG into the uterine cavity prior to embryo transfer is therefore suggested to increase the probability of successful implantation by ensuring sufficient levels of hCG are present. A recent Cochrane review identified 17 RCTs (68). The authors observed high heterogeneity between trials and were therefore unable to pool the trials overall. However, in subgroup analyses it appears that among women undergoing cleavage stage embryo transfer, an hCG dose of R 500 IU increases the probability of clinical pregnancy and live birth. As this finding was only observed in a subgroup analysis, current evidence does not support the use of hCG injection in routine practice. This add-on is not currently rated by the HFEA.
Quality of the evidence Three of the five included add-ons (endometrial scratching, vasodilators, and hCG instillation) were evaluated by Cochrane reviews, which include a Grading of Recommendations, Assessment, Development and Evaluation (GRADE) assessment of the quality of evidence (69). In all cases, the quality of evidence varied between very low to moderate quality; in no case was the evidence found to be high quality. The Cochrane authors downgraded the evidence for risk of bias, imprecision, and inconsistency. For example, an Egyptian trial of endometrial scratching prior to IVF reported a live birth rate of 67% after endometrial scratching compared to 28% in the control group; producing an odds ratio 4.88 (95% confidence interval 3.22-7.40) in favor of endometrial scratching (46). Such a large effect size, and a live birth rate of 67%, is highly improbable. The heterogeneity of trial results observed by many of the included systematic reviews may arise in part due to differences in methodology between trials or the populations recruited. A more likely explanation may be poor quality of the included trials. Indeed, many of the studies included in 990
DISCUSSION This review summarizes the available evidence for common IVF add-ons proposed to improve endometrial receptivity and increase the probability of implantation and pregnancy. While there is weak evidence to suggest vasodilators and GCSF may offer increased probability of pregnancy in some women, heterogeneity, risk of bias and lack of data for live birth preclude recommendations for the routine use of any of these add-ons. Therefore, available evidence suggests the add-ons summarized here lack robust evidence, and should only be offered in experimental settings, namely randomized controlled trials. Unfortunately, these add-ons are already in routine use. The availability is not niche or restricted to a select few clinics; 74% of patients attending fertility clinics in the UK received one or more add-ons in 2018 (2). There appears to be a clear propensity for clinicians to provide costly IVF add-ons with no robust evidence base. Indeed, the ERA is used by IVF centers around the world; however, results are not yet available from a single (completed) RCT. The explanation for this is probably multifactorial. A likely contributor is the poor quality of the original primary research, much of which appears to demonstrate benefit from new IVF addons, which cannot be confirmed by subsequent trials. Many add-on treatments have been offered to patients as potentially promising therapies, followed by calls for robust evaluation by RCTs. Additionally, there is no clear incentive for companies to produce high-quality RCT evidence which may risk disproving their claims. Academics and researchers without appropriate expertise or experience are free to conduct small, biased, RCTs, and to publish these in peer reviewed journals, often despite lack of adequate trial registration. We repeat sentiments published 25 years ago ‘‘much poor research arises because researchers feel compelled for career reasons to carry out research that they are ill equipped to perform, and nobody stops them’’ (71). There appears to be little consideration for biological plausibility in the innovation of new add-ons, which often appear to be based on a misunderstanding of the science of implantation. Intralipid started out as a placebo: due to its similar appearance, intralipid was used as the control treatment in the evaluation of immunotherapy using syncytiotrophoblast membranes (cited in [32]). There is no clear rationale VOL. 112 NO. 6 / DECEMBER 2019
Fertility and Sterility® to support the transition of intralipid from an inert placebo to a common IVF add-on. The development of add-ons devised to improve endometrial receptivity should be based on a thorough understanding of the molecular and cellular events occurring at implantation. Increased collaboration between clinicians, reproductive biologists and immunologists may lead to better progress. Clinicians are also driven by a genuine desire to increase pregnancy rates, and the ability to offer couples something ‘extra’ when faced with multiple failed attempts. In the case of poor prognosis or previous IVF failure, clinicians may view any additional intervention as possibly beneficial to the patient, who is otherwise very unlikely to conceive. However, in an increasingly commercialized sector, motivations also risk being driven by marketing and financial gain, to offer something your competitors do not. Such conflicts of interest are especially dangerous in the context of a vulnerable population who may do (and pay) whatever it takes. Clinicians recommending add-ons should also consider the risk of harm. However, one cannot easily make an informed assessment of benefit vs. harm when the evidence for benefit is poor, and that for harm is even worse. Most of the trials investigating these interventions fail to report adverse events, and rare but serious harms may be difficult to detect. For example, there is special concern of congenital anomalies and prematurity from glucocorticoid exposure in pregnancy (17); any actual increased risk in the context of peri-implantation exposure could only be assessed through large cohort or case-control studies (which have not been performed). Other harms may seem less serious but should not be overlooked, including known adverse side-effects, costs to patients, and the potential psychological harms of offering false hope. There are several limitations to this review which should be noted. Firstly, this was not a systematic literature review and did not rely on a comprehensive search of the primary literature; therefore, relevant publications may have been missed. We only included add-ons deemed to be in common use, and those discussed here are not exhaustive; for example other available immune therapies include TNF-a blockers (72), tacrolimus (73), and intrauterine injection of peripheral blood mononuclear cells (74). Further, much of the evidence regarding cost comes from certain countries including the UK, U.S. and Australia, and prices have been converted to the USD equivalent. These figures only provide a guide as information about cost was not collected systematically and may vary substantially in different settings.
CONCLUSION This review summarizes the current evidence for common IVF add-ons which are suggested to improve endometrial receptivity: immune therapies, endometrial scratching, endometrial receptivity array, uterine artery vasodilation and human chorionic gonadotropin instillation. The results suggest there is no robust evidence that these add-ons are effective or safe. Many IVF add-ons are costly, consuming precious resources which may be better spent on evidenceVOL. 112 NO. 6 / DECEMBER 2019
based treatments or further IVF. Large RCTs and appropriate safety assessment should be mandatory before the introduction of IVF add-ons into routine practice.
REFERENCES 1.
2.
3.
4.
5.
6. 7.
8.
9.
10.
11.
12. 13.
14.
15.
16.
17.
18. 19. 20.
21.
Spencer EA, Mahtani KR, Goldacre B, Heneghan C. Claims for fertility interventions: a systematic assessment of statements on UK fertility centre websites. BMJ Open 2016:1–6. Human Fertilisation and Embryology Authority. The National Fertility Patient Survey; 2018. Available at: https://www.hfea.gov.uk/media/2702/pilotnational-fertility-patient-survey-2018.pdf. Emerging role for dysregulated decidualization in the genesis of preeclampsia. In: Conrad KP, Rabaglino MB, Uiterweer Post, editors. Placenta 2017;60: 119–29. Garrido-Gomez T, Dominguez F, Quinonero A, Diaz-Gimeno P, Kapidzic M, Gormley M, et al. Defective decidualization during and after severe preeclampsia reveals a possible maternal contribution to the etiology. Proc Natl Acad Sci U S A 2017;114:E8468–77. Human Fertilisation and Embryology Authority. Treatment add-ons. 2018. Available at: https://www.hfea.gov.uk/treatments/explore-all-treatments/ treatment-add-ons/. Datta AK, Campbell S, Deval B, Nargund G. Add-ons in IVF programme hype or hope? Facts Views Vis Obgyn 2015;7:241–50. Goldkuhle M, Narayan VM, Weigl A, Dahm P, Skoetz N. A systematic assessment of Cochrane reviews and systematic reviews published in high-impact medical journals related to cancer. BMJ Open 2018;8:e020869. Jørgensen AW, Hilden J, Gøtzsche PC. Cochrane reviews compared with industry supported meta-analyses and other meta-analyses of the same drugs: systematic review. BMJ 2006;333:782. Yamada H, Morikawa M, Kato EH, Shimada S, Kobashi G, Minakami H. Preconceptional natural killer cell activity and percentage as predictors of biochemical pregnancy and spontaneous abortion with normal chromosome karyotype. Am J Reprod Immunol 2003;50:351–4. Sacks G, Yang Y, Gowen E, Smith S, Fay L, Chapman M. Detailed analysis of peripheral blood natural killer cells in women with repeated IVF failure. Am J Reprod Immunol 2012;67:434–42. Vento-Tormo R, Efremova M, Botting RA, Turco MY, Vento-Tormo M, Meyer KB, et al. Single-cell reconstruction of the early maternal-fetal interface in humans. Nature 2018;563:347–53. Moffett A, Shreeve N. First do no harm: uterine natural killer (NK) cells in assisted reproduction. Hum Reprod 2015;30:1519–25. King A, Birkby C, Loke YW. Early human decidual cells exhibit NK activity against the K562 cell line but not against first trimester trophoblast. Cell Immunol 1989;118:337–44. Boomsma CM, Keay SD, Macklon NS. Peri-implantation glucocorticoid administration for assisted reproductive technology cycles. Cochrane Database of Systematic Reviews 2012;6:005996. Practice Committee of the American Society for Reproductive Medicine. The role of immunotherapy in in vitro fertilization: a guideline. Fertil Steril 2018; 110:387–400. Achilli C, Duran-Retamal M, Saab W, Serhal P, Seshadri S. The role of immunotherapy in in vitro fertilization and recurrent pregnancy loss: a systematic review and meta-analysis. Fertil Steril 2018;110:1089–100. Robertson SA, Jin M, Yu D, Moldenhauer LM, Davies MJ, Hull ML, et al. Corticosteroid therapy in assisted reproduction - immune suppression is a faulty premise. Hum Reprod.2016;31:2164-2173. Herts and Essex Fertility Centre. Price list 2019. Available at: https:// hertsandessexfertility.com/price-list/. Accessed August 1, 2019. Galeotti C, Kaveri SV, Bayry J. IVIG-mediated effector functions in autoimmune and inflammatory diseases. Int Immunol 2017;29:491–8. Stephenson MD, Fluker MR. Treatment of repeated unexplained in vitro fertilization failure with intravenous immunoglobulin: a randomized, placebo-controlled Canadian trial. Fertil Steril 2000;74:1108–13. De Placido G, Zullo F, Mollo A, Cappiello F, Nazzaro A, Colacurci N, et al. Intravenous immunoglobulin (IVIG) in the prevention of implantation failures. Ann N Y Acad Sci 1994;734:232–4. 991
VIEWS AND REVIEWS 22. 23.
24. 25. 26.
27. 28. 29.
30. 31. 32.
33.
34. 35. 36.
37.
38. 39.
40.
41.
42.
43.
44.
45.
992
Katz U, Achiron A, Sherer Y, Shoenfeld Y. Safety of intravenous immunoglobulin (IVIG) therapy. Autoimmun Rev 2007;6:257–9. Department of Health and Social Care. Clinical guidelines for immunoglobulin use (second edition update); 2011. Available at: https://assets. publishing.service.gov.uk/government/uploads/system/uploads/attachment_ data/file/216671/dh_131107.pdf. Intravenous immunoglobulin (IVIG) and recurrent spontaneous pregnancy loss. Fertil Steril 2006;86(5 Suppl 1):S226-7. CNY Fertility. IVIG therapy. 2019. Available at: https://www.cnyfertility.com/ ivig-therapy/. Accessed July 1, 2019. Braverman IVF & Reproductive Immunology. IVIG treatment for miscarriages. 2019. Available at: https://www.preventmiscarriage.com/intravenousimmunoglobulin-ivig-.html. Accessed July 1, 2019. LA IVF. Intravenous imunoglobulin (IVIG) for IVF. 2019. Available at: https:// laivfclinic.com/intravenousimmunoglobulin/. Accessed July 1, 2019. Fertility North. Fees. 2019. Available at: http://www.fertilitynorth.com.au/ fees/. Accessed July 1, 2019. Zhang L, Xu WH, Fu XH, Huang QX, Guo XY, Zhang L, et al. Therapeutic role of granulocyte colony-stimulating factor (G-CSF) for infertile women under in vitro fertilization and embryo transfer (IVF-ET) treatment: a meta-analysis. Arch Gynecol Obstet 2018;298:861–71. Li J, Mo S, Chen Y. The effect of G-CSF on infertile women undergoing IVF treatment: a meta-analysis. Syst Biol Reprod Med 2017;63:239–47. Clark DA. Intralipid as treatment for recurrent unexplained abortion? Am J Reprod Immunol 1994;32:290–3. Dakhly DM, Bayoumi YA, Sharkawy M, Gad Allah SH, Hassan MA, Gouda HM, et al. Intralipid supplementation in women with recurrent spontaneous abortion and elevated levels of natural killer cells. Int J Gynaecol Obstet 2016;135:324–7. Heneghan C, Spencer EA, Bobrovitz N, Collins DRJ, Nunan D, Pl€ uddemann A, et al. Lack of evidence for interventions offered in UK fertility centres. BMJ 2016;355. The Fertility & Gynaecology Academy. Fees. 2019. Available at: https:// www.fertility-academy.co.uk/fees/. Accessed July 1, 2019. The Fertility & Gynaecology Academy. Our fees. 2019. Available at: https:// argc.co.uk/our-fees/. Accessed July 1, 2019. Hansen LM, Hardie BS, Hidalgo J. Fat emulsion for intravenous administration: clinical experience with intralipid 10%. Ann Surg 1976;184: 80–8. Akhanoba F, MacDougall J, Mathur R, Hassan W. Severe systemic candidiasis following immunomodulation therapy in in vitro fertilisation-embryo transfer (IVF-ET). BMJ Case Rep 2014;2014. https://doi.org/10.1136/ bcr,2013-203202. Lensen S, Sadler L, Farquhar C. Endometrial scratching for subfertility: everyone's doing it. Hum Reprod 2016;31:1241–4. Zhou L, Li R, Wang R, Huang HX, Zhong K. Local injury to the endometrium in controlled ovarian hyperstimulation cycles improves implantation rates. Fertil Steril 2008;89:1166–76. Gibreel A, El-Adawi N, Elgindy E, Al-Inany H, Allakany N, Tournaye H. Endometrial scratching for women with previous IVF failure undergoing IVF treatment. Gynecol Endocrinol 2015;31:1–4. n C, Bellver J. Scratching beneath 'the Scratching Case': systematic reSimo views and meta-analyses, the back door for evidence-based medicine. Hum Reprod 2014;29:1618–21. Nastri CO, Lensen SF, Gibreel A, Raine-Fenning N, Ferriani RA, Bhattacharya S, et al. Endometrial injury in women undergoing assisted reproductive techniques. Cochrane Database Syst Rev 2015;3:CD009517. Gui J, Xu W, Yang J, Feng L, Jia J. Impact of local endometrial injury on in vitro fertilization/intracytoplasmic sperm injection outcomes: A systematic review and meta-analysis. J Obstet Gynaecol Res 2019;45:57–68. van Hoogenhuijze NE, Kasius JC, Broekmans FJM, Bosteels J, Torrance HL. Endometrial scratching prior to IVF; does it help and for whom? A systematic review and meta-analysis. Hum Reprod Open 2019;2019:1–18. Vitagliano A, Di Spiezio Sardo A, Saccone G, Valenti G, Sapia F, Kamath MS, et al. Endometrial scratch injury for women with one or more previous failed embryo transfers: a systematic review and meta-analysis of randomized controlled trials. Fertil Steril 2018;110:687–702.e2.
46.
47.
48.
49. 50.
51. 52.
53.
54.
55.
56.
57.
58. 59.
60.
61.
62.
63.
64.
65.
Mahran A, Ibrahim M, Bahaa H. The effect of endometrial injury on first cycle IVF/ICSI outcome: A randomized controlled trial. Int J Reprod Biomed 2016; 14:193–8. Karimzade MA, Oskouian H, Ahmadi S, Oskouian L. Local injury to the endometrium on the day of oocyte retrieval has a negative impact on implantation in assisted reproductive cycles: A randomized controlled trial. Arch Gynecol Obstet 2010;281:499–503. Lensen S, Osavlyuk D, Armstrong S, Stadelmann C, Hennes A, Napier E, et al. A randomized trial of endometrial scratching before in vitro fertilization. N Engl J Med 2019;380:325–34. Mol BW, Barnhart KT. Scratching the endometrium in in vitro fertilization time to stop. N Engl J Med 2019;380:391–2. Lensen S, Venetis C, Ng EHY, Young SL, Vitagliano A, Macklon NS, et al. Should we stop offering endometrial scratching prior to in vitro fertilization? Fertil Steril 2019;111:1094–101. Macklon NS, Ahuja KK, Fauser B. Building an evidence base for IVF 'addons'. Reprod Biomed Online 2019;38:853–6. Polanski LT, Baumgarten MN, Richardson A, Sewell K, Brosens JJ, Quenby S, et al. Endometrial biopsy prior to assisted reproductive techniques (ART) does not improve treatment outcome in unselected patients. Hum Reprod Annual Meeting of ESHRE 2015 (O-027). Frantz S, Parinaud J, Kret M, Rocher-Escriva G, Papaxanthos-Roche A, Creux H, et al. Decrease in pregnancy rate after endometrial scratch in women undergoing a first or second in vitro fertilization. A multicenter randomized controlled trial. Hum Reprod 2019;34:92–9. Ruiz-Alonso M, Blesa D, Diaz-Gimeno P, Gomez E, Fernandez-Sanchez M, Carranza F, et al. The endometrial receptivity array for diagnosis and personalized embryo transfer as a treatment for patients with repeated implantation failure. Fertil Steril 2013;100:818–24. Díaz-Gimeno P, Ruiz-Alonso M, Blesa D, Bosch N, Martínez-Conejero JA, Alama P, et al. The accuracy and reproducibility of the endometrial receptivity array is superior to histology as a diagnostic method for endometrial receptivity. Fertil Steril 2013;99:508–17. Simon C, Vladimirov IK, Castillon Cortes G, Ortega I, Cabanillas S, Vidal C, et al. Prospective, randomized study of the endometrial receptivity analysis (ERA) test in the infertility work-up to guide personalized embryo transfer versus fresh transfer or deferred embryo transfer. Fertil Steril 2016;106: e46–7. Simon C, Gomez C, Cabanillas S, Vladimirov IK, Castillon G, Giles J, et al. In vitro fertilization with personalized blastocyst transfer versus frozen or fresh blastocyst transfer: a multicenter, randomized clinical trial. Fertil Steril 2019;112:e56. ERA® Endometrial Receptivity Analysis. 2019. Available at: https://www. igenomix.com/our-services/era/. Accessed November 19, 2019. Cho K, Tan S, Buckett W, Dahan MH. Intra-patient variability in the endometrial receptivity assay (ERA) test. J Assist Reprod Genet 2018;35: 929–30. What to know about endometrial receptivity analysis. 2019. Available at: https://fertility.igenomix.com/blog/what-to-know-about-endometrial-rece ptivity-analysis/. Accessed July 1, 2019. Check JH. The importance of sonographic endometrial parameters in influencing success following embryo transfer in the modern era and therapeutic options–part 1: the importance of late proliferative phase endometrial thickness. Clin Exp Obstet Gynecol 2011;38:197–200. Gonen Y, Casper RF. Prediction of implantation by the sonographic appearance of the endometrium during controlled ovarian stimulation for in vitro fertilization (IVF). J In Vitro Fert Embryo Transf 1990;7:146–52. Gutarra-Vilchez RB, Bonfill Cosp X, Glujovsky D, Viteri-García A, RunzerColmenares FM, Martinez-Zapata MJ. Vasodilators for women undergoing fertility treatment. Cochrane Database of Systematic Reviews 2018. https://doi.org/10.1002/14651858.CD010001.pub3. Moreira SG Jr, Brannigan RE, Spitz A, Orejuela FJ, Lipshultz LI, Kim ED. Sideeffect profile of sildenafil citrate (Viagra) in clinical practice. Urology 2000; 56:474–6. Liu KE, Hartman M, Hartman A. Management of thin endometrium in assisted reproduction: a clinical practice guideline from the Canadian Fertility and Andrology Society. Reprod BioMed Online 2019;39:49–62.
VOL. 112 NO. 6 / DECEMBER 2019
Fertility and Sterility® 66.
67.
68.
69.
Licht P, Losch A, Dittrich R, Neuwinger J, Siebzehnrubl E, Wildt L. Novel insights into human endometrial paracrinology and embryo-maternal communication by intrauterine microdialysis. Hum Reprod Update 1998;4: 532–8. Paiva P, Hannan NJ, Hincks C, Meehan KL, Pruysers E, Dimitriadis E, et al. Human chorionic gonadotrophin regulates FGF2 and other cytokines produced by human endometrial epithelial cells, providing a mechanism for enhancing endometrial receptivity. Hum Reprod 2011;26:1153–62. Craciunas L, Tsampras N, Raine-Fenning N, Coomarasamy A. Intrauterine administration of human chorionic gonadotropin (hCG) for subfertile women undergoing assisted reproduction. Cochrane Database Syst Rev 2018;10:CD011537. Sch€ unemann H, Bro_zek J, Guyatt G, Oxman A. GRADE handbook for grading quality of evidence and strength of recommendations. 1st ed. The GRADE Working Group; 2013.
VOL. 112 NO. 6 / DECEMBER 2019
70.
71. 72.
73.
74.
Stocking K, Wilkinson J, Lensen S, Brison D, Roberts S, Vail A. Are interventions in reproductive medicine assessed for plausible and clinically relevant effects? A review of power and precision in trials and meta-analyses. Hum Reprod 2019;34:659–65. Altman DG. The scandal of poor medical research. BMJ 1994;308:283–4. Thum MY, Abdalla HI, Bhaskaran S, Harden EL, Ford B, Sumar N, et al. The relationship of systemic TNF-alpha and IFN-gamma with IVF treatment outcome and peripheral blood NK cells. Am J Reprod Immunol 2007;57:210–7. Nakagawa K, Kwak-Kim J, Hisano M, Kasahara Y, Kuroda K, Sugiyama R, et al. Obstetric and perinatal outcome of the women with repeated implantation failures or recurrent pregnancy losses who received pre- and postconception tacrolimus treatment. Am J Reprod Immunol 2019;82:e13142. Yakin K, Oktem O, Urman B. Intrauterine administration of peripheral mononuclear cells in recurrent implantation failure: a systematic review and meta-analysis. Sci Rep 2019;9:1–7.
993
The probability of live birth from an in vitro fertilization (IVF) cycle is modest. Many additional treatments (add-ons) are available which promise to improve the success of IVF. This review summarizes the current evidence for common IVF add-ons which are suggested to improve endometrial receptivity. Systematic reviews of randomized controlled trials and individual trials were included. Five add-ons were included: immune therapies, endometrial scratching, endometrial receptivity array, uterine artery vasodilation, and human chorionic gonadotropin instillation. The results suggest there is no robust evidence that these add-ons are effective or safe. Many IVF addons are costly, consuming precious resources which may be better spent on evidence-based treatments or further IVF. Large randomized controlled trials and appropriate safety assessment should be mandatory before the introduction of IVF add-ons into routine practice. (Fertil SterilÒ 2019;112:987–93. Ó2019 by American Society for Reproductive Medicine.) Key Words: IVF add-on, treatment add-on, adjuvant, IVF adjunct Discuss: You can discuss this article with its authors and other readers at https://www.fertstertdialog.com/users/16110-fertilityand-sterility/posts/51850-28708
T
here is a plethora of adjunct or add-on interventions available to patients undergoing in vitro fertilization (IVF). Despite very few add-ons having any robust evidence of effectiveness or safety, their use is believed to be widespread (1). As the use of IVF add-ons is essentially unregulated, there are limited data available on worldwide prevalence; however, for example, it is estimated that 74% of women undergoing IVF in the U.K. used one or more add-ons in 2018 (2). Add-ons include many different interventions, including those suggested to increase the follicular response to ovarian stimulation, improve the culture conditions and quality of devel-
oping embryos, or prime the endometrium for impending implantation. Despite improvements in IVF technology over time, pregnancy rates have generally plateaued and high quality euploid embryos often fail to implant. Many IVF patients are being faced with a diagnosis of recurrent implantation failure after several repeated unsuccessful embryo transfers. These observations have led to an increased focus on the role of the endometrium in implantation (3, 4). As such, several add-ons have appeared on the market with the promise that they will improve the receptivity of the endometrium and increase the probability of live birth. The aim of this review is to summarize
Received July 31, 2019; revised September 28, 2019; accepted October 4, 2019. S.L. has nothing to disclose. N.S. has nothing to disclose. K.T.B. has nothing to disclose. A.G. has nothing to disclose. E.H.Y.N. has nothing to disclose. A.M. has nothing to disclose. Correspondence: Sarah Lensen, Ph.D., Department of Obstetrics and Gynaecology, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand (E-mail: [email protected]). Fertility and Sterility® Vol. 112, No. 6, December 2019 0015-0282/$36.00 Copyright ©2019 American Society for Reproductive Medicine, Published by Elsevier Inc. https://doi.org/10.1016/j.fertnstert.2019.10.011 VOL. 112 NO. 6 / DECEMBER 2019
the available evidence for common IVF add-ons proposed to enhance endometrial receptivity.
METHODS A long list of add-ons was compiled from those included in recent reviews (1, 5, 6). We then selected the add-ons suggested to improve endometrial receptivity specifically and merged similar add-ons into broader categories (for example, intralipid and corticosteroids are both considered under the add-on immune therapies). We then searched for Cochrane systematic reviews of randomized controlled trials (RCTs) assessing these add-ons. In general, Cochrane reviews have been demonstrated as higher quality and less biased than other systematic reviews (7, 8). If no Cochrane review was available, or the review was published before 2016 and may therefore be out of date, we expanded the search to recent systematic reviews of RCTs published in any journal (PubMed, last search June 2019). 987
VIEWS AND REVIEWS When no systematic review was available for a specific addon, we then searched for individual RCTs. We did not consider evidence from non-randomized trials (e.g. cohort, observational or case-control studies) as this evidence is prone to bias and does not provide robust evidence of safety or effectiveness. For each add-on, the current rating assigned by the UK Human Fertilisation and Embryology Authority (HFEA) was captured. Green is assigned where more than one good quality RCT has demonstrated the add-on to be effective and safe, amber is assigned in the case of conflicting evidence, and red when there is no evidence of effectiveness and safety (5). The HFEA has rated a total of 11 add-ons, and not all addons reviewed here have been rated at the time of this review. Costs of each add-on were obtained from the literature, internet searching and review of clinic websites. Institutional Review Board approval was not obtained as this is a literature review only.
RESULTS We identified five IVF add-ons suggested to improve endometrial receptivity: immune therapies, endometrial scratching, endometrial receptivity array (ERA), uterine artery vasodilation and human chorionic gonadotropin (hCG) instillation. For three add-ons, we reviewed a recent Cochrane review (endometrial scratching, vasodilators and hCG instillation), for another a recent non-Cochrane review (immune therapies), and for one add-on only an interim analysis of an RCT was available (ERA).
Immune therapies There is a common belief that the maternal immune system is damaging in early pregnancy and needs suppressing (9, 10). However, there is no high-quality evidence to support this notion, and the classical features of inflammation are not seen in decidua in early pregnancy (11). The immune cells allegedly responsible for implantation failure are specialized uterine natural killer cells (uNK). This unfortunate nomenclature gave rise to the idea that NK cells attack the fetus, causing implantation failure and pregnancy loss. NK cells circulating in peripheral blood are indeed cytotoxic to virally-infected or cancerous cells. However, uNK are phenotypically and functionally quite distinct from those in blood and only come into contact with placental trophoblast cells, not the fetus (12). Indeed, uNK cannot kill trophoblast in vitro (13). Despite these findings, there has been a dramatic rise in the use of assays and therapies devised to detect and remedy supposed immunological aberrations in the endometrium; such add-ons were used by 8% of UK couples accessing IVF in 2018 (2). Below we summarize four common immune therapies offered as addons to IVF, all of which, despite lack of any clear biological rationale, have been proposed to dampen the inflammatory and immune state of the endometrium and thereby increase the probability of implantation and pregnancy. Corticosteroids. Corticosteroids such as prednisolone are prescribed for the treatment of inflammatory conditions such as systemic lupus, erythematosus and rheumatoid arthritis. They are also commonly offered to IVF patients 988
near the time of embryo transfer. A Cochrane meta-analysis of 14 studies concluded that peri-implantation glucocorticoids provided no clear benefit in terms of live birth or pregnancy rate (14). These findings were corroborated more recently in additional systematic reviews (15, 16). Whilst the use of corticosteroids in patients with autoantibodies requires further investigation, there is sufficient evidence to recommend against the routine use of peri-implantation glucocorticoids for IVF (15). Furthermore, the safety of corticosteroids for the developing conceptus has not been studied robustly, and risks for the developing fetus are a concern. Observational studies reported possible causal associations between peri-implantation and first trimester corticosteroid exposure and the risk of oral cleft, major congenital anomalies, prematurity, and low birth weight (17). Indeed, the U.S. FDA has assigned a Category D rating to prednisolone due to evidence of adverse drug reactions for the fetus. Prednisolone is a cheap intervention, costing less than US$10 per IVF cycle (13, 18). Intravenous immunoglobulin. Intravenous immunoglobulin (IVIG) is an important therapy in diverse autoimmune and inflammatory disorders, as well as primary immunodeficiencies. Its effects on the systemic immune system are complex and how it might affect the uterine immune system is completely unknown (19). A recent systematic review included two small trials evaluating the application of IVIG during ovarian stimulation or near the time of embryo transfer, and reported no clinical benefit (15, 20, 21). IVIG requires administration in a supported medical environment as known adverse reactions include tachycardia, thromboembolic complications, and anaphylactic reactions (22). As such, the UK Department of Health does not recommend IVIG for IVF failure (23). Further, IVIG is an expensive therapy, costing US$2000 to $14,000 per IVF cycle (24-27). Granulocyte-Colony Stimulating Factor (G-CSF). Granulocyte-colony stimulating factor (G-CSF) is a cytokine secreted by immune cells such as macrophages, and recombinant human G-CSF is commonly used to treat hematological conditions such as neutropenia. G-CSF can be administered as an intrauterine instillation or subcutaneous injection near the time of embryo transfer, often in women with thin endometrium or recurrent implantation failure. The rationale for its use in IVF is not clear, and it comes at the cost of approximately US$100 to $599 (12, 28). Only a Cochrane protocol is available, and the review is currently in progress. Other recent systematic reviews identified 10 RCTs and reported possible benefit from G-CSF perfusion on the probability of clinical pregnancy (15, 29, 30). However, as many of the included trials lacked clear descriptions of randomization, were heterogeneous, and did not measure live birth, there is insufficient evidence to recommend for or against the use of G-CSF in practice (15). Intralipid. Intralipid is an emulsion of soy bean oil, egg phospholipids and glycerin, commonly administered as intravenous nutrition for patients not able to tolerate an oral diet. Intralipid is thought to also modulate immune function and has been observed to reduce the probability of spontaneous abortion in a mouse model (31). A systematic review VOL. 112 NO. 6 / DECEMBER 2019
Fertility and Sterility® identified only a single trial: a double-blind RCT which found that giving intralipid to women with ‘elevated NK cell levels’ did not improve chemical pregnancy rate (15, 32). This add-on costs approx. US$300 (33-35). While intravenous fat emulsion infusions are generally well tolerated, complications such as jaundice and hyperthermia have been reported (36). Additionally, there are examples of serious adverse events; immune therapies were considered to have contributed to the demise of a twin pregnancy at 23 weeks, following the development of severe systemic candidiasis (37). Reproductive immunology testing and treatment is currently rated red by the HFEA.
Endometrial scratching Endometrial scratching is a technique used to disrupt or injure the endometrium, commonly through the action of a pipelle biopsy, a routine gynecological procedure used for detecting possible intrauterine pathologies. The procedure is often performed in the luteal phase of the cycle prior to IVF (38). The resulting inflammation and activation of immune pathways is suggested to improve the receptivity of the endometrium to an implanting embryo, and although a number of other theories have also been put forward (39, 40), the biological plausibility of endometrial scratching has been questioned. It is difficult to conceive how any beneficial effect is retained when the entire functional layer of the endometrium is shed and replaced between the intervention and embryo implantation (41). This procedure has been subject to intense global interest and was the most common IVF add-on offered to fertility patients in the UK in 2016 (1). In 2018 endometrial scratching was used in 27% of IVF cycles in the UK (2). Over 80% of clinicians in a survey across New Zealand, Australia and the UK reported to recommend this procedure to their patients, at a cost of between USD $65 - $500 (38). The Cochrane review on this topic is currently being updated. Evidence from the previous update included 14 RCTs and reported possible benefit from endometrial scratching before IVF, with subgroup analysis suggesting the procedure may only help women with recurrent implantation failure (42). More recently, similar conclusions have been reported by a number of systematic reviews (43-45). Today, there have been over 30 trials published on this topic, and more are coming. Despite the wealth of clinical trial data, the information remains difficult to interpret: reported effects from endometrial scratching range from implausible benefit to significant harm (46, 47). The results of a large trial of more than 1,300 women was recently published which reports no benefit from endometrial scratching in women undergoing IVF, and subgroup analysis did not identify any subgroup of women who might benefit (48). While some researchers consequently call for abandoning scratching (49), others suggest certain (undefined) subgroups of women may still benefit from this procedure (50, 51). Endometrial biopsy has an established safety profile and adverse reactions are uncommon (e.g. vasovagal reaction, infection). However, the procedure is somewhat painful. In the available trials, patients reported pain scores between 3– 7 of 10, and the procedure was discontinued due to pain in VOL. 112 NO. 6 / DECEMBER 2019
a number of cases (46, 48, 52, 53). This add-on is currently rated amber by the HFEA.
Endometrial Receptivity Array The ERA is a novel diagnostic test based on microarray technology, created by a commercial enterprise. The test requires an appropriately timed endometrial biopsy to measure the endometrial expression of 248 genes (54). A sophisticated prediction model is then applied to categorize the endometrium as one of: receptive, pre-receptive, or proliferative. This categorization then enables women to undergo a personalized embryo transfer, where the exact timing of the transfer has been tailored to each woman’s personal window of implantation. The test has repeatedly demonstrated that women with recurrent implantation failure are more likely to suffer from a non-receptive endometrium, and approximately 25% of women with recurrent implantation failures are reported to have a displaced implantation window. Additionally, the test applied to the same women biopsied in multiple cycles will consistently produce the same result (54, 55). However, to date, only a single RCT has been completed, for which only interim and per-protocol analyses are available (56, 57). It is therefore not possible to confirm whether or not the ERA increases the probability of live birth. Despite lack of any robust evidence of benefit from RCTs, the ERA is widely used by IVF centers around the world; more than 55,000 ERA tests have been conducted in 60 countries (58). Evaluation of the ERA by external researchers is required to provide independent evidence evaluating this add-on, as has been suggested by others (59). However, at the cost of US$800 per test (28, 60), an adequately powered RCT recruiting >1,000 women would require $400,000 USD to cover the ERA cost alone. The ERA test requires an endometrial biopsy, necessitates a freeze-all cycle and repeated medicated cycles to enable ERA biopsy followed by personalized embryo transfer. As such, adverse events associated with endometrial biopsy, and the implications of delays and costs incurred by freeze-all and repeated cycles, should also be considered. This add-on is not currently rated by the HFEA.
Uterine artery vasodilation Vasodilators cause widening of blood vessel lumen and increased blood flow and are commonly used to treat conditions such as hypertension and erectile dysfunction. Thin endometrium, often defined as less than 7 or 8 mm, is associated with reduced probability of pregnancy during an IVF cycle (61, 62). Vasodilators such as sildenafil are therefore suggested to cause uterine vascular relaxation, increasing blood flow to the uterus and endometrium resulting in thickened endometrium and improved endometrial receptivity. If beneficial, such treatment would likely be costeffective as the cost of sildenafil is approximately US$20 per dose (18). A recent Cochrane review included 15 trials evaluating vasodilators in women undergoing IVF (63). The results report increased endometrial thickness to be associated with the use of vasodilators and suggest they 989
VIEWS AND REVIEWS may increase the chance of pregnancy in women undergoing IVF; however, the effect on live birth is unclear as only a small number of trials reported this outcome. Additionally, vasodilators were associated with increased adverse events such as headache and tachycardia. Indeed, sildenafil is associated with numerous drug reactions, including flushing, headache, abnormal vision, and insomnia (64). There are several other interventions proposed to increase endometrial thickness, such as aspirin and platelet-rich plasma. These add-ons are not specifically covered in this review, however recent guidelines suggest there is minimal evidence to support the use of these (65).This add-on is not currently rated by the HFEA.
these systematic reviews suffered from serious risk of bias, such as lack of blinding, no clear description of randomization and allocation concealment, premature termination of the study following (often unplanned) interim analysis, and lack of prospective trial registration. Additionally, the majority of trials contributing to the evidence-base summarized here recruited too few women to have enough statistical power to detect clinically relevant effect sizes, as is common in our field (70). For example, in the case of endometrial scratching, two thirds of trials reporting live birth recruited 200 women or fewer. A trial of 200 women would only be powered to detect an impressive and unrealistic improvement from IVF add-ons of 20 percentage points (e.g. from 25% to 45%, at 80% power and 5% significance level).
Intrauterine human chorionic gonadotropin Human chorionic gonadotropin is a hormone produced during pregnancy and is believed to regulate embryo implantation. hCG is often used during an IVF cycle to trigger final oocyte maturation, and costs approximately US$40 (18). Intrauterine infusion of hCG has been shown to upregulate cytokines known to be involved with implantation (66, 67). Injection or instillation of hCG into the uterine cavity prior to embryo transfer is therefore suggested to increase the probability of successful implantation by ensuring sufficient levels of hCG are present. A recent Cochrane review identified 17 RCTs (68). The authors observed high heterogeneity between trials and were therefore unable to pool the trials overall. However, in subgroup analyses it appears that among women undergoing cleavage stage embryo transfer, an hCG dose of R 500 IU increases the probability of clinical pregnancy and live birth. As this finding was only observed in a subgroup analysis, current evidence does not support the use of hCG injection in routine practice. This add-on is not currently rated by the HFEA.
Quality of the evidence Three of the five included add-ons (endometrial scratching, vasodilators, and hCG instillation) were evaluated by Cochrane reviews, which include a Grading of Recommendations, Assessment, Development and Evaluation (GRADE) assessment of the quality of evidence (69). In all cases, the quality of evidence varied between very low to moderate quality; in no case was the evidence found to be high quality. The Cochrane authors downgraded the evidence for risk of bias, imprecision, and inconsistency. For example, an Egyptian trial of endometrial scratching prior to IVF reported a live birth rate of 67% after endometrial scratching compared to 28% in the control group; producing an odds ratio 4.88 (95% confidence interval 3.22-7.40) in favor of endometrial scratching (46). Such a large effect size, and a live birth rate of 67%, is highly improbable. The heterogeneity of trial results observed by many of the included systematic reviews may arise in part due to differences in methodology between trials or the populations recruited. A more likely explanation may be poor quality of the included trials. Indeed, many of the studies included in 990
DISCUSSION This review summarizes the available evidence for common IVF add-ons proposed to improve endometrial receptivity and increase the probability of implantation and pregnancy. While there is weak evidence to suggest vasodilators and GCSF may offer increased probability of pregnancy in some women, heterogeneity, risk of bias and lack of data for live birth preclude recommendations for the routine use of any of these add-ons. Therefore, available evidence suggests the add-ons summarized here lack robust evidence, and should only be offered in experimental settings, namely randomized controlled trials. Unfortunately, these add-ons are already in routine use. The availability is not niche or restricted to a select few clinics; 74% of patients attending fertility clinics in the UK received one or more add-ons in 2018 (2). There appears to be a clear propensity for clinicians to provide costly IVF add-ons with no robust evidence base. Indeed, the ERA is used by IVF centers around the world; however, results are not yet available from a single (completed) RCT. The explanation for this is probably multifactorial. A likely contributor is the poor quality of the original primary research, much of which appears to demonstrate benefit from new IVF addons, which cannot be confirmed by subsequent trials. Many add-on treatments have been offered to patients as potentially promising therapies, followed by calls for robust evaluation by RCTs. Additionally, there is no clear incentive for companies to produce high-quality RCT evidence which may risk disproving their claims. Academics and researchers without appropriate expertise or experience are free to conduct small, biased, RCTs, and to publish these in peer reviewed journals, often despite lack of adequate trial registration. We repeat sentiments published 25 years ago ‘‘much poor research arises because researchers feel compelled for career reasons to carry out research that they are ill equipped to perform, and nobody stops them’’ (71). There appears to be little consideration for biological plausibility in the innovation of new add-ons, which often appear to be based on a misunderstanding of the science of implantation. Intralipid started out as a placebo: due to its similar appearance, intralipid was used as the control treatment in the evaluation of immunotherapy using syncytiotrophoblast membranes (cited in [32]). There is no clear rationale VOL. 112 NO. 6 / DECEMBER 2019
Fertility and Sterility® to support the transition of intralipid from an inert placebo to a common IVF add-on. The development of add-ons devised to improve endometrial receptivity should be based on a thorough understanding of the molecular and cellular events occurring at implantation. Increased collaboration between clinicians, reproductive biologists and immunologists may lead to better progress. Clinicians are also driven by a genuine desire to increase pregnancy rates, and the ability to offer couples something ‘extra’ when faced with multiple failed attempts. In the case of poor prognosis or previous IVF failure, clinicians may view any additional intervention as possibly beneficial to the patient, who is otherwise very unlikely to conceive. However, in an increasingly commercialized sector, motivations also risk being driven by marketing and financial gain, to offer something your competitors do not. Such conflicts of interest are especially dangerous in the context of a vulnerable population who may do (and pay) whatever it takes. Clinicians recommending add-ons should also consider the risk of harm. However, one cannot easily make an informed assessment of benefit vs. harm when the evidence for benefit is poor, and that for harm is even worse. Most of the trials investigating these interventions fail to report adverse events, and rare but serious harms may be difficult to detect. For example, there is special concern of congenital anomalies and prematurity from glucocorticoid exposure in pregnancy (17); any actual increased risk in the context of peri-implantation exposure could only be assessed through large cohort or case-control studies (which have not been performed). Other harms may seem less serious but should not be overlooked, including known adverse side-effects, costs to patients, and the potential psychological harms of offering false hope. There are several limitations to this review which should be noted. Firstly, this was not a systematic literature review and did not rely on a comprehensive search of the primary literature; therefore, relevant publications may have been missed. We only included add-ons deemed to be in common use, and those discussed here are not exhaustive; for example other available immune therapies include TNF-a blockers (72), tacrolimus (73), and intrauterine injection of peripheral blood mononuclear cells (74). Further, much of the evidence regarding cost comes from certain countries including the UK, U.S. and Australia, and prices have been converted to the USD equivalent. These figures only provide a guide as information about cost was not collected systematically and may vary substantially in different settings.
CONCLUSION This review summarizes the current evidence for common IVF add-ons which are suggested to improve endometrial receptivity: immune therapies, endometrial scratching, endometrial receptivity array, uterine artery vasodilation and human chorionic gonadotropin instillation. The results suggest there is no robust evidence that these add-ons are effective or safe. Many IVF add-ons are costly, consuming precious resources which may be better spent on evidenceVOL. 112 NO. 6 / DECEMBER 2019
based treatments or further IVF. Large RCTs and appropriate safety assessment should be mandatory before the introduction of IVF add-ons into routine practice.
REFERENCES 1.
2.
3.
4.
5.
6. 7.
8.
9.
10.
11.
12. 13.
14.
15.
16.
17.
18. 19. 20.
21.
Spencer EA, Mahtani KR, Goldacre B, Heneghan C. Claims for fertility interventions: a systematic assessment of statements on UK fertility centre websites. BMJ Open 2016:1–6. Human Fertilisation and Embryology Authority. The National Fertility Patient Survey; 2018. Available at: https://www.hfea.gov.uk/media/2702/pilotnational-fertility-patient-survey-2018.pdf. Emerging role for dysregulated decidualization in the genesis of preeclampsia. In: Conrad KP, Rabaglino MB, Uiterweer Post, editors. Placenta 2017;60: 119–29. Garrido-Gomez T, Dominguez F, Quinonero A, Diaz-Gimeno P, Kapidzic M, Gormley M, et al. Defective decidualization during and after severe preeclampsia reveals a possible maternal contribution to the etiology. Proc Natl Acad Sci U S A 2017;114:E8468–77. Human Fertilisation and Embryology Authority. Treatment add-ons. 2018. Available at: https://www.hfea.gov.uk/treatments/explore-all-treatments/ treatment-add-ons/. Datta AK, Campbell S, Deval B, Nargund G. Add-ons in IVF programme hype or hope? Facts Views Vis Obgyn 2015;7:241–50. Goldkuhle M, Narayan VM, Weigl A, Dahm P, Skoetz N. A systematic assessment of Cochrane reviews and systematic reviews published in high-impact medical journals related to cancer. BMJ Open 2018;8:e020869. Jørgensen AW, Hilden J, Gøtzsche PC. Cochrane reviews compared with industry supported meta-analyses and other meta-analyses of the same drugs: systematic review. BMJ 2006;333:782. Yamada H, Morikawa M, Kato EH, Shimada S, Kobashi G, Minakami H. Preconceptional natural killer cell activity and percentage as predictors of biochemical pregnancy and spontaneous abortion with normal chromosome karyotype. Am J Reprod Immunol 2003;50:351–4. Sacks G, Yang Y, Gowen E, Smith S, Fay L, Chapman M. Detailed analysis of peripheral blood natural killer cells in women with repeated IVF failure. Am J Reprod Immunol 2012;67:434–42. Vento-Tormo R, Efremova M, Botting RA, Turco MY, Vento-Tormo M, Meyer KB, et al. Single-cell reconstruction of the early maternal-fetal interface in humans. Nature 2018;563:347–53. Moffett A, Shreeve N. First do no harm: uterine natural killer (NK) cells in assisted reproduction. Hum Reprod 2015;30:1519–25. King A, Birkby C, Loke YW. Early human decidual cells exhibit NK activity against the K562 cell line but not against first trimester trophoblast. Cell Immunol 1989;118:337–44. Boomsma CM, Keay SD, Macklon NS. Peri-implantation glucocorticoid administration for assisted reproductive technology cycles. Cochrane Database of Systematic Reviews 2012;6:005996. Practice Committee of the American Society for Reproductive Medicine. The role of immunotherapy in in vitro fertilization: a guideline. Fertil Steril 2018; 110:387–400. Achilli C, Duran-Retamal M, Saab W, Serhal P, Seshadri S. The role of immunotherapy in in vitro fertilization and recurrent pregnancy loss: a systematic review and meta-analysis. Fertil Steril 2018;110:1089–100. Robertson SA, Jin M, Yu D, Moldenhauer LM, Davies MJ, Hull ML, et al. Corticosteroid therapy in assisted reproduction - immune suppression is a faulty premise. Hum Reprod.2016;31:2164-2173. Herts and Essex Fertility Centre. Price list 2019. Available at: https:// hertsandessexfertility.com/price-list/. Accessed August 1, 2019. Galeotti C, Kaveri SV, Bayry J. IVIG-mediated effector functions in autoimmune and inflammatory diseases. Int Immunol 2017;29:491–8. Stephenson MD, Fluker MR. Treatment of repeated unexplained in vitro fertilization failure with intravenous immunoglobulin: a randomized, placebo-controlled Canadian trial. Fertil Steril 2000;74:1108–13. De Placido G, Zullo F, Mollo A, Cappiello F, Nazzaro A, Colacurci N, et al. Intravenous immunoglobulin (IVIG) in the prevention of implantation failures. Ann N Y Acad Sci 1994;734:232–4. 991
VIEWS AND REVIEWS 22. 23.
24. 25. 26.
27. 28. 29.
30. 31. 32.
33.
34. 35. 36.
37.
38. 39.
40.
41.
42.
43.
44.
45.
992
Katz U, Achiron A, Sherer Y, Shoenfeld Y. Safety of intravenous immunoglobulin (IVIG) therapy. Autoimmun Rev 2007;6:257–9. Department of Health and Social Care. Clinical guidelines for immunoglobulin use (second edition update); 2011. Available at: https://assets. publishing.service.gov.uk/government/uploads/system/uploads/attachment_ data/file/216671/dh_131107.pdf. Intravenous immunoglobulin (IVIG) and recurrent spontaneous pregnancy loss. Fertil Steril 2006;86(5 Suppl 1):S226-7. CNY Fertility. IVIG therapy. 2019. Available at: https://www.cnyfertility.com/ ivig-therapy/. Accessed July 1, 2019. Braverman IVF & Reproductive Immunology. IVIG treatment for miscarriages. 2019. Available at: https://www.preventmiscarriage.com/intravenousimmunoglobulin-ivig-.html. Accessed July 1, 2019. LA IVF. Intravenous imunoglobulin (IVIG) for IVF. 2019. Available at: https:// laivfclinic.com/intravenousimmunoglobulin/. Accessed July 1, 2019. Fertility North. Fees. 2019. Available at: http://www.fertilitynorth.com.au/ fees/. Accessed July 1, 2019. Zhang L, Xu WH, Fu XH, Huang QX, Guo XY, Zhang L, et al. Therapeutic role of granulocyte colony-stimulating factor (G-CSF) for infertile women under in vitro fertilization and embryo transfer (IVF-ET) treatment: a meta-analysis. Arch Gynecol Obstet 2018;298:861–71. Li J, Mo S, Chen Y. The effect of G-CSF on infertile women undergoing IVF treatment: a meta-analysis. Syst Biol Reprod Med 2017;63:239–47. Clark DA. Intralipid as treatment for recurrent unexplained abortion? Am J Reprod Immunol 1994;32:290–3. Dakhly DM, Bayoumi YA, Sharkawy M, Gad Allah SH, Hassan MA, Gouda HM, et al. Intralipid supplementation in women with recurrent spontaneous abortion and elevated levels of natural killer cells. Int J Gynaecol Obstet 2016;135:324–7. Heneghan C, Spencer EA, Bobrovitz N, Collins DRJ, Nunan D, Pl€ uddemann A, et al. Lack of evidence for interventions offered in UK fertility centres. BMJ 2016;355. The Fertility & Gynaecology Academy. Fees. 2019. Available at: https:// www.fertility-academy.co.uk/fees/. Accessed July 1, 2019. The Fertility & Gynaecology Academy. Our fees. 2019. Available at: https:// argc.co.uk/our-fees/. Accessed July 1, 2019. Hansen LM, Hardie BS, Hidalgo J. Fat emulsion for intravenous administration: clinical experience with intralipid 10%. Ann Surg 1976;184: 80–8. Akhanoba F, MacDougall J, Mathur R, Hassan W. Severe systemic candidiasis following immunomodulation therapy in in vitro fertilisation-embryo transfer (IVF-ET). BMJ Case Rep 2014;2014. https://doi.org/10.1136/ bcr,2013-203202. Lensen S, Sadler L, Farquhar C. Endometrial scratching for subfertility: everyone's doing it. Hum Reprod 2016;31:1241–4. Zhou L, Li R, Wang R, Huang HX, Zhong K. Local injury to the endometrium in controlled ovarian hyperstimulation cycles improves implantation rates. Fertil Steril 2008;89:1166–76. Gibreel A, El-Adawi N, Elgindy E, Al-Inany H, Allakany N, Tournaye H. Endometrial scratching for women with previous IVF failure undergoing IVF treatment. Gynecol Endocrinol 2015;31:1–4. n C, Bellver J. Scratching beneath 'the Scratching Case': systematic reSimo views and meta-analyses, the back door for evidence-based medicine. Hum Reprod 2014;29:1618–21. Nastri CO, Lensen SF, Gibreel A, Raine-Fenning N, Ferriani RA, Bhattacharya S, et al. Endometrial injury in women undergoing assisted reproductive techniques. Cochrane Database Syst Rev 2015;3:CD009517. Gui J, Xu W, Yang J, Feng L, Jia J. Impact of local endometrial injury on in vitro fertilization/intracytoplasmic sperm injection outcomes: A systematic review and meta-analysis. J Obstet Gynaecol Res 2019;45:57–68. van Hoogenhuijze NE, Kasius JC, Broekmans FJM, Bosteels J, Torrance HL. Endometrial scratching prior to IVF; does it help and for whom? A systematic review and meta-analysis. Hum Reprod Open 2019;2019:1–18. Vitagliano A, Di Spiezio Sardo A, Saccone G, Valenti G, Sapia F, Kamath MS, et al. Endometrial scratch injury for women with one or more previous failed embryo transfers: a systematic review and meta-analysis of randomized controlled trials. Fertil Steril 2018;110:687–702.e2.
46.
47.
48.
49. 50.
51. 52.
53.
54.
55.
56.
57.
58. 59.
60.
61.
62.
63.
64.
65.
Mahran A, Ibrahim M, Bahaa H. The effect of endometrial injury on first cycle IVF/ICSI outcome: A randomized controlled trial. Int J Reprod Biomed 2016; 14:193–8. Karimzade MA, Oskouian H, Ahmadi S, Oskouian L. Local injury to the endometrium on the day of oocyte retrieval has a negative impact on implantation in assisted reproductive cycles: A randomized controlled trial. Arch Gynecol Obstet 2010;281:499–503. Lensen S, Osavlyuk D, Armstrong S, Stadelmann C, Hennes A, Napier E, et al. A randomized trial of endometrial scratching before in vitro fertilization. N Engl J Med 2019;380:325–34. Mol BW, Barnhart KT. Scratching the endometrium in in vitro fertilization time to stop. N Engl J Med 2019;380:391–2. Lensen S, Venetis C, Ng EHY, Young SL, Vitagliano A, Macklon NS, et al. Should we stop offering endometrial scratching prior to in vitro fertilization? Fertil Steril 2019;111:1094–101. Macklon NS, Ahuja KK, Fauser B. Building an evidence base for IVF 'addons'. Reprod Biomed Online 2019;38:853–6. Polanski LT, Baumgarten MN, Richardson A, Sewell K, Brosens JJ, Quenby S, et al. Endometrial biopsy prior to assisted reproductive techniques (ART) does not improve treatment outcome in unselected patients. Hum Reprod Annual Meeting of ESHRE 2015 (O-027). Frantz S, Parinaud J, Kret M, Rocher-Escriva G, Papaxanthos-Roche A, Creux H, et al. Decrease in pregnancy rate after endometrial scratch in women undergoing a first or second in vitro fertilization. A multicenter randomized controlled trial. Hum Reprod 2019;34:92–9. Ruiz-Alonso M, Blesa D, Diaz-Gimeno P, Gomez E, Fernandez-Sanchez M, Carranza F, et al. The endometrial receptivity array for diagnosis and personalized embryo transfer as a treatment for patients with repeated implantation failure. Fertil Steril 2013;100:818–24. Díaz-Gimeno P, Ruiz-Alonso M, Blesa D, Bosch N, Martínez-Conejero JA, Alama P, et al. The accuracy and reproducibility of the endometrial receptivity array is superior to histology as a diagnostic method for endometrial receptivity. Fertil Steril 2013;99:508–17. Simon C, Vladimirov IK, Castillon Cortes G, Ortega I, Cabanillas S, Vidal C, et al. Prospective, randomized study of the endometrial receptivity analysis (ERA) test in the infertility work-up to guide personalized embryo transfer versus fresh transfer or deferred embryo transfer. Fertil Steril 2016;106: e46–7. Simon C, Gomez C, Cabanillas S, Vladimirov IK, Castillon G, Giles J, et al. In vitro fertilization with personalized blastocyst transfer versus frozen or fresh blastocyst transfer: a multicenter, randomized clinical trial. Fertil Steril 2019;112:e56. ERA® Endometrial Receptivity Analysis. 2019. Available at: https://www. igenomix.com/our-services/era/. Accessed November 19, 2019. Cho K, Tan S, Buckett W, Dahan MH. Intra-patient variability in the endometrial receptivity assay (ERA) test. J Assist Reprod Genet 2018;35: 929–30. What to know about endometrial receptivity analysis. 2019. Available at: https://fertility.igenomix.com/blog/what-to-know-about-endometrial-rece ptivity-analysis/. Accessed July 1, 2019. Check JH. The importance of sonographic endometrial parameters in influencing success following embryo transfer in the modern era and therapeutic options–part 1: the importance of late proliferative phase endometrial thickness. Clin Exp Obstet Gynecol 2011;38:197–200. Gonen Y, Casper RF. Prediction of implantation by the sonographic appearance of the endometrium during controlled ovarian stimulation for in vitro fertilization (IVF). J In Vitro Fert Embryo Transf 1990;7:146–52. Gutarra-Vilchez RB, Bonfill Cosp X, Glujovsky D, Viteri-García A, RunzerColmenares FM, Martinez-Zapata MJ. Vasodilators for women undergoing fertility treatment. Cochrane Database of Systematic Reviews 2018. https://doi.org/10.1002/14651858.CD010001.pub3. Moreira SG Jr, Brannigan RE, Spitz A, Orejuela FJ, Lipshultz LI, Kim ED. Sideeffect profile of sildenafil citrate (Viagra) in clinical practice. Urology 2000; 56:474–6. Liu KE, Hartman M, Hartman A. Management of thin endometrium in assisted reproduction: a clinical practice guideline from the Canadian Fertility and Andrology Society. Reprod BioMed Online 2019;39:49–62.
VOL. 112 NO. 6 / DECEMBER 2019
Fertility and Sterility® 66.
67.
68.
69.
Licht P, Losch A, Dittrich R, Neuwinger J, Siebzehnrubl E, Wildt L. Novel insights into human endometrial paracrinology and embryo-maternal communication by intrauterine microdialysis. Hum Reprod Update 1998;4: 532–8. Paiva P, Hannan NJ, Hincks C, Meehan KL, Pruysers E, Dimitriadis E, et al. Human chorionic gonadotrophin regulates FGF2 and other cytokines produced by human endometrial epithelial cells, providing a mechanism for enhancing endometrial receptivity. Hum Reprod 2011;26:1153–62. Craciunas L, Tsampras N, Raine-Fenning N, Coomarasamy A. Intrauterine administration of human chorionic gonadotropin (hCG) for subfertile women undergoing assisted reproduction. Cochrane Database Syst Rev 2018;10:CD011537. Sch€ unemann H, Bro_zek J, Guyatt G, Oxman A. GRADE handbook for grading quality of evidence and strength of recommendations. 1st ed. The GRADE Working Group; 2013.
VOL. 112 NO. 6 / DECEMBER 2019
70.
71. 72.
73.
74.
Stocking K, Wilkinson J, Lensen S, Brison D, Roberts S, Vail A. Are interventions in reproductive medicine assessed for plausible and clinically relevant effects? A review of power and precision in trials and meta-analyses. Hum Reprod 2019;34:659–65. Altman DG. The scandal of poor medical research. BMJ 1994;308:283–4. Thum MY, Abdalla HI, Bhaskaran S, Harden EL, Ford B, Sumar N, et al. The relationship of systemic TNF-alpha and IFN-gamma with IVF treatment outcome and peripheral blood NK cells. Am J Reprod Immunol 2007;57:210–7. Nakagawa K, Kwak-Kim J, Hisano M, Kasahara Y, Kuroda K, Sugiyama R, et al. Obstetric and perinatal outcome of the women with repeated implantation failures or recurrent pregnancy losses who received pre- and postconception tacrolimus treatment. Am J Reprod Immunol 2019;82:e13142. Yakin K, Oktem O, Urman B. Intrauterine administration of peripheral mononuclear cells in recurrent implantation failure: a systematic review and meta-analysis. Sci Rep 2019;9:1–7.
993