stimulation type. Culture was extended past day 3 when possible to assist inembryo selection. Blastocyst formation rates were compared for the differ-ent standard IVF COH protocols. Down-regulation cycles (n�1942) werestimulated with luteal leuprolide acetate initiation followed by gonadotro-phins. Antagonist cycles (n�1037) were initiated on gonadotrophins, add-ing antagonists when the leading follicle was 14mm. Microflare cycles(n�302) were stimulated with a standard dilution of leuprolide acetate inearly follicular phase followed by gonadotrophins. Statistical analysis wasperformed by chi-square for categorical variables.

Results: The mean number of oocytes retrieved were 18.9� 8.8, 15.3�7.0 and 13.1� 5.2 for cycles of down-regulation, antagonists and microflarerespectively. There was a statistical difference in blastocyst formation rateand transfers done on Day 5 or 6 between down-regulation (42.6%),antagonist (32.9%) and microflare (17.5%) patients (p�.0001). Clinicalpregnancy rate when blastocysts were transferred was significantly higherfor the down-regulation group (73.8%), followed by antagonist (67.5%) andmicroflare patients (64.7%), (p�.003).

* p�.0001 * * p� .003

Conclusion: In a population of young and good responding patientsundergoing IVF, down-regulation protocols appear to induce a higherblastocyst formation rate compared to other stimulation protocols. Theincrease in blastocyst development rate can be partially attributed to a largeraverage number of oocytes retrieved per cycle in the down-regulationgroup, perhaps related to patient selection. Nevertheless, higher clinicalpregnancy rates in blastocyst transfers, when two embryos are replaced,suggest a stimulation dependent benefit. As expected, the microflare patientshad lower blastulation and pregnancy rates. This may not only result froma lower number of oocytes retrieved, but also as a result of differences inovarian reserve in patients requiring microflare protocol.

P-193

Comparison of different follicular diameters at initiation of GnRHantagonists in ART cycles. Alberto Kenny, Roberto Inza, Laura Londra,Eduardo Lombardi, Edgardo Young, Carlos Sueldo. IFER, Buenos Aires,Argentina.

Objective: Individualization when using GnRH antagonist (GnRH ant) inCOH optimized ART treatments (Ludwig, 2002). Today the most com-monly used criteria to initiate GnRH ant is the presence of a leading follicleat 14-15 mm in diameter. Our objective was to compare the reproductiveperformance in good prognosis IVF patients when the GnRH ant wasinitiated with the leading follicle size at 16-17 mm vs a control group wherethe GnRH ant was started when the leading follicle was at 14-15 mm indiameter.

Design: Comparative analysis of all good prognosis IVF cycles at ourcenter where the GnRH ant was used between June and December 2002.

Materials and Methods: A total of 107 good prognosis IVF patients thatwere �40 years of age and had a serum day 3 FSH �12mIU/ml wereevaluated. Group I (n�53), mean age 32.8 �3 y/o, was made of all patientswhere the GnRH ant was initiated with a leading follicle at 14-15 mm. Ingroup II (n�54), mean age 33 �3 y/o, the leading follicle was at 16-17 mmin diameter at GnRH ant initiation.

Ovarian stimulation was started on day 2-3 of the cycle with 300 IU dailyof rFSH during 5 days and then adjusted according to the ovarian response.GnRH ant at 0.25 mg sc daily was given according to study criteria. Whenthe leading follicle reached at least 18 mm in diameter, hCG 10000 IU wasadministered for oocyte retrieval. Embryo transfer was performed on day 2or 3 post- aspiration and the reproductive performance evaluated.

Results: In group I the mean estradiol level at GnRH ant initiation waslower than in group II (641 �366 vs 835 �706 pg/ml) but this difference

did not reach statistical significance. The mean estradiol level on hCG daywas similar between groups (1442 �985 vs 1357 �911, respectively). Themean number of oocytes retrieved (9.4 �5 vs 9 �5), fertilization rate(79.6% vs 82.2%), high grade embryo quality (74.5% vs 79.1%, Bolton,1989) and the number of embryos transferred per cycle (3 �1 vs 3.3 �1)were not different. Instead, the number GnRH ant doses in group I wassignificantly higher than in group II (3.6 �1.2 vs 3.2� 0.8, p�0.05). Theclinical pregnancy rate per cycle (46.9% vs 53.1%), implantation rate(20.6% vs 22.4%) and abortion rate (8.7% vs 3.8%) in groups I and IIrespectively were similar.

Conclusions: Our data shows that in good prognosis IVF patients thereproductive performance if GnRH ant is initiated when the leading follicleis at 16- 17 mm in diameter was as satisfactory as when the leading folliclewas at 14- 15 mm in size. This data may be useful for not cancelling the IVFcycle if the leading follicle is over the standard criteria (14-15 mm) beforeinitiating the GnRH ant.

P-194

Ganirelix can be used to restore normal expectation of pregnancy inpatients experiencing premature luteinization in Controlled OvarianHyperstimulation (COH) cycles for Intrauterine Insemination (IUI).Daniel Shapiro, Virginia Brown, Melinda Carter, William Roudebush.Reproductive Biology Assoc, Atlanta, GA.

Objective: To determine if prevention of premature luteinization with theGnRH antagonist Ganirelix (Antagon™, Organon, Inc., Rosewood, NJ)impacts cycle outcome in COH/IUI.

Design: Retrospective chart review.Materials and Methods: Seventy-nine cycles of COH/IUI were evaluated

for premature luteinization (PL; {a doubling of both the LH and Progester-one [P] values over baseline with absolute P levels greater than 1.5 ng/dl})on the day of hCG in rec-FSH stimulated IUI cycles. Rec-FSH treatment(Follistim™, Organon, Inc. Rosewood, NJ or Gonal-F™, Serono, Inc.Norwell, MA) was started on cycle day 2 or 3 and continued daily. Estradioland ultrasound monitoring were used to determine follicular development.hCG was administered in all cycles when 2-3 lead follicles of 1.8 cm wereseen by ultrasound. 17 patients experienced premature luteinization(PL) intheir first cycle of COH/IUI and were treated with a combination of rec-FSHand the GnRH antagonist Ganirelix in subsequent COH/IUI cycles. Antag-onist treatment was started on cycle day 6 or 7 of the subsequent COHcycles and continued until the morning of hCG injection. IUI was performedon consecutive days after hCG with the second IUI occuring 34-37 hoursafter hCG injection. Pregnancy was detected by serum testing. A patient wasconsidered pregnant if an on-going pregnancy was seen by ultrasound pastthe ninth menstrual week.

Results: Of the 79 cycles, 17 had PL detected. There were no ongoingpregnancies in these 17 cycles. Of the remaining 62 cycles, 9 pregnancieswere detected (15%). Twenty-seven cycles of COH/IUI were then per-formed with GnRH antagonist co-treatment in the 17 patients with earlyluteinization. Seven pregnancies were identified in this group (27%). Chi-square analysis revealed no difference in pregnancy rate between antagonisttreated cycles and COH cycles without PL. However, a highly significantdifference was found between cycles associated with early luteinization andcycles without PL or those treated with GnRH antagonist.

Conclusion: The use of the GnRH antagonist Ganirelix in patients withprevious COH cycle failure associated with premature luteinization go on tohave pregnancy rates in the range of expectation for cycles unaffected byearly lutieniztion. Patients with early luteinization in their cycles of COH/IUI have significantly lower pregnancy rates than patients unaffected by thisevent. The data seem to suggest that patients should be routinely tested forpremature luteinization in COH/IUI and can benefit from subsequent co-treatment with GnRH antagonist.

P-195

The relationship between follicular fluid hormone levels, embryo qual-ity and maternal age with in vitro fertilization after either the short orlong protocol using a GnRH agonist. Yasuhisa Araki. Institute forARMT, Gunma Setagun, Japan.

Objective: In recent years, older women have been presenting at a higherrate for assisted reproductive technology (ART). This study was designed to

S186 Abstracts Vol. 80, Suppl. 3, September 2003