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Transfer and uterine factors are the major recipient-related determinants of success with donor eggs
FERTILITY AND STERILITY威 VOL. 82, NO. 4, OCTOBER 2004 Copyright ©2004 American Society for Reproductive Medicine Published by Elsevier Inc. Printed on acid-free paper in U.S.A.
Transfer and uterine factors are the major recipient-related determinants of success with donor eggs Ulrike Zenke, M.D., and Ryszard J. Chetkowski, M.D. Alta Bates In Vitro Fertilization Program, Berkeley, California
Objective: To define the recipient-related determinants of outcome with donor eggs. Design: Case-control study. Setting: Community hospital-based assisted reproductive technology (ART) program. Patient(s): One hundred thirty-four embryo transfers (ETs) in which two recipients were matched to one donor. Intervention(s): Controlled ovarian hyperstimulation (COH) and ovum retrieval in donors; IVF and ET to recipients. Main Outcome Measure(s): Recipients’ age, body mass index (BMI), medical conditions, endometriosis, gravidity, uterine pathology, endometrial thickness, egg number, total motile sperm count, intracytoplasmic sperm injection (ICSI), zygote number, fertilization rate, embryos per ET, embryos frozen, embryo quality, difficulty with transfer, and ongoing pregnancies per ET. Result(s): Forty-one recipient pairs had discordant outcomes. Pregnant patients had a lower frequency (9.7% vs. 31.7%, P⫽.04) and lesser severity of uterine pathology. Endometrium ⬍8 mm was found solely in failed cycles. Pregnant women had fewer moderate or difficult ETs (9.7% vs. 31.7%, P⫽.04) and more good embryos (1.8 vs. 1.3, P⫽.03) than the nonpregnant group. Conclusion(s): Analysis of recipient pairs with discordant outcomes identifies the recipient-related predictors of success by keeping oocyte quality and the laboratory component constant. Uterine pathology, thin endometrium, transfer difficulty, and number of high-grade embryos are the principal recipient-related determinants of outcome with donor eggs. (Fertil Steril威 2004;82:850 – 6. ©2004 by American Society for Reproductive Medicine.) Key words: Egg donation, uterine factor infertility, ET, uterine receptivity, embryo implantation, endometrial thickness, donor egg recipients, aging of the uterus, donor egg outcome, uterine senescence
Received December 23, 2003; revised and accepted March 24, 2004. Presented in part at the 51st Annual Meeting of the Pacific Coast Reproductive Society, Rancho Mirage, California, April 25–27, 2003. Reprint requests: Ryszard J. Chetkowski, M.D., Alta Bates Medical Center, 2999 Regent Street, Suite 101-A, Berkeley, California 94704 (FAX: 510-649-8700; E-mail: [email protected]). 0015-0282/04/$30.00 doi:10.1016/j.fertnstert.2004. 03.057
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Pregnancy initiation with donated eggs is a common treatment for a wide spectrum of infertility conditions including advanced female age, premature ovarian failure (POF), repetitive failure of IVF, and genetic disorders. The key feature of donor egg treatment is that it permits simultaneous yet separate optimization of oocyte quantity and quality in the fertile donor, and of endometrial receptivity in the infertile recipient. For this reason it has consistently produced the highest live birth rate of all the assisted reproductive technologies (ART). Nonetheless, only 43.4% of the fresh donor egg transfers reported in the year 2000 resulted in a live birth (1). The causes of failure have proven difficult to define because of the multiple sources of heterogeneity inherent in this com-
plex process, such as egg donors, stimulation regimens, laboratory conditions, transfer techniques, and recipient characteristics (2). The recipient-related variables previously reported to affect donor egg outcome include chemotherapy and radiotherapy (3, 4), Asherman’s syndrome (5), thin endometrium (6, 7), and hydrosalpinx (5, 8). Embryo quality clearly plays a preeminent role in all assisted reproduction, including donor eggs (7), but it is also the one variable most difficult to control. Albeit egg donation may involve a more homogeneous population of ova and embryos than traditional IVF (4), marked differences in the egg factor exist even among young and fertile donors (2). When embryo implantation fails, it is often unclear
whether the failure is attributable to the egg factor or to a recipient-related variable. The current study seeks to delineate the major recipientrelated predictors of success by examining paired ovum recipients sharing ova from a single donor. Thus, the egg factor, which is determined by the donor’s intrinsic fecundity and the vagaries of a particular treatment cycle, as well as the laboratory component remain constant for each recipient pair. Focusing on recipient pairs with discordant outcomes assures that the shared ova are of sufficient quality to establish an ongoing pregnancy in one of the recipients. Therefore, the major recipient characteristics associated with failure to conceive become apparent. Obviously, factors amenable to clinical intervention are of special interest.
MATERIALS AND METHODS Between January 1992 and December 2001, 116 infertile recipients underwent a total of 134 cycles in which two women were matched to one young, healthy, fertile, anonymous, compensated egg donor at the Alta Bates In Vitro Fertilization Program. Of the 116 recipients, 12 women underwent two cycles and 3 women had three fresh transfers each. Our donor screening and donor-recipient matching strategies have been previously described (9). A typical egg donor is a married 28-year-old woman with an average of 1.5 children who undergoes 2.5 retrievals over a period of 11 months. Donors who previously produced ⱖ14 oocytes were eligible for matching to two recipients. The study adhered to the guidelines of the Declaration of Helsinki. Because no clinical interventions were performed specifically for the purpose of this study and no subjects were contacted for interview, a separate application was not made to the Committee for the Protection of Human Subjects at the Alta Bates Medical Center. All the donors and recipients consented in writing to reporting of clinical results without identifying information. The initial chart review was conducted without the reviewer’s (U.Z.) knowledge of the match status of the infertile women and their donors. The 134 treatment cycles were classified according to whether or not an ongoing pregnancy, defined as at least one intrauterine fetus with heart motion documented by ultrasound at 11–12 weeks, was established. All donors underwent controlled ovarian hyperstimulation (COH) with leuprolide acetate (LA) and hMG with standard monitoring by serum E2 and ultrasound. Oocytes were retrieved transvaginally with ultrasound-guidance 35–36 hours after the hCG trigger. The oocytes were equally and randomly assigned to the paired recipients on the day of retrieval. When an odd number of eggs were obtained, the recipient with longer tenure in the program received the extra egg. All prospective recipients had a hysterosalpingogram within 2 years and a vaginal ultrasound within 2– 4 months FERTILITY & STERILITY威
of the treatment cycle. Saline sonohysterography and diagnostic hysteroscopy were used in select cases. When present, submucous fibroids and hydrosalpinges were removed by operative hysteroscopy and laparoscopy, respectively. Trial ET and semen analysis were done in all cases. Recipients with menses underwent pituitary downregulation with LA beginning either in the midluteal phase of the previous cycle as confirmed by serum P4 or 5 days before stopping oral contraceptives (OC). After onset of bleeding, the endometrium was prepared with step-up estrogen (E) in the form of either E2 valerate given IM twice per week, transdermal E2 patches, or oral micronized E2 for 14 –28 days. Each recipient pair followed the same initial E replacement protocol. A vaginal ultrasound was done about 1 week before the anticipated ovum retrieval at which time the dose of E2 was increased if the uterine lining was ⬍9 mm. Endometrium was measured in the sagittal plane in the thickest fundal portion from one endometrial–myometrial junction to the other. Progesterone-in-oil was given IM as a single daily injection of 75 mg starting the evening before ovum retrieval; since 1993, 400 mg of P4 was added vaginally at bedtime (10). Intracytoplasmic sperm injection (ICSI) was performed for cases with male factor infertility since 1994. The embryos were graded according to blastomere number, symmetry, and the percentage of fragmentation. Embryos with ⬎3 cells at 2 days and ⱖ7 cells at 3 days after retrieval with good blastomere morphology and ⬍10% fragmentation were considered highgrade embryos. Blastocysts were considered high-grade when exhibiting a well-developed inner cell mass. All embryos were transferred transcervically in the lithotomy position by the senior author (R.J.C.). From 1992 to 1995 ET was performed with the Tomcat catheter without ultrasound guidance 2 days after retrieval. Since 1996 embryos have been replaced with the Wallace catheter with ultrasound guidance either 3 or 5 days after retrieval. Each recipient pair had embryos transferred at the same stage of development. Transfers were rated as easy, moderate, or difficult in addition to recording specific information about the use of instruments, bleeding, and other technical aspects. Easy transfers required no instrumentation. Moderate transfers included the use of a malleable Wallace stylet, mild cervical traction, as well as double transfers necessitated by retained embryos. Difficult transfers involved the use of strong countertraction, probing, or dilation of the cervical canal. Serum hCG and P4 were done 12–13 days after retrieval. The dose of P-in-oil was adjusted to maintain serum P4 ⱖ25 ng/mL at nadir. Hormonal supplementation was stopped with evidence of endogenous placental secretion, typically at 11–12 weeks. Vaginal ultrasounds were performed at 5– 6, 8 –9, and 11–12 weeks to evaluate the progress of pregnancy. At the end of the first trimester patients with ongoing pregnancies were referred for obstetrical care. 851
TABLE 1 Comparison of variables between the pregnant and nonpregnant subjects in the group with discordant outcomes. Variable Age (y)a Normal BMI (19–25 kg/m2) Prior pregnanciesa Preexisting medical conditions Endometriosis Oocyte numbera Total motile sperm (million)a ICSI Fertilization rate Number of 2PN zygotesa Embryos/transfera Frozen embryosa High grade embryosa a
Pregnant (n ⫽ 41)
Nonpregnant (n ⫽ 41)
P value
43.4 (30–51) 76% 2.2 (0–3) 12.2% 7.3% 10.6 (5–25) 174 (4.4–903) 12.2% 72.6% 7.7 (3–19) 3.78 (2–6) 1.7 (0–6) 1.8 (0–11)
43.6 (39–50) 71% 1.1 (0–3) 22.0% 19.5% 10.5 (4–24) 169 (0.1–609) 14.5% 72.9% 7.6 (2–17) 3.95 (2–6) 2.0 (0–10) 1.3 (0–11)
.62 .64 .003 .24 .10 .91 .96 .74 .84 .91 .24 .63 .03
Values are means (ranges).
Zenke. Uterine factors impair donor egg success. Fertil Steril 2004.
Statistical Analysis
Statistical tests included 2 and paired t test as appropriate, with statistical significance defined as P⬍.05.
RESULTS In the entire study population of 116 infertile women who underwent 134 fresh donor egg cycles, 61 ongoing intrauterine pregnancies were established, which corresponds to 45.5% per transfer and 52.6% per patient. Fertilization and transfer were achieved in all cases and spare embryos were frozen in 46.2% of cycles. Of the 61 ongoing pregnancies, 58 (95.1%) resulted in the birth of at least one live infant. One patient had an unexplained fetal demise in midtrimester after having a viable fetus at 11 weeks. Two patients terminated their pregnancies in midtrimester: one due to multiple fetal malformations and one due to psychological problems. Of 67 recipients pairs, 41 (61.2%) had discordant outcomes where only one recipient achieved an ongoing pregnancy. Twenty-six recipient pairs (38.8%) had concordant outcomes: in 10 pairs (14.9%) both women achieved an ongoing pregnancy and in 16 pairs (23.9%), neither woman conceived. The distribution of discordant and concordant outcomes was not different from that expected on theoretical grounds given the overall pregnancy rate (PR) per transfer. The 41 pairs of recipients with discordant outcomes underwent detailed evaluation. Table 1 lists the examined variables. The mean age did not differ and the percentage of cycles in women ⬍40 and ⬎47 years was similar in the pregnant and nonpregnant groups. No significant differences were found with regard to body mass index (BMI), preexisting medical conditions, or endometriosis. However, the mean number of prior pregnancies was higher in the pregnant than the nonpregnant group (2.2 vs. 1.1, P⫽.003). 852
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Whereas the oocyte number, total motile sperm count, the use of ICSI, fertilization rate, number of 2PN zygotes, number of embryos per transfer, and number of embryos frozen were comparable, pregnant recipients had more high-grade embryos than their nonpregnant counterparts (1.8 vs. 1.3; P⫽.03). Figure 1 shows the frequency of the three major factors: uterine pathology, thin endometrium, and ET difficulty in the two groups. Uterine pathology was both less common and less severe in the pregnant (9.8%) than in the nonpregnant group (31.7%, P⫽.04). Among pregnant women, fibroids were the only uterine abnormality: three patients had prior myomectomies without evidence of recurrence, whereas one patient had a lower uterine segment intramural fibroid. In the
FIGURE 1 Uterine pathology, thin endometrium, and transfer difficulty in the pregnant and nonpregnant subjects in the group with discordant outcomes (*P⫽.04; **P⫽.01).
Zenke. Uterine factors impair donor egg success. Fertil Steril 2004.
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nonpregnant group, six women had a history of fibroids: four patients had prior myomectomies but one of them had recurrence with a 12-week size uterus. Two patients had intramural fibroids without encroachment on the uterine cavity.
FIGURE 2 The percentage of cycles with one, two, or three major factors (uterine pathology, thin endometrium, and transfer difficulty) in the pregnant and nonpregnant subjects in the group with discordant outcomes (*P⫽.001).
In the nonpregnant group, seven cycles were completed in women with severe uterine abnormalities such as Asherman’s syndrome, T-shaped cavity resulting from antenatal exposure to diethylstilbesterol (DES), corrected uterine septum combined with adenomyosis, and hyperechoic foci on ultrasound due to dystrophic calcifications from a prior midtrimester termination. None of the patients with severe uterine pathology ever achieved implantation while in the practice despite undergoing nine fresh and four frozen ETs with replacement of a total of 48 embryos. In her final attempt, one woman shared donor eggs with her fertile twin sister who, acting as a gestational carrier, delivered fraternal twins from transfer of just two embryos. The average endometrial thickness of 10.8 mm in the pregnant group was not statistically different from that in the nonpregnant group (9.8 mm). However, none of the pregnant patients had endometrium ⬍8 mm, whereas lining ⬍8 mm was found in six failed cycles (14.5%, P⫽.01). In five cycles, thin endometrium was associated with one of the severe uterine pathologies. Only the patient with isolated lining ⬍8 mm had previously achieved a live birth in an IVF cycle during which her endometrium measured 11 mm. A lower frequency and lesser degree of difficulty with ET was found in the pregnant compared to the nonpregnant group (9.7% vs. 31.7%, P⫽.04). In the former, four transfers were rated as moderate but none was difficult. In comparison, there were seven moderate and six difficult ETs in the nonpregnant group. Women with structural uterine abnormalities accounted for three moderate but none of the difficult ETs. Of the six women with difficult transfers in the index cycles, four underwent an additional eight ETs outside the study. Five (62.5%) of those eight transfers were also difficult. The sole patient to achieve a live birth had an easy transfer in the conception cycle. Figure 2 shows the combinations of the three major factors in the pregnant and nonpregnant groups. In the pregnant group, 9 of 41 cycles (22.0%) were associated with one factor but none had more than one factor. In contrast, in the nonpregnant group, 18 cycles (43.9%) had one factor, 5 cycles (12.2%) had two factors, and 1 cycle (2.4%) had all three factors. Thus, at least one of the three factors was implicated in 24 of 41 failed cycles (58.5%) compared to only 22.0% of the pregnancy cycles (P⫽.001).
DISCUSSION Because the uterus constitutes the intended mother’s principal contribution to pregnancy initiation with donated eggs, it is only logical that uterine factors appear to be the major recipient-related predictors of successful outcome. In the FERTILITY & STERILITY威
Zenke. Uterine factors impair donor egg success. Fertil Steril 2004.
current study, three uterine factors were examined: structural pathology, functional failure of endometrial proliferation, and operational obstacle to the transfer of embryos. These factors correspond, respectively, to the myometrium, endometrium, and cervix. Their clinical significance lies in the fact that, unlike gravidity, abnormalities can be both detected and potentially corrected before treatment begins. A focused proactive approach to the diagnosis and amelioration of these factors should lead to improved success rates. Severe structural abnormalities found exclusively in the nonpregnant group (Asherman’s syndrome, Mullerian anomalies, DES-associated T-shaped cavity, and dystrophic calcifications) have been previously reported as significant impediments to embryo implantation and successful pregnancy (5, 11–15). Other investigators also concur with our observation that the ability to restore uterine receptivity in the face of severe pathology is limited (5, 11). In our experience the embryo implantation rate in this group of patients has been abysmally low (⬍2.1%). Fibroids are the most common structural abnormality and the only one found in both the pregnant and nonpregnant groups. Whereas several studies have explored their effect on implantation and PRs in traditional IVF (16 –19), only one report addresses the influence of a prior myomectomy on donor egg cycles (5). The impact of fibroids depends on their location, number, and size. Submucous myomas encroaching on the uterine cavity are most likely to interfere with implantation and should be resected hysteroscopically (16). The role of intramural fibroids is more controversial, whereas their removal is both more invasive and prone to complications (17–19). When informed of these issues, 853
many of our patients elect to have at least one ET without surgery with an understanding that, should implantation fail or pregnancy abort, then transabdominal myomectomy would be advisable before future transfers. Thin endometrium has been associated with treatment failure (6, 7), but the exact limit below which implantation is unlikely to occur has been hard to define. In the current study, endometrium ⬍8 mm was seen solely in the nonpregnant group (Fig. 1). Women with thin lining on the screening ultrasound may benefit from a trial of hormone replacement to define the optimal regimen for endometrial proliferation. Adjuvant low-dose aspirin, prolonged vaginal micronized E2, and sidenifil vaginal suppositories have all been reported to improve outcome in cycles with thin lining (20 –22), but these strategies were of little avail in the cases reported here, most of whom had underlying uterine pathology. Isolated thin endometrium may be easier to correct than one associated with a structural abnormality. Women with severely damaged endometrium from prior chemotherapy or radiotherapy appear to benefit from prolonged treatment with pentoxifylline and tocopherol (23). Difficult ET is universally recognized as a major cause of failure in IVF and our study extends this finding to donor egg cycles (Fig. 1). Difficult ETs were seen exclusively in the nonpregnant group and had a recurrence rate of 62.5%. In our program, all patients undergo a simple trial transfer with the stiff Tomcat catheter early in the evaluation to detect cervical stenosis or tortuosity. If passage is difficult, then a trial ET with a full bladder, ultrasound guidance, and the soft Wallace catheter is performed. Should that trial also prove difficult, then placement of a laminaria tent or hysteroscopy with cervical dilation is done in the cycle preceding treatment. Cervical dilation frequently converts a difficult transfer to a moderate one but only rarely to an easy one. Dilation is of little help when the difficulty lies in a fixed and acute cervicocorporal angle rather than simple stenosis. Hysteroscopic shaving with reconstruction of the cervical canal has been described for persistent tortuosity (24). Ours is the first report to examine the interplay of the different recipient-related factors (Fig. 2). Thin endometrium frequently occurs in association with severe uterine pathology, whereas difficulty with ET is an independent predictor of outcome (25). Prospective recipients with severe uterine abnormalities or a combination of factors should be thoroughly investigated and undergo corrective procedures. These patients also need to be told that their chance of a live birth with donor eggs is markedly reduced and that a gestational carrier may be necessary. Early identification of such couples spares them the physical, emotional, and financial strain of multiple failed attempts. The profound adverse effect of the major recipient-related variables on outcome also suggests that patient mix plays as great a role in the success of donor egg programs as it does in traditional IVF (26). 854
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The design of the current study produced equivalence of most parameters between the pregnant and nonpregnant group (Table 1), bringing the recipient-related variables into sharp focus. For that very reason it is puzzling that a recent study following a similar approach has failed to uncover any recipient-related variables affecting outcome, thereby attributing the occurrence of pregnancy entirely to chance (27). However, closer scrutiny reveals several key differences between our study and that of Garcia-Velasco et al. (27) shedding light on this apparent discrepancy. The latter report combines results from two centers that potentially introduces a host of confounding factors. The patient populations also are diametrically different. In the study of Garcia-Velasco and colleagues (27), POF is the most common indication and their subjects are on average 5 years younger than ours, most of whom chose donor eggs because of advanced age. Although the age difference, in and of itself, has little impact on the outcome, several uterine pathologies, such as fibroids, Asherman’s syndrome, and postabortal calcifications, are much more likely to affect older women with ovarian function than younger women whose uteri have been exposed to the hypoestrogenic milieu of POF (28). In fact, Garcia-Velasco et al. (27) neither mention how the uterus was evaluated nor do they include uterine factor as a diagnostic category. Whereas uterine factors are relatively uncommon as the sole diagnosis, abnormalities of the uterus play a major role among the 30.1% of couples who undergo ART for multifactorial infertility (1). With traditional IVF, the live birth rate for couples with pure uterine factor is lower than that for any indication other than diminished ovarian reserve (1). The current study examines all but three of the many facets of the broadly conceived uterine and transfer factors described in the literature. Other potentially important aspects include markers of secretory endometrial transformation and their impact on the putative window of implantation, myometrial contractility during ET, subendometrial and endometrial blood flow, cervical flushing and reflux, site of deposition and direction of flow of the microdroplet containing the embryos, and the presence of blood or mucus on the catheter. Careful examination of these variables is likely to identify additional predictors of success with donor eggs and further limit the role that pure chance plays in implantation failure. In addition to the uterine variables, a difference in the number of high-grade embryos was observed between the pregnant and nonpregnant groups (Table 1). Because all the other gamete parameters are equivalent, this finding supports the hypothesis that subtle variations in sperm quality also influence the outcome of ART (7, 29). Gravidity, the only other variable found to differ, is more likely to be a marker of the severity of other infertility factors in the nonpregnant group than an independent determinant of outcome (5). The
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finding that high BMI and frequency of endometriosis are comparable is in agreement with other reports (30, 31). Does the recipients’ age matter? The high success rate of pregnancy initiation with donor eggs in women more than 40 years also has been widely accepted as prime evidence that the steep age-associated decline in pregnancy rates with traditional IVF and inseminations, which begins as early as 33 years, is due to the aging of ova rather than the uterus (1, 32–34). With traditional IVF, a decline in both embryo viability and, to a lesser extent, uterine receptivity has been reported in women above the age of 40 years (35). The finding of decreased uterine receptivity with IVF, however, cannot be extrapolated to donor egg cycles, because only in IVF does endometrial receptivity depend on the endocrine function of the ovaries, which also declines with age (36). In addressing the question of recipients’ age in donor egg cycles, most investigators have followed the lead from IVF by drawing the dividing line at 40 years. The majority of studies, including ours, show no effect at 40 years (4, 7, 27, 32, 33, 37, 38), but some studies find either subtle (2, 5, 39) or even dramatic adverse effects (10, 40). Meldrum (40) has advanced a much quoted hypothesis that, in donor egg cycles, endometrial receptivity also decreases by 40 years of age but that this decline is masked by supraphysiologic hormone replacement regimens (10). However, such a pharmacologically correctable endometrial resistance hardly compares to the inexorable aging of ova, which responds to no hormonal manipulation whatsoever (37). Rather, this resistance to the action of steroid hormones is akin to the increased gonadotropin requirement of aging ovaries. The recent report by Toner and colleagues (28) trumps prior studies by examining the entire national experience with donor eggs reported to the Society for Assisted Reproductive Technologies. A decrease in PR is detectable at 48 years of age but it becomes clear-cut only in the 50- to 54-year age group. The magnitude of the decrease in delivery rate per transfer from 40.3% in the 25- to 49-year group to 32.3% in the 50- to 54-year group is 19.8%, which is less than one-third of the 63.8% decline in the live birth rate per retrieval with traditional IVF from 36.2% in the ⬍35-year to 13.1% in the 41- to 42-year age groups (1, 28). Therefore, with donor eggs, true uterine senescence begins about 15 years later than the onset of oocyte aging and its effect on delivery rate is greatly attenuated by comparison with traditional IVF. The contradictory findings in recipients below and above the age of 40 years are attributable to differential manifestation of endometrial resistance with diverse hormonal regimens as well as the confounding effect of such age-associated uterine factors as fibroids and Asherman’s syndrome (5, 28, 39). The current study is not free of flaws, the greatest of which are its relatively small sample size, long time-frame, and last, but not least, the interminable discussion section. FERTILITY & STERILITY威
The first two drawbacks are largely offset by the matched pair design and the internal consistency of data collected by a single ART practitioner. However, finding an association between a patient characteristic and treatment outcome suggests, but does not establish, causality. The case-control format also does not provide a quantitative estimate of the putative effect of different variables on outcome. Thus, the validity of our findings depends in part on their pathophysiologic plausibility and in part on their concordance with other studies (4 – 8, 11–19). Based on these criteria, it is our contention that the three major recipient-related factors discussed qualify not just as predictors but as actual determinants of success with this therapy. In summary, uterine pathology, thin endometrium, and difficult ET are the most important recipient-related determinants of success with donor eggs. Therefore, these factors must be fully evaluated and optimized before treatment is initiated. When a combination of factors occurs or corrective strategies fail, recipients should be advised that their chance of success may be markedly reduced and that another family-building option should be seriously considered. References 1. Centers for Disease Control and Prevention. 2000 Assisted Reproductive Technology Success Rates: National Summary and Fertility Clinic Reports. Atlanta, GA: Centers for Disease Control and Prevention, December 2001. 2. Harris SE, Faddy M, Levett S, Sharma V, Gosden R. Analysis of donor heterogeneity as a factor affecting the clinical outcome of oocyte donation. Hum Fertil (Camb) 2002;5:193– 8. 3. Pados G, Camus M, Van Waesberghe L, Liebaers I, Van Sterteghem A, Devroey P. Oocyte and embryo donation: evaluation of 412 consecutive trials. Hum Reprod 1992;7:1111–7. 4. Sauer M, Paulson RJ, Ary BA, Lobo RA. Three hundred cycles of oocyte donation at the University of Southern California: assessing the effect of age and infertility diagnosis on pregnancy and implantation rates. J Assist Reprod Gen 1994;11:92– 6. 5. Moomjy M, Cholst I, Mangieri, Rosenwaks Z. Oocyte donation: insights into implantation. Fertil Steril 1999;71:15–21. 6. Check JH, Nowroozi K, Choe J, Lurie D, Dietterich C. The effect of endometrial thickness and echo pattern on in vitro fertilization outcome in donor oocyte-embryo transfer cycle. Fertil Steril 1993;59:72–5. 7. Noyes N, Hampton BS, Berkeley A, Liccardi F, Grifo J, Kray L. Factors useful in predicting the success of oocyte donation: a 3-year retrospective analysis. Fertil Steril 2001;76:92–7. 8. Cohen MA, Lindheim SR, Sauer MV. Hydrosalpinges adversely affect implantation in donor oocyte cycles. Hum Reprod 1999;14:1087–9. 9. Zenke U, Chetkowski RJ. Inclusion of heterozygotes for cystic fibrosis in the egg donor pool. Fertil Steril 2002;78:557– 61. 10. Weckstein LN, Jacobsen A, Galen D, Hampton K, Ivani K, Andres J. Improvement of pregnancy rates with oocyte donation in older recipients with the addition of progesterone vaginal suppositories. Fertil Steril 1993;60:573–5. 11. Capella-Allouc S, Morsad F, Rongieres-Bertrand C, Taylor S, Fernandez H. Hysteroscopic treatment of severe Asherman’s syndrome and subsequent fertility. Hum Reprod 1999;14:1230–3. 12. Heinonen PK, Kuismanen K, Ashorn R. Assisted reproduction in women with uterine anomalies. Eur J Obstet Reprod Biol 2000;89: 181– 4. 13. Noyes N, Liu HC, Sultan K, Rosenwaks Z. Endometrial pattern in diethylstilbestrol-exposed women undergoing in-vitro fertilization may be the most significant predictor of pregnancy outcome. Hum Reprod 1996;11:2719 –23. 14. Bahceci M, Demirel LC. Osseus metaplasia of the endometrium: a rare cause of infertility and its hysteroscopic management. Hum Reprod 1996;11:2537–9. 15. Feyles V, Moyana TN, Pierson RA. Recurrent pregnancy loss associated with endometrial hyperechoic areas (endometrial calcifications): a case report and review of the literature. Clin Exp Obstet Gynecol 2000;27:5– 8.
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16. Varasteh N, Neuwirth R, Levin B, Keltz M. Pregnancy rates after hysteroscopic polypectomy and myomectomy in infertile women. Obstet Gynecol 1999;94:168 –71. 17. Surrey ES, Lietz AK, Schoolcraft W. Impact of intramural leiomyomata in patients with a normal endometrial cavity on in vitro fertilizationembryo transfer cycle outcome. Fertil Steril 2001;75:405–10. 18. Hart R, Khalaf Y, Yeong CT, Seed P, Taylor A, Braude P. A prospective controlled study of the effect of intramural uterine fibroids on the outcome of assisted conception. Hum Reprod 2001;16:2411–7. 19. Check JH, Choe JK, Lee G, Dietterich C. The effect on IVF outcome of small intramural fibroids not compressing the uterine cavity as determined by a prospective matched control study. Hum Reprod 2002;17:1244 – 8. 20. Weckstein LN, Jacobson A, Galen D, Hampton K, Hammel J. Lowdose aspirin for oocyte donation recipients with a thin endometrium: prospective, randomized study. Fertil Steril 1998;70:599 – 600. 21. Tourgeman DE, Gentzchein E, Stanczyk FZ, Paulson RJ. Serum and tissue hormone levels of vaginally and orally administered estradiol. Am J Obstet Gynecol 1999;180:1480 –3. 22. Sher G, Fisch JD. Vaginal sildenafil (Viagra): a preliminary report of a novel method to improve uterine artery blood flow and endometrial development in patients undergoing IVF. Hum Reprod 2000;15:806 –9. 23. Ledee-Bataille N, Olivennes F, Lefaix J-L, Chaouat G, Frydman R, Delanian S. Combined treatment by pentoxifylline and tocopherol for recipient women with a thin endometrium enrolled in an oocyte donation programme. Hum Reprod 2002;17:1249 –53. 24. Noyes N, Liccardi F, Grifo J, Krey L, Berkeley A. In vitro fertilization outcome relative to embryo transfer difficulty: a novel approach to the forbidding cervix. Fertil Steril 1999;72:261–5. 25. Tomas C, Tikkinen K, Tuomivaara L, Tapanainen JS, Martikainen H. The degree of difficulty of embryo transfer is an independent factor for predicting pregnancy. Hum Reprod 2002;17:2632–5. 26. Hershlag A, Kaplan EH, Loy RA, DeCherney AH, Lavy G. Heterogeneity in patient populations explains differences in in vitro fertilization programs. Fertil Steril 1991;56:913–7. 27. Garcia-Velasco JA, Isaza V, Caligara C, Pellicer A, Remohi J, Simon C. Factors that determine discordant outcome from shared oocytes. Fertil Steril 2003;80:54– 60. 28. Toner JP, Grainger DA, Frazier LM. Clinical outcomes among recipients of donated eggs: an analysis of the U.S. national experience, 1996 –1998. Fertil Steril 2002;78:1038 – 45.
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29. Oehninger S, Chaturverdi S, Toner J, Morshedi M, Mayer J, Lanzendorf S, et al. Semen quality: is there a paternal effect on pregnancy outcome in in-vitro fertilization/intracytoplasmic sperm injection? Hum Reprod 1998; 13:2161– 4. 30. Lashen H, Ledger W, Bernal AL, Barlow D. Extremes of body mass index do not adversely affect the outcome of superovulation and invitro fertilization. Hum Reprod 1999;14:712–5. 31. Diaz I, Navarro J, Blasco L, Simon C, Pellicer A, Remohi J. Impact of stage III–IV endometriosis on recipients of sibling oocytes: matched case-control study. Fertil Steril 2000;74:31– 4. 32. Sauer MV, Paulson RJ, Lobo RA. A preliminary report on oocyte donation extending reproductive potential to women over 40. N Engl J Med 1990;323:1157– 60. 33. Navot D, Drews MR, Bergh PA, Guzman I, Karstaedt A, Scott RT, et al. Age-related decline in female fertility is not due to diminished capacity of the uterus to sustain embryo implantation. Fertil Steril 1994;61:97–101. 34. Schwartz D, Mayaux MJ, Federation CECOS. Female fecundity as a function of age: results of artificial insemination in 2190 multiparous women with azoospermic husbands. N Engl J Med 1982;306:404 – 6. 35. Chetkowski RJ, Rode RA, Burruel V, Nass TE. The effect of pituitary suppression and the women’s age on embryo viability and uterine receptivity. Fertil Steril 1991;56:1095–103. 36. Sherman BM, West JH, Korenman SG. The menopausal transition: analysis of LH, FSH, estradiol, and progesterone concentrations during menstrual cycles of older women. J Clin Endocrinol Metab 1976:42: 629 –36. 37. Check J, Askari HA, Fisher C, Vanaman L. The use of a shared donor oocyte program to evaluate the effect of uterine senescence. Fertil Steril 1994;61:252– 6. 38. Abdalla HI, Wren ME, Thomas A, Korea L. Age of the uterus does not affect pregnancy or implantation rates; a study of egg donation in women of different ages sharing oocytes from the same donor. Hum Reprod 1997;12:827–9. 39. Borini A, Bianchi L, Violini F, Maccolini A, Cattoli M, Flamigni C. Oocyte donation program: pregnancy and implantation rates in women of different ages sharing oocytes from a single donor. Fertil Steril 1996;65:94 –7. 40. Meldrum DR. Female reproductive aging ovarian and uterine factors. Fertil Steril 1993;59:1–5.
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Vol. 82, No. 4, October 2004
Transfer and uterine factors are the major recipient-related determinants of success with donor eggs Ulrike Zenke, M.D., and Ryszard J. Chetkowski, M.D. Alta Bates In Vitro Fertilization Program, Berkeley, California
Objective: To define the recipient-related determinants of outcome with donor eggs. Design: Case-control study. Setting: Community hospital-based assisted reproductive technology (ART) program. Patient(s): One hundred thirty-four embryo transfers (ETs) in which two recipients were matched to one donor. Intervention(s): Controlled ovarian hyperstimulation (COH) and ovum retrieval in donors; IVF and ET to recipients. Main Outcome Measure(s): Recipients’ age, body mass index (BMI), medical conditions, endometriosis, gravidity, uterine pathology, endometrial thickness, egg number, total motile sperm count, intracytoplasmic sperm injection (ICSI), zygote number, fertilization rate, embryos per ET, embryos frozen, embryo quality, difficulty with transfer, and ongoing pregnancies per ET. Result(s): Forty-one recipient pairs had discordant outcomes. Pregnant patients had a lower frequency (9.7% vs. 31.7%, P⫽.04) and lesser severity of uterine pathology. Endometrium ⬍8 mm was found solely in failed cycles. Pregnant women had fewer moderate or difficult ETs (9.7% vs. 31.7%, P⫽.04) and more good embryos (1.8 vs. 1.3, P⫽.03) than the nonpregnant group. Conclusion(s): Analysis of recipient pairs with discordant outcomes identifies the recipient-related predictors of success by keeping oocyte quality and the laboratory component constant. Uterine pathology, thin endometrium, transfer difficulty, and number of high-grade embryos are the principal recipient-related determinants of outcome with donor eggs. (Fertil Steril威 2004;82:850 – 6. ©2004 by American Society for Reproductive Medicine.) Key words: Egg donation, uterine factor infertility, ET, uterine receptivity, embryo implantation, endometrial thickness, donor egg recipients, aging of the uterus, donor egg outcome, uterine senescence
Received December 23, 2003; revised and accepted March 24, 2004. Presented in part at the 51st Annual Meeting of the Pacific Coast Reproductive Society, Rancho Mirage, California, April 25–27, 2003. Reprint requests: Ryszard J. Chetkowski, M.D., Alta Bates Medical Center, 2999 Regent Street, Suite 101-A, Berkeley, California 94704 (FAX: 510-649-8700; E-mail: [email protected]). 0015-0282/04/$30.00 doi:10.1016/j.fertnstert.2004. 03.057
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Pregnancy initiation with donated eggs is a common treatment for a wide spectrum of infertility conditions including advanced female age, premature ovarian failure (POF), repetitive failure of IVF, and genetic disorders. The key feature of donor egg treatment is that it permits simultaneous yet separate optimization of oocyte quantity and quality in the fertile donor, and of endometrial receptivity in the infertile recipient. For this reason it has consistently produced the highest live birth rate of all the assisted reproductive technologies (ART). Nonetheless, only 43.4% of the fresh donor egg transfers reported in the year 2000 resulted in a live birth (1). The causes of failure have proven difficult to define because of the multiple sources of heterogeneity inherent in this com-
plex process, such as egg donors, stimulation regimens, laboratory conditions, transfer techniques, and recipient characteristics (2). The recipient-related variables previously reported to affect donor egg outcome include chemotherapy and radiotherapy (3, 4), Asherman’s syndrome (5), thin endometrium (6, 7), and hydrosalpinx (5, 8). Embryo quality clearly plays a preeminent role in all assisted reproduction, including donor eggs (7), but it is also the one variable most difficult to control. Albeit egg donation may involve a more homogeneous population of ova and embryos than traditional IVF (4), marked differences in the egg factor exist even among young and fertile donors (2). When embryo implantation fails, it is often unclear
whether the failure is attributable to the egg factor or to a recipient-related variable. The current study seeks to delineate the major recipientrelated predictors of success by examining paired ovum recipients sharing ova from a single donor. Thus, the egg factor, which is determined by the donor’s intrinsic fecundity and the vagaries of a particular treatment cycle, as well as the laboratory component remain constant for each recipient pair. Focusing on recipient pairs with discordant outcomes assures that the shared ova are of sufficient quality to establish an ongoing pregnancy in one of the recipients. Therefore, the major recipient characteristics associated with failure to conceive become apparent. Obviously, factors amenable to clinical intervention are of special interest.
MATERIALS AND METHODS Between January 1992 and December 2001, 116 infertile recipients underwent a total of 134 cycles in which two women were matched to one young, healthy, fertile, anonymous, compensated egg donor at the Alta Bates In Vitro Fertilization Program. Of the 116 recipients, 12 women underwent two cycles and 3 women had three fresh transfers each. Our donor screening and donor-recipient matching strategies have been previously described (9). A typical egg donor is a married 28-year-old woman with an average of 1.5 children who undergoes 2.5 retrievals over a period of 11 months. Donors who previously produced ⱖ14 oocytes were eligible for matching to two recipients. The study adhered to the guidelines of the Declaration of Helsinki. Because no clinical interventions were performed specifically for the purpose of this study and no subjects were contacted for interview, a separate application was not made to the Committee for the Protection of Human Subjects at the Alta Bates Medical Center. All the donors and recipients consented in writing to reporting of clinical results without identifying information. The initial chart review was conducted without the reviewer’s (U.Z.) knowledge of the match status of the infertile women and their donors. The 134 treatment cycles were classified according to whether or not an ongoing pregnancy, defined as at least one intrauterine fetus with heart motion documented by ultrasound at 11–12 weeks, was established. All donors underwent controlled ovarian hyperstimulation (COH) with leuprolide acetate (LA) and hMG with standard monitoring by serum E2 and ultrasound. Oocytes were retrieved transvaginally with ultrasound-guidance 35–36 hours after the hCG trigger. The oocytes were equally and randomly assigned to the paired recipients on the day of retrieval. When an odd number of eggs were obtained, the recipient with longer tenure in the program received the extra egg. All prospective recipients had a hysterosalpingogram within 2 years and a vaginal ultrasound within 2– 4 months FERTILITY & STERILITY威
of the treatment cycle. Saline sonohysterography and diagnostic hysteroscopy were used in select cases. When present, submucous fibroids and hydrosalpinges were removed by operative hysteroscopy and laparoscopy, respectively. Trial ET and semen analysis were done in all cases. Recipients with menses underwent pituitary downregulation with LA beginning either in the midluteal phase of the previous cycle as confirmed by serum P4 or 5 days before stopping oral contraceptives (OC). After onset of bleeding, the endometrium was prepared with step-up estrogen (E) in the form of either E2 valerate given IM twice per week, transdermal E2 patches, or oral micronized E2 for 14 –28 days. Each recipient pair followed the same initial E replacement protocol. A vaginal ultrasound was done about 1 week before the anticipated ovum retrieval at which time the dose of E2 was increased if the uterine lining was ⬍9 mm. Endometrium was measured in the sagittal plane in the thickest fundal portion from one endometrial–myometrial junction to the other. Progesterone-in-oil was given IM as a single daily injection of 75 mg starting the evening before ovum retrieval; since 1993, 400 mg of P4 was added vaginally at bedtime (10). Intracytoplasmic sperm injection (ICSI) was performed for cases with male factor infertility since 1994. The embryos were graded according to blastomere number, symmetry, and the percentage of fragmentation. Embryos with ⬎3 cells at 2 days and ⱖ7 cells at 3 days after retrieval with good blastomere morphology and ⬍10% fragmentation were considered highgrade embryos. Blastocysts were considered high-grade when exhibiting a well-developed inner cell mass. All embryos were transferred transcervically in the lithotomy position by the senior author (R.J.C.). From 1992 to 1995 ET was performed with the Tomcat catheter without ultrasound guidance 2 days after retrieval. Since 1996 embryos have been replaced with the Wallace catheter with ultrasound guidance either 3 or 5 days after retrieval. Each recipient pair had embryos transferred at the same stage of development. Transfers were rated as easy, moderate, or difficult in addition to recording specific information about the use of instruments, bleeding, and other technical aspects. Easy transfers required no instrumentation. Moderate transfers included the use of a malleable Wallace stylet, mild cervical traction, as well as double transfers necessitated by retained embryos. Difficult transfers involved the use of strong countertraction, probing, or dilation of the cervical canal. Serum hCG and P4 were done 12–13 days after retrieval. The dose of P-in-oil was adjusted to maintain serum P4 ⱖ25 ng/mL at nadir. Hormonal supplementation was stopped with evidence of endogenous placental secretion, typically at 11–12 weeks. Vaginal ultrasounds were performed at 5– 6, 8 –9, and 11–12 weeks to evaluate the progress of pregnancy. At the end of the first trimester patients with ongoing pregnancies were referred for obstetrical care. 851
TABLE 1 Comparison of variables between the pregnant and nonpregnant subjects in the group with discordant outcomes. Variable Age (y)a Normal BMI (19–25 kg/m2) Prior pregnanciesa Preexisting medical conditions Endometriosis Oocyte numbera Total motile sperm (million)a ICSI Fertilization rate Number of 2PN zygotesa Embryos/transfera Frozen embryosa High grade embryosa a
Pregnant (n ⫽ 41)
Nonpregnant (n ⫽ 41)
P value
43.4 (30–51) 76% 2.2 (0–3) 12.2% 7.3% 10.6 (5–25) 174 (4.4–903) 12.2% 72.6% 7.7 (3–19) 3.78 (2–6) 1.7 (0–6) 1.8 (0–11)
43.6 (39–50) 71% 1.1 (0–3) 22.0% 19.5% 10.5 (4–24) 169 (0.1–609) 14.5% 72.9% 7.6 (2–17) 3.95 (2–6) 2.0 (0–10) 1.3 (0–11)
.62 .64 .003 .24 .10 .91 .96 .74 .84 .91 .24 .63 .03
Values are means (ranges).
Zenke. Uterine factors impair donor egg success. Fertil Steril 2004.
Statistical Analysis
Statistical tests included 2 and paired t test as appropriate, with statistical significance defined as P⬍.05.
RESULTS In the entire study population of 116 infertile women who underwent 134 fresh donor egg cycles, 61 ongoing intrauterine pregnancies were established, which corresponds to 45.5% per transfer and 52.6% per patient. Fertilization and transfer were achieved in all cases and spare embryos were frozen in 46.2% of cycles. Of the 61 ongoing pregnancies, 58 (95.1%) resulted in the birth of at least one live infant. One patient had an unexplained fetal demise in midtrimester after having a viable fetus at 11 weeks. Two patients terminated their pregnancies in midtrimester: one due to multiple fetal malformations and one due to psychological problems. Of 67 recipients pairs, 41 (61.2%) had discordant outcomes where only one recipient achieved an ongoing pregnancy. Twenty-six recipient pairs (38.8%) had concordant outcomes: in 10 pairs (14.9%) both women achieved an ongoing pregnancy and in 16 pairs (23.9%), neither woman conceived. The distribution of discordant and concordant outcomes was not different from that expected on theoretical grounds given the overall pregnancy rate (PR) per transfer. The 41 pairs of recipients with discordant outcomes underwent detailed evaluation. Table 1 lists the examined variables. The mean age did not differ and the percentage of cycles in women ⬍40 and ⬎47 years was similar in the pregnant and nonpregnant groups. No significant differences were found with regard to body mass index (BMI), preexisting medical conditions, or endometriosis. However, the mean number of prior pregnancies was higher in the pregnant than the nonpregnant group (2.2 vs. 1.1, P⫽.003). 852
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Whereas the oocyte number, total motile sperm count, the use of ICSI, fertilization rate, number of 2PN zygotes, number of embryos per transfer, and number of embryos frozen were comparable, pregnant recipients had more high-grade embryos than their nonpregnant counterparts (1.8 vs. 1.3; P⫽.03). Figure 1 shows the frequency of the three major factors: uterine pathology, thin endometrium, and ET difficulty in the two groups. Uterine pathology was both less common and less severe in the pregnant (9.8%) than in the nonpregnant group (31.7%, P⫽.04). Among pregnant women, fibroids were the only uterine abnormality: three patients had prior myomectomies without evidence of recurrence, whereas one patient had a lower uterine segment intramural fibroid. In the
FIGURE 1 Uterine pathology, thin endometrium, and transfer difficulty in the pregnant and nonpregnant subjects in the group with discordant outcomes (*P⫽.04; **P⫽.01).
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nonpregnant group, six women had a history of fibroids: four patients had prior myomectomies but one of them had recurrence with a 12-week size uterus. Two patients had intramural fibroids without encroachment on the uterine cavity.
FIGURE 2 The percentage of cycles with one, two, or three major factors (uterine pathology, thin endometrium, and transfer difficulty) in the pregnant and nonpregnant subjects in the group with discordant outcomes (*P⫽.001).
In the nonpregnant group, seven cycles were completed in women with severe uterine abnormalities such as Asherman’s syndrome, T-shaped cavity resulting from antenatal exposure to diethylstilbesterol (DES), corrected uterine septum combined with adenomyosis, and hyperechoic foci on ultrasound due to dystrophic calcifications from a prior midtrimester termination. None of the patients with severe uterine pathology ever achieved implantation while in the practice despite undergoing nine fresh and four frozen ETs with replacement of a total of 48 embryos. In her final attempt, one woman shared donor eggs with her fertile twin sister who, acting as a gestational carrier, delivered fraternal twins from transfer of just two embryos. The average endometrial thickness of 10.8 mm in the pregnant group was not statistically different from that in the nonpregnant group (9.8 mm). However, none of the pregnant patients had endometrium ⬍8 mm, whereas lining ⬍8 mm was found in six failed cycles (14.5%, P⫽.01). In five cycles, thin endometrium was associated with one of the severe uterine pathologies. Only the patient with isolated lining ⬍8 mm had previously achieved a live birth in an IVF cycle during which her endometrium measured 11 mm. A lower frequency and lesser degree of difficulty with ET was found in the pregnant compared to the nonpregnant group (9.7% vs. 31.7%, P⫽.04). In the former, four transfers were rated as moderate but none was difficult. In comparison, there were seven moderate and six difficult ETs in the nonpregnant group. Women with structural uterine abnormalities accounted for three moderate but none of the difficult ETs. Of the six women with difficult transfers in the index cycles, four underwent an additional eight ETs outside the study. Five (62.5%) of those eight transfers were also difficult. The sole patient to achieve a live birth had an easy transfer in the conception cycle. Figure 2 shows the combinations of the three major factors in the pregnant and nonpregnant groups. In the pregnant group, 9 of 41 cycles (22.0%) were associated with one factor but none had more than one factor. In contrast, in the nonpregnant group, 18 cycles (43.9%) had one factor, 5 cycles (12.2%) had two factors, and 1 cycle (2.4%) had all three factors. Thus, at least one of the three factors was implicated in 24 of 41 failed cycles (58.5%) compared to only 22.0% of the pregnancy cycles (P⫽.001).
DISCUSSION Because the uterus constitutes the intended mother’s principal contribution to pregnancy initiation with donated eggs, it is only logical that uterine factors appear to be the major recipient-related predictors of successful outcome. In the FERTILITY & STERILITY威
Zenke. Uterine factors impair donor egg success. Fertil Steril 2004.
current study, three uterine factors were examined: structural pathology, functional failure of endometrial proliferation, and operational obstacle to the transfer of embryos. These factors correspond, respectively, to the myometrium, endometrium, and cervix. Their clinical significance lies in the fact that, unlike gravidity, abnormalities can be both detected and potentially corrected before treatment begins. A focused proactive approach to the diagnosis and amelioration of these factors should lead to improved success rates. Severe structural abnormalities found exclusively in the nonpregnant group (Asherman’s syndrome, Mullerian anomalies, DES-associated T-shaped cavity, and dystrophic calcifications) have been previously reported as significant impediments to embryo implantation and successful pregnancy (5, 11–15). Other investigators also concur with our observation that the ability to restore uterine receptivity in the face of severe pathology is limited (5, 11). In our experience the embryo implantation rate in this group of patients has been abysmally low (⬍2.1%). Fibroids are the most common structural abnormality and the only one found in both the pregnant and nonpregnant groups. Whereas several studies have explored their effect on implantation and PRs in traditional IVF (16 –19), only one report addresses the influence of a prior myomectomy on donor egg cycles (5). The impact of fibroids depends on their location, number, and size. Submucous myomas encroaching on the uterine cavity are most likely to interfere with implantation and should be resected hysteroscopically (16). The role of intramural fibroids is more controversial, whereas their removal is both more invasive and prone to complications (17–19). When informed of these issues, 853
many of our patients elect to have at least one ET without surgery with an understanding that, should implantation fail or pregnancy abort, then transabdominal myomectomy would be advisable before future transfers. Thin endometrium has been associated with treatment failure (6, 7), but the exact limit below which implantation is unlikely to occur has been hard to define. In the current study, endometrium ⬍8 mm was seen solely in the nonpregnant group (Fig. 1). Women with thin lining on the screening ultrasound may benefit from a trial of hormone replacement to define the optimal regimen for endometrial proliferation. Adjuvant low-dose aspirin, prolonged vaginal micronized E2, and sidenifil vaginal suppositories have all been reported to improve outcome in cycles with thin lining (20 –22), but these strategies were of little avail in the cases reported here, most of whom had underlying uterine pathology. Isolated thin endometrium may be easier to correct than one associated with a structural abnormality. Women with severely damaged endometrium from prior chemotherapy or radiotherapy appear to benefit from prolonged treatment with pentoxifylline and tocopherol (23). Difficult ET is universally recognized as a major cause of failure in IVF and our study extends this finding to donor egg cycles (Fig. 1). Difficult ETs were seen exclusively in the nonpregnant group and had a recurrence rate of 62.5%. In our program, all patients undergo a simple trial transfer with the stiff Tomcat catheter early in the evaluation to detect cervical stenosis or tortuosity. If passage is difficult, then a trial ET with a full bladder, ultrasound guidance, and the soft Wallace catheter is performed. Should that trial also prove difficult, then placement of a laminaria tent or hysteroscopy with cervical dilation is done in the cycle preceding treatment. Cervical dilation frequently converts a difficult transfer to a moderate one but only rarely to an easy one. Dilation is of little help when the difficulty lies in a fixed and acute cervicocorporal angle rather than simple stenosis. Hysteroscopic shaving with reconstruction of the cervical canal has been described for persistent tortuosity (24). Ours is the first report to examine the interplay of the different recipient-related factors (Fig. 2). Thin endometrium frequently occurs in association with severe uterine pathology, whereas difficulty with ET is an independent predictor of outcome (25). Prospective recipients with severe uterine abnormalities or a combination of factors should be thoroughly investigated and undergo corrective procedures. These patients also need to be told that their chance of a live birth with donor eggs is markedly reduced and that a gestational carrier may be necessary. Early identification of such couples spares them the physical, emotional, and financial strain of multiple failed attempts. The profound adverse effect of the major recipient-related variables on outcome also suggests that patient mix plays as great a role in the success of donor egg programs as it does in traditional IVF (26). 854
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The design of the current study produced equivalence of most parameters between the pregnant and nonpregnant group (Table 1), bringing the recipient-related variables into sharp focus. For that very reason it is puzzling that a recent study following a similar approach has failed to uncover any recipient-related variables affecting outcome, thereby attributing the occurrence of pregnancy entirely to chance (27). However, closer scrutiny reveals several key differences between our study and that of Garcia-Velasco et al. (27) shedding light on this apparent discrepancy. The latter report combines results from two centers that potentially introduces a host of confounding factors. The patient populations also are diametrically different. In the study of Garcia-Velasco and colleagues (27), POF is the most common indication and their subjects are on average 5 years younger than ours, most of whom chose donor eggs because of advanced age. Although the age difference, in and of itself, has little impact on the outcome, several uterine pathologies, such as fibroids, Asherman’s syndrome, and postabortal calcifications, are much more likely to affect older women with ovarian function than younger women whose uteri have been exposed to the hypoestrogenic milieu of POF (28). In fact, Garcia-Velasco et al. (27) neither mention how the uterus was evaluated nor do they include uterine factor as a diagnostic category. Whereas uterine factors are relatively uncommon as the sole diagnosis, abnormalities of the uterus play a major role among the 30.1% of couples who undergo ART for multifactorial infertility (1). With traditional IVF, the live birth rate for couples with pure uterine factor is lower than that for any indication other than diminished ovarian reserve (1). The current study examines all but three of the many facets of the broadly conceived uterine and transfer factors described in the literature. Other potentially important aspects include markers of secretory endometrial transformation and their impact on the putative window of implantation, myometrial contractility during ET, subendometrial and endometrial blood flow, cervical flushing and reflux, site of deposition and direction of flow of the microdroplet containing the embryos, and the presence of blood or mucus on the catheter. Careful examination of these variables is likely to identify additional predictors of success with donor eggs and further limit the role that pure chance plays in implantation failure. In addition to the uterine variables, a difference in the number of high-grade embryos was observed between the pregnant and nonpregnant groups (Table 1). Because all the other gamete parameters are equivalent, this finding supports the hypothesis that subtle variations in sperm quality also influence the outcome of ART (7, 29). Gravidity, the only other variable found to differ, is more likely to be a marker of the severity of other infertility factors in the nonpregnant group than an independent determinant of outcome (5). The
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finding that high BMI and frequency of endometriosis are comparable is in agreement with other reports (30, 31). Does the recipients’ age matter? The high success rate of pregnancy initiation with donor eggs in women more than 40 years also has been widely accepted as prime evidence that the steep age-associated decline in pregnancy rates with traditional IVF and inseminations, which begins as early as 33 years, is due to the aging of ova rather than the uterus (1, 32–34). With traditional IVF, a decline in both embryo viability and, to a lesser extent, uterine receptivity has been reported in women above the age of 40 years (35). The finding of decreased uterine receptivity with IVF, however, cannot be extrapolated to donor egg cycles, because only in IVF does endometrial receptivity depend on the endocrine function of the ovaries, which also declines with age (36). In addressing the question of recipients’ age in donor egg cycles, most investigators have followed the lead from IVF by drawing the dividing line at 40 years. The majority of studies, including ours, show no effect at 40 years (4, 7, 27, 32, 33, 37, 38), but some studies find either subtle (2, 5, 39) or even dramatic adverse effects (10, 40). Meldrum (40) has advanced a much quoted hypothesis that, in donor egg cycles, endometrial receptivity also decreases by 40 years of age but that this decline is masked by supraphysiologic hormone replacement regimens (10). However, such a pharmacologically correctable endometrial resistance hardly compares to the inexorable aging of ova, which responds to no hormonal manipulation whatsoever (37). Rather, this resistance to the action of steroid hormones is akin to the increased gonadotropin requirement of aging ovaries. The recent report by Toner and colleagues (28) trumps prior studies by examining the entire national experience with donor eggs reported to the Society for Assisted Reproductive Technologies. A decrease in PR is detectable at 48 years of age but it becomes clear-cut only in the 50- to 54-year age group. The magnitude of the decrease in delivery rate per transfer from 40.3% in the 25- to 49-year group to 32.3% in the 50- to 54-year group is 19.8%, which is less than one-third of the 63.8% decline in the live birth rate per retrieval with traditional IVF from 36.2% in the ⬍35-year to 13.1% in the 41- to 42-year age groups (1, 28). Therefore, with donor eggs, true uterine senescence begins about 15 years later than the onset of oocyte aging and its effect on delivery rate is greatly attenuated by comparison with traditional IVF. The contradictory findings in recipients below and above the age of 40 years are attributable to differential manifestation of endometrial resistance with diverse hormonal regimens as well as the confounding effect of such age-associated uterine factors as fibroids and Asherman’s syndrome (5, 28, 39). The current study is not free of flaws, the greatest of which are its relatively small sample size, long time-frame, and last, but not least, the interminable discussion section. FERTILITY & STERILITY威
The first two drawbacks are largely offset by the matched pair design and the internal consistency of data collected by a single ART practitioner. However, finding an association between a patient characteristic and treatment outcome suggests, but does not establish, causality. The case-control format also does not provide a quantitative estimate of the putative effect of different variables on outcome. Thus, the validity of our findings depends in part on their pathophysiologic plausibility and in part on their concordance with other studies (4 – 8, 11–19). Based on these criteria, it is our contention that the three major recipient-related factors discussed qualify not just as predictors but as actual determinants of success with this therapy. In summary, uterine pathology, thin endometrium, and difficult ET are the most important recipient-related determinants of success with donor eggs. Therefore, these factors must be fully evaluated and optimized before treatment is initiated. When a combination of factors occurs or corrective strategies fail, recipients should be advised that their chance of success may be markedly reduced and that another family-building option should be seriously considered. References 1. Centers for Disease Control and Prevention. 2000 Assisted Reproductive Technology Success Rates: National Summary and Fertility Clinic Reports. Atlanta, GA: Centers for Disease Control and Prevention, December 2001. 2. Harris SE, Faddy M, Levett S, Sharma V, Gosden R. Analysis of donor heterogeneity as a factor affecting the clinical outcome of oocyte donation. Hum Fertil (Camb) 2002;5:193– 8. 3. Pados G, Camus M, Van Waesberghe L, Liebaers I, Van Sterteghem A, Devroey P. Oocyte and embryo donation: evaluation of 412 consecutive trials. Hum Reprod 1992;7:1111–7. 4. Sauer M, Paulson RJ, Ary BA, Lobo RA. Three hundred cycles of oocyte donation at the University of Southern California: assessing the effect of age and infertility diagnosis on pregnancy and implantation rates. J Assist Reprod Gen 1994;11:92– 6. 5. Moomjy M, Cholst I, Mangieri, Rosenwaks Z. Oocyte donation: insights into implantation. Fertil Steril 1999;71:15–21. 6. Check JH, Nowroozi K, Choe J, Lurie D, Dietterich C. The effect of endometrial thickness and echo pattern on in vitro fertilization outcome in donor oocyte-embryo transfer cycle. Fertil Steril 1993;59:72–5. 7. Noyes N, Hampton BS, Berkeley A, Liccardi F, Grifo J, Kray L. Factors useful in predicting the success of oocyte donation: a 3-year retrospective analysis. Fertil Steril 2001;76:92–7. 8. Cohen MA, Lindheim SR, Sauer MV. Hydrosalpinges adversely affect implantation in donor oocyte cycles. Hum Reprod 1999;14:1087–9. 9. Zenke U, Chetkowski RJ. Inclusion of heterozygotes for cystic fibrosis in the egg donor pool. Fertil Steril 2002;78:557– 61. 10. Weckstein LN, Jacobsen A, Galen D, Hampton K, Ivani K, Andres J. Improvement of pregnancy rates with oocyte donation in older recipients with the addition of progesterone vaginal suppositories. Fertil Steril 1993;60:573–5. 11. Capella-Allouc S, Morsad F, Rongieres-Bertrand C, Taylor S, Fernandez H. Hysteroscopic treatment of severe Asherman’s syndrome and subsequent fertility. Hum Reprod 1999;14:1230–3. 12. Heinonen PK, Kuismanen K, Ashorn R. Assisted reproduction in women with uterine anomalies. Eur J Obstet Reprod Biol 2000;89: 181– 4. 13. Noyes N, Liu HC, Sultan K, Rosenwaks Z. Endometrial pattern in diethylstilbestrol-exposed women undergoing in-vitro fertilization may be the most significant predictor of pregnancy outcome. Hum Reprod 1996;11:2719 –23. 14. Bahceci M, Demirel LC. Osseus metaplasia of the endometrium: a rare cause of infertility and its hysteroscopic management. Hum Reprod 1996;11:2537–9. 15. Feyles V, Moyana TN, Pierson RA. Recurrent pregnancy loss associated with endometrial hyperechoic areas (endometrial calcifications): a case report and review of the literature. Clin Exp Obstet Gynecol 2000;27:5– 8.
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Uterine factors impair donor egg success
Vol. 82, No. 4, October 2004