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Factors that determine discordant outcome from shared oocytes
FERTILITY AND STERILITY威 VOL. 80, NO. 1, JULY 2003
IN VITRO FERTILIZATION
Copyright ©2003 American Society for Reproductive Medicine Published by Elsevier Inc. Printed on acid-free paper in U.S.A.
Factors that determine discordant outcome from shared oocytes Juan A. Garcia-Velasco, M.D.,a Vero´nica Isaza, M.D.,a Cinthia Caligara, M.D.,b Antonio Pellicer, M.D.,b,c Jose´ Remohı´, M.D.,b,c and Carlos Simo´n, M.D.b,c Instituto Valenciano de Infertilidad (IVI), Madrid and Valencia, Spain
Objective: To investigate the factors that may be related to pregnancy in oocyte recipients who shared oocytes from the same donor and showed discordant pregnancy outcome. Design: Matched pair analysis. Setting: IVF academic center. Patient(s): Five hundred forty-two oocyte donation cycles that shared oocytes from 197 donors with discordant outcome. Intervention(s): Egg donation and embryo transfer. Main Outcome Measure(s): Pregnancy rate and implantation rate. Result(s): Three hundred sixty-five matched-paired discordant outcome oocyte recipients were analyzed. Pregnant and nonpregnant recipients were similar in terms of age, serum E2 levels, endometrial thickness, indications for oocyte donation, and abnormal sperm parameters. No differences were found in the number of oocytes received per patient, fertilization rate, IVF/intracytoplasmic sperm injection (ICSI) distribution, embryo quality, or on embryo transfer difficulty. Conclusion(s): Discordant pregnancy outcome could not be explained by the different egg recipients and cycle factors studied. In addition to chance, other factors must be investigated that could explain discordant outcome in egg recipients sharing oocytes from single donors. (Fertil Steril威 2003;80:54 – 60. ©2003 by American Society for Reproductive Medicine.) Key Words: Oocyte donation, discordant outcome, sibling oocytes
Received September 4, 2002; revised and accepted December 9, 2002. Reprint requests: Juan A. Garcia-Velasco, M.D., IVIMadrid, C/Santiago de Compostela 88, 28035, Madrid, Spain (FAX: 34 91 386 7133; E-mail: [email protected]). a Instituto Valenciano de Infertilidad (IVI), Madrid. b Instituto Valenciano de Infertilidad (IVI), Valencia. c Department of Pediatrics, Obstetrics and Gynecology, Valencia University School of Medicine, Valencia, Spain. 0015-0282/03/$30.00 doi:10.1016/S0015-0282(03) 00545-4
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Oocyte donation is a common treatment option for a wide spectrum of infertility conditions, with a growing number of clinical indications (1, 2). Multiple prognostic factors have been studied that might affect the final outcome of the oocyte donation, some of them in the oocyte donors and others in their recipients. Basically, donor age (3), recipient age (2, 4), endometrial thickness and pattern (5, 6), and serum hormone measurements (5, 7) are among the most studied factors, but no clear-cut conclusions have been reached yet. When oocyte recipients share oocytes from a single donor and at least one of them achieves pregnancy whereas the others do not, this provides us with an excellent opportunity to study factors in oocyte recipients that may explain the discordant results. Because they share oocytes from the same donor, any factor affecting the oocyte is excluded. Most previous studies have focused on the effects of age on the egg
recipient (uterus senescence) (8 –11). Only one study (12) has addressed the possible prognostic factors in oocyte recipients who shared oocytes from single donors and who showed discordant outcome. They found a trend toward a lower pregnancy rate when embryo transfer was difficult or when male-associated factor was present, but it did not reach statistically significant differences. The present study was conducted to investigate the factors that may be related to pregnancy in oocyte recipients who shared oocytes from the same donor and showed discordant pregnancy outcome.
MATERIALS AND METHODS Study Design A matched case-control study was performed on 542 oocyte donation cycles that shared oocytes with discordant outcome, at
IVI-Madrid and Instituto Valenciano de Infertilidad from September 1999 until May 2001. Discordant outcome was established when at least one of the oocyte recipients from the same donor achieved pregnancy whereas the others did not. Recipients were divided into two groups: group 1 (278 cycles) who had a positive pregnancy outcome, and group 2 (264 cycles), who did not achieve pregnancy. Recipients from the pregnant group were 37.9 ⫾ 0.3 years old whereas recipients from the nonpregnant group were 38.2 ⫾ 0.3 years old. No Institutional Review Board approval was obtained as it was not required for this type of study.
Oocyte Donors All our donors volunteered altruistically, after being thoroughly informed, to donate their oocytes and fulfil the criteria to be admitted in our oocyte donation program. In short, they were 18 –35 years old, with complete medical history, which included current or past exposure to radiation or hazardous chemical substances, IV drug abuse, and past reproductive history. All had a normal physical and gynecological examination, no family history of hereditary or chromosomal diseases, normal karyotype, and negative screening for sexually transmitted diseases (STDs). They all received a long protocol of down-regulation with a GnRH-agonist (GnRH-a) (Decapeptyl 0.1 mg, Ipsen Pharma, Barcelona, Spain). Transvaginal ultrasound was performed to ascertain ovarian quiescence on the first 3 days of menses and then, controlled ovarian hyperstimulation was started as previously described (2). Briefly, they received 300 IU/day of urinary follicle-stimulating hormone (uFSH) for the first 3 days and then 150 IU/day until the mean leading follicles where ⬎18 mm in diameter. Human chorionic gonadotrophin (10,000 IU) was then administered and ovarian puncture was performed 36 hours afterward. Each anonymous donor was phenotypically matched with at least two potential recipients. Oocytes were evenly distributed according to their quality and maturity.
Oocyte Recipients Oocyte recipients entered our oocyte donation program due to one of the following diagnostic groups: premature ovarian failure/menopause (n ⫽ 235), failure to achieve pregnancy after at least four cycles of assisted reproduction techniques (ART) (n ⫽ 154), genetic or chromosomal disorders (n ⫽ 8), low response to controlled ovarian hyperstimulation (COH) (n ⫽ 111), recurrent miscarriage (n ⫽ 11), and other disorders (n ⫽ 23). Semen analysis was performed on each recipient’s husband and classified according to World Health Organization criteria (13). All oocyte recipients were taking hormone replacement therapy (HT), as previously described (14). Briefly, in patients with ovarian function, GnRH-a (Decapeptyl 3.75 mg) was administered in the midluteal phase of the previous cycle. The HT was started on the first day of the cycle with increasing doses of E2 valerate (Progynova, Schering Spain, FERTILITY & STERILITY威
Madrid, Spain), which was given as follows: 2 mg/day for the first 8 days of the cycle, followed by 4 mg/day for the next 3 days, and then 6 mg/day was continued until the oocyte donation was available or until the patient had vaginal spotting, in which case the cycle was canceled. On the 15th or 16th day since the beginning of HT, a transvaginal ultrasound was performed to measure endometrial thickness and serum E2 levels were obtained. When the oocyte donation was available the potential for normal fertilization was assessed by semen analysis or previously available fertilization data. Couples were offered the opportunity to undergo intracytoplasmic sperm injection (ICSI) if there was some evidence that low fertilization or fertilization failure could occur. Micronized P (800 mg/day, intravaginal) (Progeffik, Effik Laboratories, Madrid, Spain) was administered starting the day of oocyte donation, and embryo transfer was performed according to each patient’s program on day 2, 3, or 6 of embryo cleavage. Embryo transfer was performed on day 6 after embryo co-culture with epithelial endometrial cells as described elsewhere (15). On the second day of cleavage all embryos were classified according to the number of blastomeres and cytoplasmic fragmentation (grade 1: 0%, grade 2: ⱕ25%, grade 3: 26%– 50%, grade 4: 51%–75%, grade 5: ⬎75% of the embryo surface), as well as symmetry of blastomeres (grade 1: all blastomeres with similar size, grade 2: 75% of blastomeres symmetric, grade 3: ⬍50% with similar size) (16). Only good quality embryos were transferred (ⱖ4 blastomeres and ⬍25% of fragmentation with grade 1–2 of symmetry of blastomeres). Serum -hCG was measured the 14th day after the oocyte donation and 2 weeks later clinical pregnancy was confirmed by visualization of a gestational sac by means of a transvaginal ultrasound. Only patients with discordant outcome who shared oocytes from the same donor were included in this study.
Statistical Analysis When a pair of recipients with discordant outcome shared oocytes from a single donor, the pregnant recipient’s characteristics were compared with the nonpregnant recipient. If more than two oocyte recipients shared oocytes from a single donor, patients were matched with all the discordant ones from the same donor (Table 1). If, for example, one donor gave oocytes to four different patients, the following possibilities analyzed were: [1] one pregnant and three nonpregnant, thus three paired couples; [2] two pregnant and two nonpregnant, thus four paired couples; [3] three pregnant and one nonpregnant, thus three paired couples. Data were expressed as mean ⫾ SEM or percentages when appropriate. A value of P⬍.05 was considered significant. Statistical calculations were performed using Sigma Stat for Windows, version 2.0 (Jandel Scientific Corporation, San Rafael, CA). 55
TABLE 1 Matched pairs of egg recipients with discordant outcome. No. recipients/donor
Oocyte possibilities (matched from same donor) ⫽ n
2 3
1 pregnant/1 1 pregnant/2 2 pregnant/1 2 pregnant/2 3 pregnant/1 1 pregnant/3 4 pregnant/1 1 pregnant/4 3 pregnant/2 3 pregnant/3 6 pregnant/2 Total oocyte
4
5
6 8
nonpregnant (1 matched pair) ⫽ 94 nonpregnant (2 matched pairs) ⫽ 32 nonpregnant (2 matched pairs) ⫽ 43 nonpregnant (4 matched pairs) ⫽ 7 nonpregnant (3 matched pairs) ⫽ 7 nonpregnant (3 matched pairs) ⫽ 4 nonpregnant (4 matched pairs) ⫽ 2 nonpregnant (4 matched pairs) ⫽ 1 nonpregnant (6 matched pairs) ⫽ 2 nonpregnant (6 matched pairs) ⫽ 4 nonpregnant (12 matched pairs) ⫽ 1 donations ⫽ 197
No. matched pairs 94 ⫻ 1 ⫽ 94 32 ⫻ 2 ⫽ 64 43 ⫻ 2 ⫽ 86 7 ⫻ 4 ⫽ 28 7 ⫻ 3 ⫽ 21 4 ⫻ 3 ⫽ 12 2⫻4⫽8 1⫻4⫽4 2 ⫻ 6 ⫽ 12 4 ⫻ 6 ⫽ 24 1 ⫻ 12 ⫽ 12 Total matched pairs ⫽ 365
Garcia-Velasco. Discordant outcome in shared oocyte donation. Fertil Steril 2003.
Both pregnant and nonpregnant matched recipients were similar in terms of age (37.9 ⫾ 0.3 vs. 38.1 ⫾ 0.3 years), serum E2 levels (318.0 ⫾ 15.9 vs. 371.0 ⫾ 20.1 pg/mL), and endometrial thickness (9.2 ⫾ 0.1 vs. 9.2 ⫾ 0.1 mm). No differences were found in terms of the indications for the oocyte donation (Table 2).
nonpregnant group (P ⫽ not significant [NS]). Table 3 shows the distribution of semen anomalies, with no statistical differences between groups. In azoospermic men, spermatozoa from epididymal aspirate or testicular biopsy was used in a similar percentage in both groups (32% of the pregnant oocyte recipients and 33.3% of the nonpregnant recipients). In the remaining azoospermic men in whom no spermatozoa could be retrieved in the testicular biopsy, donor semen was used. Frozen semen samples were used in 89.7% of the pregnant group and in 84.6% of the nonpregnant group (P ⫽ NS). For further analysis, raw data on semen pathology before matching and pairing of egg recipients showed similar pregnancy rates (P ⫽ NS) among groups (data not shown).
Semen analysis from couples showed that it was pathological in 64.9% of the pregnant group and 61.4% in the
The mean number of oocytes received per patient was 7.9 ⫾ 0.1 in the pregnant group vs. 8.1 ⫾ 0.1 in the nonpregnant
RESULTS Oocytes from 197 oocyte donors where shared by 542 recipients, of which 278 conceived. We had a mean of 2.8 oocyte recipients per donor, therefore when there were more than 2 oocyte recipients per donor, each pregnant recipient was paired with each nonpregnant recipient, resulting in 365 matched-paired discordant outcome oocyte recipients (Table 1).
TABLE 2 General characteristics of matched-paired egg recipients. Pregnant oocyte recipients (n ⫽ 365) Age (y)a Serum E2 level (pg/mL)a Endometrial thickness (mm)a Indications for oocyte donationa Premature ovarian failure/menopause (%) Chromosomal/genetic diseases (%) Failure to conceive after ⱖ4 ART cycles (%) Low response (%) Repeated miscarriage (%) Others (%) a
37.9 ⫾ 0.3 318.0 ⫾ 15.9 9.2 ⫾ 0.1 163/365 (44.5) 5/365 (1.5) 106/365 (29.1) 64/365 (17.6) 8/365 (2.2) 19/365 (5.1)
Nonpregnant oocyte recipients (n ⫽ 365) 38.1 ⫾ 0.3 371.0 ⫾ 20.1 9.2 ⫾ 0.1 162/365 (44.3) 7/365 (1.9) 99/365 (27.2) 72/365 (19.7) 9/365 (2.5) 16/365 (4.4)
P is not significant.
Garcia-Velasco. Discordant outcome in shared oocyte donation. Fertil Steril 2003.
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TABLE 3 Male-associated factor of matched-paired egg recipients. Pregnant oocyte recipients (n ⫽ 365) Semen analysisa Normozoospermic (%) Asthenozoospermic Oligozoospermic Teratozoospermic Oligoteratozoospermic Oligoasthenozoospermic Astenoteratozoospermic Oligoasthenoteratozoospermic Azoospermia Epididymal aspirate/testicular biopsy Donor semen Frozen semen samplesa a
Nonpregnant oocyte recipients (n ⫽ 365)
128/365 (35.1) 120/365 (32.9) 5/365 (1.4) 2/365 (0.5) 0/365 (0) 50/365 (13.7) 10/365 (2.7) 25/365 (6.8) 25/365 (6.8) 8 (32.0)
141/365 (38.6) 95/365 (26.0) 12/365 (3.3) 2/365 (0.6) 2/365 (0.6) 69/365 (18.8) 16/365 (4.4) 16/365 (4.4) 12/365 (3.4) 4 (33.3)
17(68.0) 327/365 (89.7)
8 (66.6) 309/365 (84.6)
Embryo transfer was performed on day 2 of embryo cleavage in 61.7% of the pregnant group and in 63.0% of the nonpregnant group and in day 3 of cleavage in 21.6% and 27.9%, respectively (P ⫽ NS). A significantly higher number of day 6 embryo transfer was performed in the pregnant group when compared with the nonpregnant patients (16.6% vs. 9.0%, P⬍.05). Soft catheter for embryo replacement (Delphin, Gynetics, Hamont-Achel, Belgium) was used in 90.6% of embryo transfers in the pregnant group and in 89.9% of the nonpregnant group. A stiff catheter was used in 9.4% of the pregnant group and in 10.1% of the nonpregnant group; a catheter with a rigid outer sheath (Frydman, Gynetics) in 8.1% vs. 9.5% and a steel catheter was required in 1.3% vs. 0.6%, respectively (P ⫽ NS). Cervical tenaculum was required in only 0.7% of embryo transfers in the pregnant and in 0.6% of the nonpregnant group (P ⫽ NS).
DISCUSSION
P is not significant.
Garcia-Velasco. Discordant outcome in shared oocyte donation. Fertil Steril 2003.
group (P ⫽ NS). Fertilization was performed by conventional IVF or ICSI in 28.2% and 71.8% of the pregnant group and in 23.4% and 76.8% in the nonpregnant group, respectively (P ⫽ NS). Fertilization rate in ICSI couples was similar in both groups (83.6 ⫾ 0.8 vs. 82.1 ⫾ 0.9), as well as in IVF couples (78.6% vs. 76.1%). A similar number of good quality embryos were transferred in both groups of patients (2.8 ⫾ 0.03 vs. 2.7 ⫾ 0.03) (Table 4).
Oocyte recipients who share oocytes from a single donor and have discordant pregnancy outcome allows the assessment of several prognostic factors in the recipient that may be related to the different cycle outcome. Because at least one of the recipients conceived, oocytes have been proved to be good enough to achieve a clinical pregnancy, thus oocyte quality should be guaranteed. Four basic factors in oocyte recipients were studied: [1] demographic characteristics of oocyte recipients (age, indications for oocyte donation, serum E2 level, endometrial thickness), [2] male-associated factor, [3] oocyte donation cycle outcome, and [4] difficulty
TABLE 4 Cycle outcome and embryo transfer of matched-paired egg recipients.
No. oocytes received per couple ICSI couples ICSI fertilization rate IVF fertilization rate No. good quality embryos transferred Day of embryo transfer (%) 2 3 6 Embryo replacement catheter Soft (Delphin) Rigid: Frydman Metallic Tenaculum used at ET
Pregnant oocyte recipients (n ⫽ 365)
Nonpregnant oocyte recipients (n ⫽ 365)
P value
7.9 ⫾ 0.1 262/365 (71.8) 83.6% 78.6% 2.8 ⫾ 0.03
8.1 ⫾ 0.1 280/365 (76.8) 82.1% 76.1% 2.7 ⫾ 0.03
NS NS NS NS NS
225 (61.7) 79 (21.6) 61 (16.7)
230 (63.0) 102 (27.9) 33 (9.0)
331 (90.6) 34 (9.4) 8.1% 1.3% 3/365 (0.7)
328 (89.9) 37 (10.1) 9.5% 0.6% 2/365 (0.6)
NS NS .01 NS
NS
NS ⫽ not significant. Garcia-Velasco. Discordant outcome in shared oocyte donation. Fertil Steril 2003.
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of embryo transfer. None of these factors were found to be significantly related to pregnancy outcome. Conflicting reports on the influence of uterine age on pregnancy rate have been published (8 –11, 17). The different conclusions reached may be related to different study designs. On a previously randomized study from our group (9) we failed to show any relationship between the age of the recipient and pregnancy rate. Even after further analysis of different age subsets performed on our current series (data not shown), no differences were found between pregnant and nonpregnant recipients. Again, no differences were found according to whether ovarian function was present or absent, as previously described (17–19). Pregnancy outcome does not depend on the indication for oocyte donation, as equal distribution of the diagnostic groups was found between the two groups. Oocyte donation is an invaluable therapeutic option for a growing list of clinical indications, yielding excellent results (2). Serum E2 levels and endometrial thickness are markers routinely used to ascertain adequate endometrial preparation after exogenous HT. However, other retrospective studies (5, 7) showed that neither serum E2 level nor endometrial thickness was able to predict implantation in oocyte recipients. In the current study, we failed again to show a relationship between serum E2 levels or endometrial thickness with pregnancy outcome. We also analyzed different endometrial thickness and serum E2 levels subsets (data not shown). None of the recipients showed an endometrial thickness ⬍4 mm or serum E2 levels ⬍100 pg/mL, and we could not find any statistically significant differences among different subsets, confirming our previous study (5). Paternal influence in embryo development and cycle outcome continues to be debated. Two main mechanisms could be involved: [1] paternal transcriptional products after embryonic gene activation at the 4- to 8-cell stage (20) and [2] epigenetic factors, such as components transmitted by spermatozoa or the pattern of calcium signaling. A deleterious effect of the ICSI procedure itself seems unlikely, as it has been shown that bovine oocytes develop at the same rate to blastocyst stage after ICSI as compared with that of control oocytes (21). This has been confirmed with human oocytes in a prospective, randomized trial (22). Some investigators have claimed that ICSI cycles yield a lower percentage of blastocysts when compared to IVF cycles (23), suggesting a negative paternal effect on embryo development. However, sperm parameters do not seem to correlate with the outcome of ICSI treatment (24, 25). In fact, conventionally used semen parameters do not provide information about DNA quality in the sperm (26). In addition, fertilization rates and embryo morphology are similar in patients undergoing ICSI and IVF (27–29). In contrast to Nasseri et al. (12), we did not find any adverse effect with the use of ICSI, either with the use of 58
Garcia-Velasco et al.
fresh or frozen semen samples. These results are in agreement with a previous study in which no differences in pregnancy, implantation, or miscarriage rates were found between patients with oligoasthenozoospermia treated by ICSI and normozoospermic patients treated by conventional IVF in an oocyte donation program (30). Because our matched-paired data did not show significant differences in male factor, we also analyzed our raw data before matching and pairing, and could not find any statistically significant difference either, although this could be underpowered due to the small sample size in some groups. In addition, because the inclusion criteria for this study may not reflect the general oocyte recipient population, concerns about biased data could arise. However, male pathology was equally distributed on both pregnant and nonpregnant recipients. Still, we compared egg donation outcome between epididymal aspirate/testicular biopsy in the study group and our general oocyte recipient couples, during the study period. We performed 21 egg donations with epididymal aspirate/testicular biopsy, achieving 12 clinical pregnancies, which is similar to the pregnancy rate in this study (P ⫽ NS) and with our general egg donation program results (2). Therefore, even in the presence of severe male-associated factor there seems to be no deleterious effect in pregnancy rate, as it has been previously stated (30). Minor sperm deficiencies may be compensated with excellent oocyte quality, thus diminishing the impact of the male factor in the outcome. However, further studies are required to reach a firm conclusion in this regard. Approximately the same number of oocytes were assigned to each paired receptor and no differences were found in fertilization rates between groups, as expected in oocytes obtained from young and healthy volunteers. As part of an institutional policy, only good quality embryos are transferred in our oocyte donation program, otherwise embryo transfer is canceled. Conversely, no differences were found in embryo quality between groups. There were more blastocyst transfers in the pregnant group compared with the nonpregnant group (P⬍.05). However, this assertion should be taken cautiously as the study was not designed to demonstrate a difference in the day of embryo transfer and that these data are a retrospective analysis of clinical records. A previous study suggested that blastocyst transfer improves pregnancy rate in couples with implantation failure undergoing ovum donation, mostly due to a better embryo selection (15). Other investigators have suggested that blastocyst transfers in oocyte recipients are highly effective and can be used to decrease multiple pregnancy rates, as it allows better embryo selection while decreasing the number of embryos transferred (31, 32). A possible explanation for the higher pregnancies achieved with blastocyst transfer could be due to the better synchrony between embryo and endometrial development. Despite the fact that our findings may suggest that a higher
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Vol. 80, No. 1, July 2003
pregnancy rate can be achieved with blastocyst transfers compared to day 2 embryo transfer, only through prospective, randomized studies that compare early embryo transfer vs. blastocyst transfers will allow us to reach that conclusion. Two recently published studies of this type on IVF couples (33, 34) reached discordant conclusions, therefore this is still a matter of debate. A traumatic embryo transfer that requires the use of rigid catheters and cervical tenaculum has been found to negatively influence both implantation and pregnancy rates (35). A similar distribution in easy and difficult embryo transfers was observed in both groups of patients, thus we can rule out any bias in this regard. In addition to chance, other factors that explain the discordant pregnancy outcome in oocyte recipients sharing oocytes must be sought. There is some evidence that even young healthy women produce a high number of chromosomally abnormal embryos. In a retrospective case analysis of preimplantation genetic diagnosis performed on embryos from oocyte donors, a high number of chromosome aneuploidy was found (36). Both trisomies and monosomies were detected and could not be predicted on embryo morphology. Previous work by Munne´ et al. (37) has demonstrated that preimplantation genetic diagnosis may improve implantation rates by selecting chromosomally normal embryos. Thus, preimplantation genetic diagnosis on embryos from egg donors may further improve implantation and pregnancy rates. We can only speculate that more chromosomally abnormal embryos were present in egg recipients that did not achieve pregnancy compared with recipients who conceived. Further studies are needed to confirm this hypothesis and to verify whether these abnormalities are due to chromosomally abnormal oocytes or occur after syngamy; young, healthy egg donors with normal karyotype do not guarantee a normal conceptus. In conclusion, discordant pregnancy outcome in oocyte recipients sharing oocytes from single donors cannot be explained by recipient’s age, indication for oocyte donation, serum E2 level, or endometrial thickness. Male-associated factor did not seem to influence pregnancy outcome. Thus, commonly recorded recipient and cycle factors do not explain discordant cycle outcomes, which could be influenced by chance or some as yet untested factors. Future preimplantation genetic diagnosis studies may demonstrate whether chromosomally abnormal embryos can explain the discordant outcome in egg recipients. References 1. Kalfoglou AL, Glittelsohn J. A qualitative follow-up study of women’s experiences with oocyte donation. Hum Reprod 2000;15:798 –805. 2. Remohı´ J, Gartner B, Gallardo E, Yalil S, Simo´n C, Pellicer A. Pregnancy and birth rates after oocyte donation. Fertil Steril 1997;67: 717–23. 3. Stolwijk A, Zielhuis G, Sauer M, Hamilton CJ, Paulson RJ. The impact of the woman’s age on the success of standard and donor in vitro fertilization. Fertil Steril 1997;67:702–10.
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35. 36. 37.
Meuleman C, et al. A prospective randomized study: day 2 versus day 5 embryo transfer. Hum Reprod 2002;17:1507–12. Rienzi L, Ubaldi F, Iacobelli M, Ferrero S, Minasi MG, Martinez F, et al. Day 3 embryo transfer with combined evaluation at the pronuclear and cleavage stages compares favourably with day 5 blastocyst transfer. Hum Reprod 2002;17:1852–5. Schoolcraft WB, Surrey ES, Gardner DK. Embryo transfer: techniques and variables affecting success. Fertil Steril 2001;76:863–70. Nelson JR, Feinman M, Wilcox J, Batzofin J. Preimplantation genetic diagnosis in embryos created from oocyte donation. Fertil Steril 2001; 76(Suppl):S76. Munne´ S, Cohen J, Sable D. Preimplantation genetic diagnosis for advanced maternal age and other indications. Fertil Steril 2002;78: 234 –6.
Discordant outcome in shared oocyte donation
Vol. 80, No. 1, July 2003
IN VITRO FERTILIZATION
Copyright ©2003 American Society for Reproductive Medicine Published by Elsevier Inc. Printed on acid-free paper in U.S.A.
Factors that determine discordant outcome from shared oocytes Juan A. Garcia-Velasco, M.D.,a Vero´nica Isaza, M.D.,a Cinthia Caligara, M.D.,b Antonio Pellicer, M.D.,b,c Jose´ Remohı´, M.D.,b,c and Carlos Simo´n, M.D.b,c Instituto Valenciano de Infertilidad (IVI), Madrid and Valencia, Spain
Objective: To investigate the factors that may be related to pregnancy in oocyte recipients who shared oocytes from the same donor and showed discordant pregnancy outcome. Design: Matched pair analysis. Setting: IVF academic center. Patient(s): Five hundred forty-two oocyte donation cycles that shared oocytes from 197 donors with discordant outcome. Intervention(s): Egg donation and embryo transfer. Main Outcome Measure(s): Pregnancy rate and implantation rate. Result(s): Three hundred sixty-five matched-paired discordant outcome oocyte recipients were analyzed. Pregnant and nonpregnant recipients were similar in terms of age, serum E2 levels, endometrial thickness, indications for oocyte donation, and abnormal sperm parameters. No differences were found in the number of oocytes received per patient, fertilization rate, IVF/intracytoplasmic sperm injection (ICSI) distribution, embryo quality, or on embryo transfer difficulty. Conclusion(s): Discordant pregnancy outcome could not be explained by the different egg recipients and cycle factors studied. In addition to chance, other factors must be investigated that could explain discordant outcome in egg recipients sharing oocytes from single donors. (Fertil Steril威 2003;80:54 – 60. ©2003 by American Society for Reproductive Medicine.) Key Words: Oocyte donation, discordant outcome, sibling oocytes
Received September 4, 2002; revised and accepted December 9, 2002. Reprint requests: Juan A. Garcia-Velasco, M.D., IVIMadrid, C/Santiago de Compostela 88, 28035, Madrid, Spain (FAX: 34 91 386 7133; E-mail: [email protected]). a Instituto Valenciano de Infertilidad (IVI), Madrid. b Instituto Valenciano de Infertilidad (IVI), Valencia. c Department of Pediatrics, Obstetrics and Gynecology, Valencia University School of Medicine, Valencia, Spain. 0015-0282/03/$30.00 doi:10.1016/S0015-0282(03) 00545-4
54
Oocyte donation is a common treatment option for a wide spectrum of infertility conditions, with a growing number of clinical indications (1, 2). Multiple prognostic factors have been studied that might affect the final outcome of the oocyte donation, some of them in the oocyte donors and others in their recipients. Basically, donor age (3), recipient age (2, 4), endometrial thickness and pattern (5, 6), and serum hormone measurements (5, 7) are among the most studied factors, but no clear-cut conclusions have been reached yet. When oocyte recipients share oocytes from a single donor and at least one of them achieves pregnancy whereas the others do not, this provides us with an excellent opportunity to study factors in oocyte recipients that may explain the discordant results. Because they share oocytes from the same donor, any factor affecting the oocyte is excluded. Most previous studies have focused on the effects of age on the egg
recipient (uterus senescence) (8 –11). Only one study (12) has addressed the possible prognostic factors in oocyte recipients who shared oocytes from single donors and who showed discordant outcome. They found a trend toward a lower pregnancy rate when embryo transfer was difficult or when male-associated factor was present, but it did not reach statistically significant differences. The present study was conducted to investigate the factors that may be related to pregnancy in oocyte recipients who shared oocytes from the same donor and showed discordant pregnancy outcome.
MATERIALS AND METHODS Study Design A matched case-control study was performed on 542 oocyte donation cycles that shared oocytes with discordant outcome, at
IVI-Madrid and Instituto Valenciano de Infertilidad from September 1999 until May 2001. Discordant outcome was established when at least one of the oocyte recipients from the same donor achieved pregnancy whereas the others did not. Recipients were divided into two groups: group 1 (278 cycles) who had a positive pregnancy outcome, and group 2 (264 cycles), who did not achieve pregnancy. Recipients from the pregnant group were 37.9 ⫾ 0.3 years old whereas recipients from the nonpregnant group were 38.2 ⫾ 0.3 years old. No Institutional Review Board approval was obtained as it was not required for this type of study.
Oocyte Donors All our donors volunteered altruistically, after being thoroughly informed, to donate their oocytes and fulfil the criteria to be admitted in our oocyte donation program. In short, they were 18 –35 years old, with complete medical history, which included current or past exposure to radiation or hazardous chemical substances, IV drug abuse, and past reproductive history. All had a normal physical and gynecological examination, no family history of hereditary or chromosomal diseases, normal karyotype, and negative screening for sexually transmitted diseases (STDs). They all received a long protocol of down-regulation with a GnRH-agonist (GnRH-a) (Decapeptyl 0.1 mg, Ipsen Pharma, Barcelona, Spain). Transvaginal ultrasound was performed to ascertain ovarian quiescence on the first 3 days of menses and then, controlled ovarian hyperstimulation was started as previously described (2). Briefly, they received 300 IU/day of urinary follicle-stimulating hormone (uFSH) for the first 3 days and then 150 IU/day until the mean leading follicles where ⬎18 mm in diameter. Human chorionic gonadotrophin (10,000 IU) was then administered and ovarian puncture was performed 36 hours afterward. Each anonymous donor was phenotypically matched with at least two potential recipients. Oocytes were evenly distributed according to their quality and maturity.
Oocyte Recipients Oocyte recipients entered our oocyte donation program due to one of the following diagnostic groups: premature ovarian failure/menopause (n ⫽ 235), failure to achieve pregnancy after at least four cycles of assisted reproduction techniques (ART) (n ⫽ 154), genetic or chromosomal disorders (n ⫽ 8), low response to controlled ovarian hyperstimulation (COH) (n ⫽ 111), recurrent miscarriage (n ⫽ 11), and other disorders (n ⫽ 23). Semen analysis was performed on each recipient’s husband and classified according to World Health Organization criteria (13). All oocyte recipients were taking hormone replacement therapy (HT), as previously described (14). Briefly, in patients with ovarian function, GnRH-a (Decapeptyl 3.75 mg) was administered in the midluteal phase of the previous cycle. The HT was started on the first day of the cycle with increasing doses of E2 valerate (Progynova, Schering Spain, FERTILITY & STERILITY威
Madrid, Spain), which was given as follows: 2 mg/day for the first 8 days of the cycle, followed by 4 mg/day for the next 3 days, and then 6 mg/day was continued until the oocyte donation was available or until the patient had vaginal spotting, in which case the cycle was canceled. On the 15th or 16th day since the beginning of HT, a transvaginal ultrasound was performed to measure endometrial thickness and serum E2 levels were obtained. When the oocyte donation was available the potential for normal fertilization was assessed by semen analysis or previously available fertilization data. Couples were offered the opportunity to undergo intracytoplasmic sperm injection (ICSI) if there was some evidence that low fertilization or fertilization failure could occur. Micronized P (800 mg/day, intravaginal) (Progeffik, Effik Laboratories, Madrid, Spain) was administered starting the day of oocyte donation, and embryo transfer was performed according to each patient’s program on day 2, 3, or 6 of embryo cleavage. Embryo transfer was performed on day 6 after embryo co-culture with epithelial endometrial cells as described elsewhere (15). On the second day of cleavage all embryos were classified according to the number of blastomeres and cytoplasmic fragmentation (grade 1: 0%, grade 2: ⱕ25%, grade 3: 26%– 50%, grade 4: 51%–75%, grade 5: ⬎75% of the embryo surface), as well as symmetry of blastomeres (grade 1: all blastomeres with similar size, grade 2: 75% of blastomeres symmetric, grade 3: ⬍50% with similar size) (16). Only good quality embryos were transferred (ⱖ4 blastomeres and ⬍25% of fragmentation with grade 1–2 of symmetry of blastomeres). Serum -hCG was measured the 14th day after the oocyte donation and 2 weeks later clinical pregnancy was confirmed by visualization of a gestational sac by means of a transvaginal ultrasound. Only patients with discordant outcome who shared oocytes from the same donor were included in this study.
Statistical Analysis When a pair of recipients with discordant outcome shared oocytes from a single donor, the pregnant recipient’s characteristics were compared with the nonpregnant recipient. If more than two oocyte recipients shared oocytes from a single donor, patients were matched with all the discordant ones from the same donor (Table 1). If, for example, one donor gave oocytes to four different patients, the following possibilities analyzed were: [1] one pregnant and three nonpregnant, thus three paired couples; [2] two pregnant and two nonpregnant, thus four paired couples; [3] three pregnant and one nonpregnant, thus three paired couples. Data were expressed as mean ⫾ SEM or percentages when appropriate. A value of P⬍.05 was considered significant. Statistical calculations were performed using Sigma Stat for Windows, version 2.0 (Jandel Scientific Corporation, San Rafael, CA). 55
TABLE 1 Matched pairs of egg recipients with discordant outcome. No. recipients/donor
Oocyte possibilities (matched from same donor) ⫽ n
2 3
1 pregnant/1 1 pregnant/2 2 pregnant/1 2 pregnant/2 3 pregnant/1 1 pregnant/3 4 pregnant/1 1 pregnant/4 3 pregnant/2 3 pregnant/3 6 pregnant/2 Total oocyte
4
5
6 8
nonpregnant (1 matched pair) ⫽ 94 nonpregnant (2 matched pairs) ⫽ 32 nonpregnant (2 matched pairs) ⫽ 43 nonpregnant (4 matched pairs) ⫽ 7 nonpregnant (3 matched pairs) ⫽ 7 nonpregnant (3 matched pairs) ⫽ 4 nonpregnant (4 matched pairs) ⫽ 2 nonpregnant (4 matched pairs) ⫽ 1 nonpregnant (6 matched pairs) ⫽ 2 nonpregnant (6 matched pairs) ⫽ 4 nonpregnant (12 matched pairs) ⫽ 1 donations ⫽ 197
No. matched pairs 94 ⫻ 1 ⫽ 94 32 ⫻ 2 ⫽ 64 43 ⫻ 2 ⫽ 86 7 ⫻ 4 ⫽ 28 7 ⫻ 3 ⫽ 21 4 ⫻ 3 ⫽ 12 2⫻4⫽8 1⫻4⫽4 2 ⫻ 6 ⫽ 12 4 ⫻ 6 ⫽ 24 1 ⫻ 12 ⫽ 12 Total matched pairs ⫽ 365
Garcia-Velasco. Discordant outcome in shared oocyte donation. Fertil Steril 2003.
Both pregnant and nonpregnant matched recipients were similar in terms of age (37.9 ⫾ 0.3 vs. 38.1 ⫾ 0.3 years), serum E2 levels (318.0 ⫾ 15.9 vs. 371.0 ⫾ 20.1 pg/mL), and endometrial thickness (9.2 ⫾ 0.1 vs. 9.2 ⫾ 0.1 mm). No differences were found in terms of the indications for the oocyte donation (Table 2).
nonpregnant group (P ⫽ not significant [NS]). Table 3 shows the distribution of semen anomalies, with no statistical differences between groups. In azoospermic men, spermatozoa from epididymal aspirate or testicular biopsy was used in a similar percentage in both groups (32% of the pregnant oocyte recipients and 33.3% of the nonpregnant recipients). In the remaining azoospermic men in whom no spermatozoa could be retrieved in the testicular biopsy, donor semen was used. Frozen semen samples were used in 89.7% of the pregnant group and in 84.6% of the nonpregnant group (P ⫽ NS). For further analysis, raw data on semen pathology before matching and pairing of egg recipients showed similar pregnancy rates (P ⫽ NS) among groups (data not shown).
Semen analysis from couples showed that it was pathological in 64.9% of the pregnant group and 61.4% in the
The mean number of oocytes received per patient was 7.9 ⫾ 0.1 in the pregnant group vs. 8.1 ⫾ 0.1 in the nonpregnant
RESULTS Oocytes from 197 oocyte donors where shared by 542 recipients, of which 278 conceived. We had a mean of 2.8 oocyte recipients per donor, therefore when there were more than 2 oocyte recipients per donor, each pregnant recipient was paired with each nonpregnant recipient, resulting in 365 matched-paired discordant outcome oocyte recipients (Table 1).
TABLE 2 General characteristics of matched-paired egg recipients. Pregnant oocyte recipients (n ⫽ 365) Age (y)a Serum E2 level (pg/mL)a Endometrial thickness (mm)a Indications for oocyte donationa Premature ovarian failure/menopause (%) Chromosomal/genetic diseases (%) Failure to conceive after ⱖ4 ART cycles (%) Low response (%) Repeated miscarriage (%) Others (%) a
37.9 ⫾ 0.3 318.0 ⫾ 15.9 9.2 ⫾ 0.1 163/365 (44.5) 5/365 (1.5) 106/365 (29.1) 64/365 (17.6) 8/365 (2.2) 19/365 (5.1)
Nonpregnant oocyte recipients (n ⫽ 365) 38.1 ⫾ 0.3 371.0 ⫾ 20.1 9.2 ⫾ 0.1 162/365 (44.3) 7/365 (1.9) 99/365 (27.2) 72/365 (19.7) 9/365 (2.5) 16/365 (4.4)
P is not significant.
Garcia-Velasco. Discordant outcome in shared oocyte donation. Fertil Steril 2003.
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Discordant outcome in shared oocyte donation
Vol. 80, No. 1, July 2003
TABLE 3 Male-associated factor of matched-paired egg recipients. Pregnant oocyte recipients (n ⫽ 365) Semen analysisa Normozoospermic (%) Asthenozoospermic Oligozoospermic Teratozoospermic Oligoteratozoospermic Oligoasthenozoospermic Astenoteratozoospermic Oligoasthenoteratozoospermic Azoospermia Epididymal aspirate/testicular biopsy Donor semen Frozen semen samplesa a
Nonpregnant oocyte recipients (n ⫽ 365)
128/365 (35.1) 120/365 (32.9) 5/365 (1.4) 2/365 (0.5) 0/365 (0) 50/365 (13.7) 10/365 (2.7) 25/365 (6.8) 25/365 (6.8) 8 (32.0)
141/365 (38.6) 95/365 (26.0) 12/365 (3.3) 2/365 (0.6) 2/365 (0.6) 69/365 (18.8) 16/365 (4.4) 16/365 (4.4) 12/365 (3.4) 4 (33.3)
17(68.0) 327/365 (89.7)
8 (66.6) 309/365 (84.6)
Embryo transfer was performed on day 2 of embryo cleavage in 61.7% of the pregnant group and in 63.0% of the nonpregnant group and in day 3 of cleavage in 21.6% and 27.9%, respectively (P ⫽ NS). A significantly higher number of day 6 embryo transfer was performed in the pregnant group when compared with the nonpregnant patients (16.6% vs. 9.0%, P⬍.05). Soft catheter for embryo replacement (Delphin, Gynetics, Hamont-Achel, Belgium) was used in 90.6% of embryo transfers in the pregnant group and in 89.9% of the nonpregnant group. A stiff catheter was used in 9.4% of the pregnant group and in 10.1% of the nonpregnant group; a catheter with a rigid outer sheath (Frydman, Gynetics) in 8.1% vs. 9.5% and a steel catheter was required in 1.3% vs. 0.6%, respectively (P ⫽ NS). Cervical tenaculum was required in only 0.7% of embryo transfers in the pregnant and in 0.6% of the nonpregnant group (P ⫽ NS).
DISCUSSION
P is not significant.
Garcia-Velasco. Discordant outcome in shared oocyte donation. Fertil Steril 2003.
group (P ⫽ NS). Fertilization was performed by conventional IVF or ICSI in 28.2% and 71.8% of the pregnant group and in 23.4% and 76.8% in the nonpregnant group, respectively (P ⫽ NS). Fertilization rate in ICSI couples was similar in both groups (83.6 ⫾ 0.8 vs. 82.1 ⫾ 0.9), as well as in IVF couples (78.6% vs. 76.1%). A similar number of good quality embryos were transferred in both groups of patients (2.8 ⫾ 0.03 vs. 2.7 ⫾ 0.03) (Table 4).
Oocyte recipients who share oocytes from a single donor and have discordant pregnancy outcome allows the assessment of several prognostic factors in the recipient that may be related to the different cycle outcome. Because at least one of the recipients conceived, oocytes have been proved to be good enough to achieve a clinical pregnancy, thus oocyte quality should be guaranteed. Four basic factors in oocyte recipients were studied: [1] demographic characteristics of oocyte recipients (age, indications for oocyte donation, serum E2 level, endometrial thickness), [2] male-associated factor, [3] oocyte donation cycle outcome, and [4] difficulty
TABLE 4 Cycle outcome and embryo transfer of matched-paired egg recipients.
No. oocytes received per couple ICSI couples ICSI fertilization rate IVF fertilization rate No. good quality embryos transferred Day of embryo transfer (%) 2 3 6 Embryo replacement catheter Soft (Delphin) Rigid: Frydman Metallic Tenaculum used at ET
Pregnant oocyte recipients (n ⫽ 365)
Nonpregnant oocyte recipients (n ⫽ 365)
P value
7.9 ⫾ 0.1 262/365 (71.8) 83.6% 78.6% 2.8 ⫾ 0.03
8.1 ⫾ 0.1 280/365 (76.8) 82.1% 76.1% 2.7 ⫾ 0.03
NS NS NS NS NS
225 (61.7) 79 (21.6) 61 (16.7)
230 (63.0) 102 (27.9) 33 (9.0)
331 (90.6) 34 (9.4) 8.1% 1.3% 3/365 (0.7)
328 (89.9) 37 (10.1) 9.5% 0.6% 2/365 (0.6)
NS NS .01 NS
NS
NS ⫽ not significant. Garcia-Velasco. Discordant outcome in shared oocyte donation. Fertil Steril 2003.
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of embryo transfer. None of these factors were found to be significantly related to pregnancy outcome. Conflicting reports on the influence of uterine age on pregnancy rate have been published (8 –11, 17). The different conclusions reached may be related to different study designs. On a previously randomized study from our group (9) we failed to show any relationship between the age of the recipient and pregnancy rate. Even after further analysis of different age subsets performed on our current series (data not shown), no differences were found between pregnant and nonpregnant recipients. Again, no differences were found according to whether ovarian function was present or absent, as previously described (17–19). Pregnancy outcome does not depend on the indication for oocyte donation, as equal distribution of the diagnostic groups was found between the two groups. Oocyte donation is an invaluable therapeutic option for a growing list of clinical indications, yielding excellent results (2). Serum E2 levels and endometrial thickness are markers routinely used to ascertain adequate endometrial preparation after exogenous HT. However, other retrospective studies (5, 7) showed that neither serum E2 level nor endometrial thickness was able to predict implantation in oocyte recipients. In the current study, we failed again to show a relationship between serum E2 levels or endometrial thickness with pregnancy outcome. We also analyzed different endometrial thickness and serum E2 levels subsets (data not shown). None of the recipients showed an endometrial thickness ⬍4 mm or serum E2 levels ⬍100 pg/mL, and we could not find any statistically significant differences among different subsets, confirming our previous study (5). Paternal influence in embryo development and cycle outcome continues to be debated. Two main mechanisms could be involved: [1] paternal transcriptional products after embryonic gene activation at the 4- to 8-cell stage (20) and [2] epigenetic factors, such as components transmitted by spermatozoa or the pattern of calcium signaling. A deleterious effect of the ICSI procedure itself seems unlikely, as it has been shown that bovine oocytes develop at the same rate to blastocyst stage after ICSI as compared with that of control oocytes (21). This has been confirmed with human oocytes in a prospective, randomized trial (22). Some investigators have claimed that ICSI cycles yield a lower percentage of blastocysts when compared to IVF cycles (23), suggesting a negative paternal effect on embryo development. However, sperm parameters do not seem to correlate with the outcome of ICSI treatment (24, 25). In fact, conventionally used semen parameters do not provide information about DNA quality in the sperm (26). In addition, fertilization rates and embryo morphology are similar in patients undergoing ICSI and IVF (27–29). In contrast to Nasseri et al. (12), we did not find any adverse effect with the use of ICSI, either with the use of 58
Garcia-Velasco et al.
fresh or frozen semen samples. These results are in agreement with a previous study in which no differences in pregnancy, implantation, or miscarriage rates were found between patients with oligoasthenozoospermia treated by ICSI and normozoospermic patients treated by conventional IVF in an oocyte donation program (30). Because our matched-paired data did not show significant differences in male factor, we also analyzed our raw data before matching and pairing, and could not find any statistically significant difference either, although this could be underpowered due to the small sample size in some groups. In addition, because the inclusion criteria for this study may not reflect the general oocyte recipient population, concerns about biased data could arise. However, male pathology was equally distributed on both pregnant and nonpregnant recipients. Still, we compared egg donation outcome between epididymal aspirate/testicular biopsy in the study group and our general oocyte recipient couples, during the study period. We performed 21 egg donations with epididymal aspirate/testicular biopsy, achieving 12 clinical pregnancies, which is similar to the pregnancy rate in this study (P ⫽ NS) and with our general egg donation program results (2). Therefore, even in the presence of severe male-associated factor there seems to be no deleterious effect in pregnancy rate, as it has been previously stated (30). Minor sperm deficiencies may be compensated with excellent oocyte quality, thus diminishing the impact of the male factor in the outcome. However, further studies are required to reach a firm conclusion in this regard. Approximately the same number of oocytes were assigned to each paired receptor and no differences were found in fertilization rates between groups, as expected in oocytes obtained from young and healthy volunteers. As part of an institutional policy, only good quality embryos are transferred in our oocyte donation program, otherwise embryo transfer is canceled. Conversely, no differences were found in embryo quality between groups. There were more blastocyst transfers in the pregnant group compared with the nonpregnant group (P⬍.05). However, this assertion should be taken cautiously as the study was not designed to demonstrate a difference in the day of embryo transfer and that these data are a retrospective analysis of clinical records. A previous study suggested that blastocyst transfer improves pregnancy rate in couples with implantation failure undergoing ovum donation, mostly due to a better embryo selection (15). Other investigators have suggested that blastocyst transfers in oocyte recipients are highly effective and can be used to decrease multiple pregnancy rates, as it allows better embryo selection while decreasing the number of embryos transferred (31, 32). A possible explanation for the higher pregnancies achieved with blastocyst transfer could be due to the better synchrony between embryo and endometrial development. Despite the fact that our findings may suggest that a higher
Discordant outcome in shared oocyte donation
Vol. 80, No. 1, July 2003
pregnancy rate can be achieved with blastocyst transfers compared to day 2 embryo transfer, only through prospective, randomized studies that compare early embryo transfer vs. blastocyst transfers will allow us to reach that conclusion. Two recently published studies of this type on IVF couples (33, 34) reached discordant conclusions, therefore this is still a matter of debate. A traumatic embryo transfer that requires the use of rigid catheters and cervical tenaculum has been found to negatively influence both implantation and pregnancy rates (35). A similar distribution in easy and difficult embryo transfers was observed in both groups of patients, thus we can rule out any bias in this regard. In addition to chance, other factors that explain the discordant pregnancy outcome in oocyte recipients sharing oocytes must be sought. There is some evidence that even young healthy women produce a high number of chromosomally abnormal embryos. In a retrospective case analysis of preimplantation genetic diagnosis performed on embryos from oocyte donors, a high number of chromosome aneuploidy was found (36). Both trisomies and monosomies were detected and could not be predicted on embryo morphology. Previous work by Munne´ et al. (37) has demonstrated that preimplantation genetic diagnosis may improve implantation rates by selecting chromosomally normal embryos. Thus, preimplantation genetic diagnosis on embryos from egg donors may further improve implantation and pregnancy rates. We can only speculate that more chromosomally abnormal embryos were present in egg recipients that did not achieve pregnancy compared with recipients who conceived. Further studies are needed to confirm this hypothesis and to verify whether these abnormalities are due to chromosomally abnormal oocytes or occur after syngamy; young, healthy egg donors with normal karyotype do not guarantee a normal conceptus. In conclusion, discordant pregnancy outcome in oocyte recipients sharing oocytes from single donors cannot be explained by recipient’s age, indication for oocyte donation, serum E2 level, or endometrial thickness. Male-associated factor did not seem to influence pregnancy outcome. Thus, commonly recorded recipient and cycle factors do not explain discordant cycle outcomes, which could be influenced by chance or some as yet untested factors. Future preimplantation genetic diagnosis studies may demonstrate whether chromosomally abnormal embryos can explain the discordant outcome in egg recipients. References 1. Kalfoglou AL, Glittelsohn J. A qualitative follow-up study of women’s experiences with oocyte donation. Hum Reprod 2000;15:798 –805. 2. Remohı´ J, Gartner B, Gallardo E, Yalil S, Simo´n C, Pellicer A. Pregnancy and birth rates after oocyte donation. Fertil Steril 1997;67: 717–23. 3. Stolwijk A, Zielhuis G, Sauer M, Hamilton CJ, Paulson RJ. The impact of the woman’s age on the success of standard and donor in vitro fertilization. Fertil Steril 1997;67:702–10.
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4. Meldrum D. Female reproductive aging-ovarian and uterine factors. Fertil Steril 1993;59:1–5. 5. Remohı´ J, Ardiles G, Garcı´a-Velasco J, Gaita´n P, Simo´n C, Pellicer A. Endometrial thickness and serum oestradiol concentrations as predictors of outcome in oocyte donation. Hum Reprod 1997;12:2271–6. 6. Check J, Nowrozzi K, Choe J, Dietterich C. Influence of endometrial thickness and echogenic patterns on pregnancy rate during in vitro fertilization. Fertil Steril 1991;56:1173–5. 7. Younis J, Simon A, Laufer N. Endometrial preparation: lessons from oocyte donation. Fertil Steril 1996;66:873–84. 8. Abdalla H, Wren M, 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. 9. Cano F, Simo´n C, Remohı´ J, Pellicer A. Effect of aging on the female reproductive system: evidence for a role of uterine sencescence in the decline in female fecundity. Fertil Steril 1995;64:584 –9. 10. Lydic ML, Liu JH, Rebar RW, Thomas MA, Cedars MI. Success of donor oocyte in vitro fertilization-embryo transfer in recipients with and without premature ovarian failure. Fertil Steril 1996;65:98 –102. 11. Noyes N, Hampton BS, Berkeley A, Licciardi F, Grifo J, Krey L. Factors useful in predicting the success of oocyte donation: a 3-year retrospective study. Fertil Steril 2001;76:92–7. 12. Nasseri A, Mukherjee T, Berkeley AS, Licciardi F, Krey LC, Copperman A. Predictors of discordant outcome in paired ovum recipients. Fertil Steril 2000;74(Suppl):S75. 13. World Health Organization. WHO laboratory manual for the examination of human sperm and sperm-cervical mucus interaction. Cambridge: Cambridge University Press, 1992. 14. Remohı´ J, Gutierrez A, Cano F, Ruiz A, Simo´n C, Pellicer A. Long estradiol replacement in an oocyte donation programme. Hum Reprod 1995;6:1387–91. 15. Simo´n C, Mercader A, Garcı´a-Velasco JA, Nikas G, Moreno C, Remohı´ J, et al. Coculture of human embryos with autologous human endometrial epithelial cells in patients with implantation failure. J Clin Endocrinol Metab 1999;84:2638 –46. 16. Conaghan J, Hardy K, Handyside AH, Winston R, Leese H. Selection criteria for human embryo transfer: a comparison of pyruvate uptake and morphology. J Assist Reprod Genet 1993;10:21–30. 17. Moomjy M, Mangieri R, Beltramone F, Cholst I, Veeck L, Rosenwaks Z. Shared oocyte donation: society’s benefits. Fertil Steril 2000;73: 1165–9. 18. Damario MA, Lesnick TG, Lessey BA, Kowalik A, Mandelin E, Seppala M, et al. Endometrial markers of uterine receptivity utilizing the donor oocyte model. Hum Reprod 2001;16:1893–9. 19. Remohı´ J, Gutierrez A, Vidal A, Tarı´n JJ, Pellicer A. The use of gonadotrophin-releasing hormone analogues in women receiving oocyte donation does not affect implantation rates. Hum Reprod 1994;9: 1761–4. 20. Braude P, Bolton V, Moore S. Human gene expression first occurs between the four and eight-cell stages of preimplantation development. Nature 1988;332:459 –61. 21. Motoishi M, Goto K, Tomita K, Ookutsu S, Nakanishi Y. Examination of the safety of intracytoplasmic injection procedures by using bovine zygotes. Hum Reprod 1996;11:618 –20. 22. Aboulghar MA, Mansour RT, Serour GI. Intracytoplasmic sperm injection in nonmale factor patients. In: Kempers RD, Cohen J, Haney AF, Younger JB, eds. Fertility and reproductive medicine. Amsterdam: Elsevier, 1998:475–81. 23. Shoukir Y, Chardonnens D, Campana A, Sakkas D. Blastocyst development from supernumerary embryos after intracytoplasmic sperm injection: a paternal influence? Hum Reprod 1998;13:1632–7. 24. Nagy Z, Liu J, Joris H, Verheyen G, Tournaye H, Camus M, et al. The result of intracytoplasmic sperm injection is not related to any of the three basic sperm parameters. Hum Reprod 1995;10:1123–9. 25. Palermo G, Joris H, Derde MP, Camus M, Devroey P, Van Steirteghem A. Sperm characteristics and outcome of human assisted fertilization by subzonal insemination and intracytoplasmic sperm injection. Fertil Steril 1993;59:826 –35. 26. Sakkas D, Urner F, Bizzaro D, Manicardi G, Bianchi PG, Shoukir Y, et al. Sperm nuclear DNA damage and altered chromatin structure: effect on fertilization and embryo development. Hum Reprod 1998;13(Suppl 4):11–9. 27. Bukulmez O, Yarali H, Yucel A, Sari T, Gurgan T. Intracytoplasmic sperm injection versus in vitro fertilization for patients with a tubal factor as their sole cause of infertility: a prospective, randomized trial. Fertil Steril 2000;73:38 –42. 28. Staessen C, Camus M, Clasen K, De Vos A, Van Steirteghem A. Conventional in-vitro fertilization versus intracytoplasmic sperm injec-
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29. 30.
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Discordant outcome in shared oocyte donation
Vol. 80, No. 1, July 2003