Small-intestinal submucosa as an adhesion barrier in the rabbit

transfer cycles were thus achieved between 1/1/99 and 10/12/99. The control group consisted of patients whose cycles took place during calendar years 1997 and 1998. Similar protocols were used; however, all transfers were performed 72 hours after aspiration. All subjects underwent standard COH with leuprolide down-regulation followed by hMG or FSH stimulation. Embryos were cultured in 50 ␮L drops of media under oil, with P1 and blastocyst media used sequentially. Two blastocysts were transferred in 22 cases (88%), 3 in 2 cases, and 4 in one case. The clinical pregnancy rate was 18/25 (72%), the multiple gestation rate was 11/18 (61%), and the implantation (chorionic sac per embryo) rate was 30/54 (56%). Of the 18 clinical pregnancies, 7 (38.9%) were singletons and 8 (44.4%) were twins. There were 3 high-order multiple gestations, all associated with monozygotic twinning (3/18 [16.7%]; 95% CI 4 – 41%), a rate which is significantly higher than the established rate of 0.4% in the general population. Two of these had 2 blastocysts transferred, resulting in 2 sacs and 3 viable fetuses. The third patient had a known balanced chromosomal translocation and underwent transfer of 4 blastocysts, resulting in 3 chorionic sacs and 4 viable fetuses. There were 59 clinical pregnancies in the control group, with 7 high-order multiple gestations but only 1 monozygotic twin (1.7%; P⬍.05 vs. blastocyst transfer). We conclude that clinical blastocyst transfer 1) maintains good pregnancy rates in this group of patients and 2) is associated with a statistically significant increased rate of monozygotic twinning. PII S0015-0282(00) 00443-X O-14 Soy Phytoestrogens Decrease the Estrogenic Activity of Estradiol in an in vitro Bioassay Using a Human Endometrial Cell Line. M. J. Murray,1 B. A. Lessey.2 1University of California, Davis, Department of Obstetrics and Gynecology, Sacramento, CA; 2 University of North Carolina, Department of Obstetrics and Gynecology, Chapel Hill, NC. Introduction: Previously, soy phytoestrogens (SPEs) were considered to be merely weak estrogens because their binding affinity for the estrogen receptor (ER) was considerably less than that of estradiol. Currently, with our recent understanding of differences in ER␣ and ER␤, that view must be revised. Some phytoestrogens have a high affinity, relative to estradiol, for ER␤. The soy phytoestrogen genistein, for example, has a 20-fold greater affinity for the ER␤ relative to ER␣. Given the different tissue distribution of the ␣ and ␤ forms of ER, there is a cellular basis for tissue-selective effects of genistein. SPEs are considered natural selective estrogen receptor modulators (SERMs) because they are estrogen agonists for the brain, bone, and cardiovascular system while having antiestrogen effects on the breast and uterus. Recent data in menopausal nonhuman primates indicate that SPEs may oppose the proliferative effects of estradiol on the endometrium. Objective: In this study, we examine the potential for SPEs to oppose the estrogenic effects of estradiol in a human-derived endometrial epithelial cell line (Ishikawa cells). Methods: The effects of combining SPEs (genistein and daidzein), progesterone, or the pure estrogen receptor antagonist ICI 182,780 with estradiol were examined with an established in vitro bioassay of estrogenic action. Immunohistochemistry was also performed for the presence of ER and Ki67, a marker of cell proliferation. Results: The addition of SPEs to estradiol decreased the estrogenic activity of Ishikawa cells in a dose-dependent fashion. The statistically significant decrease observed with SPEs was greater than the addition of progesterone but less than that of ICI. Immunohistochemistry confirmed the presence of ER after incubation

FERTILITY & STERILITY威

with all combinations. The semi-quantitative score for Ki67 did not significantly change with the different treatment combinations. Conclusions: The addition of SPEs to estradiol decreases the estrogenic response in a human endometrial– derived cell line. In the endometrium, phytoestrogens may act as an ER antagonist and/or have a “progestin-like” effect opposing the action of estradiol. These findings strengthen the hypothesis that SPEs are naturally occurring SERMs and imply that the combination of estradiol and SPEs may be an alternative form of hormone replacement therapy. PII S0015-0282(00)00444-1 O-15 Less Frequent Progestin Administration in the Elderly Postmenopausal Woman on Hormonal Replacement Therapy (HRT). A. B. Pinto, E. F. Binder, W. M. Kohrt, D. B. Williams. Department of Ob/Gyn and Geriatrics/Gerontology, Washington University School of Medicine, St. Louis, MO. Objective: To determine the effect of less frequent progestin administration on the endometrium in elderly postmenopausal patients on HRT. Methods: Prospective, randomized, double-blind, placebo-controlled study. Postmenopausal women 75 years of age or older were randomized to take placebo or HRT with conjugated equine estrogens, 0.625 mg/d, plus medroxyprogesterone acetate, 5 mg/d, for 13 days every 3 months for 9 months. Transvaginal ultrasound (TVS) was performed at baseline and 9 months. Endometrial biopsy (EMB) was performed if the endometrial thickness was ⱖ5 mm or as clinically indicated. Patients in the HRT group are being followed observationally for a total of 18 months with TVS and EMB. Results: Of the 46 patients with an intact uterus recruited, 25 dropped out. Reasons for study dropout included medical reasons (42.3%), personal (46%), expired (4%), and refused testing (7%), with no differences between groups. Of the remaining 21 evaluable patients, there was no difference between groups with respect to age (HRT 80.6, placebo 81.8), past medical history or ethnicity. There was no significant difference in the endometrial thickness (mean ⫾ SEM) between groups at baseline (HRT 3.67 ⫾ 0.61 mm, placebo 5.22 ⫾ 9.19 mm; P⫽.17) and at 9 months (HRT 7.42 ⫾ 26.27 mm, placebo 5.22 ⫾ 9.19 mm; P⫽.24). One patient in each treatment arm complained of irregular bleeding. Of the 12 patients on HRT, 11 experienced scheduled bleeding every 3 months. At 9 months, 50% of patients on HRT showed evidence of proliferative endometrium compared with 11% in the placebo group (P⫽.18). There are currently 7 of 12 patients on HRT who have completed 18 months of follow-up. Following EMB, 6 patients were found to have atrophic endometrium; 1 of these patients demonstrated proliferative endometrium. Currently, no cases of endometrial hyperplasia or cancer have been detected. Conclusions: Less frequent progestin administration appears to be safe and well tolerated with regard to its effects on the endometrium in this small study and seems to be a reasonable treatment option in the elderly postmenopausal woman. PII S0015-0282(00) 00445-3 O-16 Small-Intestinal Submucosa as an Adhesion Barrier in the Rabbit. A. Z. Macon, P. E. Patton. Department of Obstetrics and Gynecology, Oregon Health Sciences University, Portland, OR. Objective: Adhesion formation is a significant cause of postoperative morbidity and mortality, including infertility, chronic pelvic pain, and bowel obstruction. Numerous materials for adhesion prevention have been investigated, but concerns of efficacy and ease of use have limited the widespread acceptance of any single

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agent. Small intestinal submucosa (SIS), derived from porcine origin, is currently marketed for general repair of soft tissue and tissue reconstruction. Preliminary studies have shown potential for decreased adhesion formation. The purpose of this investigation is to determine the efficacy of SIS in reducing adhesion formation when used as an adhesion barrier. Methods: We completed a prospective, randomized, controlled study involving 39 female New Zealand rabbits. A 2 ⫻ 2 cm peritoneal-muscular defect was created in the lateral pelvic sidewall bilaterally and both uterine horns were abraded until punctate bleeding occurred. Following randomization and by using a computer generated table, the barrier material was cut to cover the area of surgical injury, placed over the defect, and sutured with 6-0 ethibond. The remaining side served as a control. The uterine horns were then sutured to the superior margin of the ipsilateral defect. Six weeks later at necropsy, adhesions were graded on the basis of type, extent, and tenacity, and specimens of the graft site were obtained for histologic analysis. Results: All but 1 animal survived the postoperative period without complications. Ten of the rabbits were excluded from the data set since the uterine horns did not remain attached to the sidewall. The adhesions in the remaining 29 rabbits were graded by the same two investigators. The scores for type, extent and tenacity were summed and compared by using the Wilcoxon signed-rank test. Fewer postoperative adhesions were present at surgical sites covered by the SIS barrier (median ⫽ 4) compared to the control side (median⫽8, P⫽.01). Conclusions: Our results indicate that the use of a barrier composed of SIS results in a significant decrease in postoperative adhesion formation in the rabbit uterine horn sidewall model. Visually, the barrier appears to be incorporated into the sidewall peritoneum, and histologic analysis is currently in progress. The material is well tolerated, easy to handle, and shows promise as an adjuvant in postoperative adhesion prevention. PII S0015-0282 (00)00446-5

POSTER SESSIONS P-1 Improved Blastocyst Development by Combining Media From Two Different Commercial Vendors. L.N. Weckstein, A. Jacobson, D. Galen, K. Ivani, D. Walker, D. Kotze. Reproductive Science Center of the San Francisco Bay Area, San Ramon, CA. Objective: Low implantation rates and high multiple pregnancy rates have been the impetus for blastocyst embryo transfer. The availability of commercially developed sequential embryo culture media has facilitated the transition from day 3 to day 5 embryo transfers. After several groups reported excellent blastocyst development with these sequential media, we began using G1/G2 (period I, Scandinavian IVF Science). Conversion of embryos from day 3 cleaved to day 5 blastocyst was lower than expected. As a result, we switched to P1/Blastocyst (period II, Irvine Scientific). Blastocyst conversion improved; however, overall embryo cleavage and day 3 pregnancy rates declined. During period III embryos were cultured in G1 for the first 72 hours and then moved to Blastocyst Medium for extended culture. The purpose of this study was to compare conversion of day 3 cleaved embryos and pregnancy rates with extended culture in different growth media combinations. Design: Retrospective study. Materials and Methods: All IVF cycles during a 6-month period in our program were evaluated. Blastocyst conversion rates and pregnancy rates were calculated for three time periods during which different combinations of sequential media were used. Results: Findings are shown in the Table.

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PCRS Abstracts

Period I II III Period I II III

Media

No. ET

⫹ HCG

G1/G2 P1/Blast G1/Blast

118 22 107

45/118 (38%) 6/22 (27%) 50/107 (47%)

⫹HCG No. Blast ETs

Extended Culture Blast Conversion

6/10 (60%) 2/2 (100%) 19/32 (59%)

149/368 (40%) 13/22 (59%) 335/564 (59%)

The blastocyst conversion rate was significantly higher in period III than period I (P⬍.01). There was a trend toward a higher pregnancy rate in period III compared to period II (though period II N is small).

Conclusion: Highest blastocyst conversion and overall pregnancy rates were obtained using a combination of sequential media from two different commercial vendors. PII S0015-0282(00) 00447-7 P-2 Does Blastocyst Transfer Really Impact Clinical Outcome? G.S. Letterie, L. Marshall, M. Angle. Center for Fertility and Reproductive Endocrinology, Virginia Mason Medical Center, Seattle, WA. Objective: Multiple pregnancies after in vitro fertilization continue to pose a pressing clinical problem associated with increased perinatal morbidity and mortality. Reliable growth to the blastocyst stage may now be achieved in defined culture media, and the transfer of two blastocysts may provide a method to assure high pregnancy rates and minimize multiple rates. The purpose of the present study was to compare rates of clinical pregnancy, multiple pregnancies and spontaneous abortion in patients with embryos transferred on day 3 and blastocysts transferred on day 5. Design: Retrospective analysis of clinical outcomes. Setting: IVF clinic in a tertiary care center. Materials: Eighty-two completed cycles were studied. Embryos were evaluated daily for growth and morphology. Criteria for culture to the blastocyst stage included a minimum of 5 embryos on day 1 and at least 3 embryos at the 8 cell stage by day 3. If these were not met, cleavage stage embryos were transferred on day 3. Results: 51 cycles (62%) resulted in transfer of 2 blastocysts on day 5 and 31 (38%) in transfer of cleavage stage embryos on day 3. An average of 2.1 blastocysts and 3.3 cleavage stage embryos were transferred on day 5 and 3, respectively. There were no significant differences in any clinical parameter evaluated. Outcomes were as follows: for day 5 transfers, 71% overall pregnancy rate with 42% singleton, 31% twins, 6% triplets and 22% spontaneous abortion; for day 3 transfer, 52% clinical pregnancy rate, 38% singleton, 38% twins, 6% triplets and 18% spontaneous abortion. Of those cultured to blastocyst, 2 did not result in a transfer and 3 were transferred on day 6, with no pregnancies resulting. Conclusions: These data suggest that culture to blastocyst stage and transfer of blastocysts on day 5 offers no clinical advantage most notably in multiple pregnancies when compared to the transfer of 3 to 4 cleavage stage embryos on day 3. Transfer of one blastocyst may be a more effective technique for maintaining high pregnancy rates and reducing the multiple rate and deserves study. PII S0015-0282(00)00448-9 P-3 Selection Criteria for Identifying Embryos With a High Probability of Progressing to Blastocyst Formation, Pregnancy and Implantation. G.S. Letterie, L. Marshall, M. Angle. Center for

Vol. 73, No. 4, Suppl. 1, April 2000