P-37

Materials and Methods: Mice (strain B6C3F1) were superovulated using a standard PMSG/hCG regimen. Embryos were cultured in Sage Fertilization media ⫹ 10% synthetic serum substitute (SSS, Irvine Scientific) in a low oxygen environment (5%02, 5%CO2 and 90%N2). Eight cell or compacted stage embryos (n⫽146) were divided into two groups and were either frozen rapidly, n⫽80, or slowly, n⫽ 66, using Quinn’s Advantage Embryo Freezing and Thaw kits (Sage IVF Inc.). Embryo freezing followed the short exposure regimen recommended by Sage: 1.5 M propanediol, (PrOH) (10 minutes), then 1.5M PrOH ⫹ 0.1M sucrose (5 minutes) at room temperature. Straws (IMV 0.25ml) were heat sealed and placed in a Biogenics Freeze Control CL5500 or CL8000 programmable freezer. Rapid freezing program: Start temperature ⫺6.5°C, manual seeding, hold for 1 minute, 0.90°C/ minute to ⫺30.0°C, plunge. Program duration, 25 minutes. Slow freezing program: Start temperature 20°C, 2°C/minute to ⫺6.5°C, manual seeding and hold for 10 minutes, 0.3°C/minute to ⫺35°C, plunge. Program duration, 105 minutes. Straws were held in liquid nitrogen overnight and thawed using a two step thaw: 0.5M sucrose (10 minutes) then 0.2M sucrose (10 minutes). Embryo survival (⬎ 50% of cells) was assessed at the time of thaw and via blastocyst formation. Results: Survival rates were 91% (73/80) for embryos frozen rapidly and 80% (53/66) for embryos frozen slowly. Rates of development to blastocyst were 89% (65/73) in the rapid freeze group and 85% (45/53) in the slow freeze group. These differences were not significant using Chi Square analysis. Conclusions: Survival of embryos using the rapid protocol was not significantly different from the standard slow protocol. Embryo development to blastocyst further indicated embryo competency. This may be related to decreased exposure time of embryos to potentially toxic cryoprotectants. There are advantages in the clinical lab setting to having better time management procedures, especially if success rates are not compromised. P-36 Extended Post-Thaw Culture Is an Efficient Way to Reduce the Number of Frozen Embryos in Storage. C. Khoury, J. Frederick, D.A. Potter, B. Behr. Objective: To compare the Pregnancy rate of frozen transfers over a period of 5 years, with thawed multi-cell (day 3) embryos or by keeping the thawed embryos in extended culture until the blastocyst stage prior to transfer. Also to compare the percentage of patients that are left with frozen embryos. Materials & Methods: We reviewed the records of 646 women who underwent a frozen embryo transfer during 2001-August 2005 at our Laguna Hills, California USA facility. Embryos were cultured in SAGE cleavage & Blast Media (Cooper Surgical, Trumbull, CT, USA) prior to transfer. Embryo transfers were performed in hormone replacement cycles. Patients received injections of estradiol valerate (4mg every third day) and daily injections of progesterone in oil, 100mg. All transfers were performed under standard conditions using ultrasound guidance. Clinical pregnancy rates & % of patients left with embryos were compared. Results:

year 2001 2002 2003 2004 ⴱ2005

Clinical # # % Pregnancy Cycles-FET Cycles-FBT Cycles-BT Rate 92 139 140 161 114

2 3 20 63 44

2% 2% 14% 39% 39%

33% 42% 44% 44% 43%

% Patients left with Frozen Embroys 36% 42% 37% 22% 26%

Note: FET-frozen embryo transfer, FBT-frozen blastocyst transfer, BTblastocyst transfer. ⴱJanuary-August of 2005 Conclusion: Over the five years period, we were able to maintain a good clinical pregnancy rate with both FET and FBT. However by culturing

S24

PCRS Abstracts

embryos to blastocyst the percentage of patients that had embryos left was significantly less. Frozen blastocyst transfer is an efficient and cost-effective (less cycles and no storage fee) for patients undergoing frozen embryo transfer.

P-37 Early Pregnancy Testosterone Levels in Miscarriages Compared to Ongoing Pregnancies. R.B. Lathi, C. Reddy, M.H. Dahan, A.A. Milki, J. Gebhardt, B. Behr, L.M. Westphal, Stanford University REI Center. Background: Women with polycystic ovarian syndrome have higher baseline testosterone levels and miscarriage rates, though the relationship between the two is not well understood. Testosterone is known to have an effect on endometrial cell growth and the immune system. High levels may impact implantation. Although studies have not shown a significant correlation between pre-pregnancy testosterone and pregnancy outcomes, testosterone levels during implantation and early pregnancy have not been carefully examined. Objective: To compare the level of total testosterone at 4-5 weeks gestation in ongoing pregnancies to spontaneous abortions. Materials and Methods: Serum samples from pregnant infertility patients between 4-5 weeks gestation were collected at the time of the initial ␤HCG determinations; in most patients, 2 separate samples were tested for total testosterone. Pre-pregnancy serum samples from the same patients were tested. Samples were analyzed using DPC Immulite 2500. Data is reported as mean ⫾ SD and analyzed using T-test. Results: 107 patients were studied, 26 of which were miscarriages, and 81 were singleton ongoing pregnancies. Four of the 26 women who miscarried had PCOS (15%) and 14 of the 81 with ongoing pregnancies had PCOS (17%). There were no significant differences in baseline testosterone or pregnancy testosterone levels between women who miscarried and women with ongoing singleton pregnancies. On average, the progesterone level in women who miscarried was lower than to those with ongoing pregnancies (see table). Karyotype of the conceptus was available in 16 miscarriages. Five had normal results and 11 had abnormal karyotypes. Comparing genetically normal and abnormal miscarriages, there was no difference in baseline testosterone (41 ⫾ 20 vs. 54 ⫾ 32 ng/dl, p⫽0.44) or pregnancy testosterone (118 ⫾ 70 vs. 90 ⫾47 ng/dl, p⫽0.2).

Miscarriages Ongoing pregnancies

N

Baseline testosterone

Pregnancy testosterone

Pregnancy progesterone

27 81

47 ⫾ 25 41 ⫾ 21 (p ⫽ 0.44)

88 ⫾ 54 94 ⫾ 66 (p ⫽ 0.58)

20 ⫾ 10 28 ⫾ 10 (p ⬍ 0.05)

Conclusions: Early pregnancy testosterone level does not predict miscarriage or have a clear association with miscarriage in our infertility population. Further studies are needed in the PCOS population to elucidate the mechanism of increased pregnancy loss.

P-38 Comparison of Letrozole to Gonadotropins (FSH) for Ovulation Induction in Clomiphene (CC) Failures. Y. Wen, R.B. Quintero, R. Urban, L.M. Westphal, R.B. Lathi, M.H. Dahan. Stanford University, Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology. Background: Letrozole, an aromatase inhibitor, has been demonstrated to induce ovulation in anovulatory patients who previously failed clomiphene citrate (CC). The traditional treatment for patients who fail to conceive with CC is gonadotropins. Given the risks and cost of gonadotropins, it is unclear whether gonadotropins are superior to letrozole after failing CC. Objective: To compare letrozole to gonadotropins as a treatment option for patients who failed to conceive with CC. Materials and Methods: Retrospective analysis of patients who failed CC and were subsequently treated with letrozole, 5 mg orally, from day 3 to 7 of the menstrual cycle or FSH starting on day 3 of the menstrual cycle. Both groups were treated with IUI. Patients failed CC if they did not conceive with at least 3 cycles or had an endometrial lining less than 6mm or

Vol. 85, Suppl 2, April 2006