Korean J Fertil Steril.  1999 Aug;26(2):163-170.

GnRH Agonist Stimulation Test (GAST) for Prediction of Ovarian Response in Controlled Ovarian Stimulation (COH)

• Kim MR
• Song IO
• Yeon HJ
• Choi BC
• Paik EC
• Koong MK
• Son IP
• Lee JW
• Kang IS

Abstract

OBJECTIVES
The aims of this study are 1) to determine if GAST is a better indicator in predicting ovarian response to COH compared with patient's age or basal FSH level and 2) to evaluate its role in detecting abnormal ovarian response. DESIGN : Prospective study in 118 patients undergoing IVF-ET using GnRH-a short protocol during May-September 1995.
MATERIALS AND METHODS
After blood sampling for basal FSH and estradiol (E2) on cycle day two, 0.5 ml (0.525 mg) GnRH agonist (Suprefact, Hoechst) was injected subcutaneously. Serum E2 was measured 24 hours later. Initial E2 difference (deltaE2) was defined as the change in E2 on day 3 over the baseline day 2 value. Sixteen patients with ovarian cyst or single ovary or incorrect blood collection time were excluded from the analysis. The patients were divided into three groups by deltaE2; group A (n=30):deltaE2<40 pg/ml, group B (n=52): 40 pg/ml< or =deltaE2<100 pg/ml, group C (n=20): deltaE2< or =100 pg/ml. COH was done by GnRH agonist/HMG/hCG and IVF-EF was followed. Ratio of E2 on day of hCG injection over the number of ampules of gonadotropins used (E2hCGday/Amp) was regarded as ovarian responsiveness. Poor ovarian response and overstimulation were defined as E2 hCGday less than 600 pg/ml and greater than 5000 pg/ml, respectively.
RESULTS
Mean age (+/-SEM) in group A, B and C were 33.7+/-0.8*, 31.5 +/-0.6 and 30.6+/-0.5*, respectively (*: p<0.05). Mean basal FSH level of group A (11.1+/-1.1 mIU/ml) was significantly higher than those of B (7.4+/- 0.2 mIU/ml) and C (6.8+/-0.4 mIU/ml) 0<0.001). Mean E2hCGday of group A was significantly lower than those of group B or C, i.e., 1402.1+/-187.7 pg/ml, 3153.2+/- 240.0 pg/ml, 4078.8+/-306.4 pg/ml respectively (p<0.0001). The number of ampules of gonadotropins used in group A was significantly greater than those in group B or C: 38.6+/-2.3, 24.2+/-1.1 and 18.5+/-1.0 (p<0.0001). The number of oocytes retrieved in group A was significantly smaller than those in group B or C: 6.4+/-1.1, 15.5+/-1.1 and 18.6+/-1.6, respectively (p<0.0001). By stepwise multiple regression, only deltaE2 showed a significant correlation (r=0.68, p<0.0001) with E2HCGday/Amp, while age or basal FSH level were not significant. Likewise, only deltaE2 correlated significantly with the number of oocytes retrieved (r=0.57, p<0.001). All four patients whose COH was canceled due to poor ovarian response belonged to group A only (Fisher's exact test, p<0.01). Whereas none of 30 patients in group A (0%) had overstimulation, 14 patients among 72 patients (19.4%) in group B and C had overstimulation (Fisher's exact test, p<0.01).
CONCLUSIONS
These data suggest that initial E2 difference after GAST may be a better prognostic indicator of ovarian response to COH than age or basal FSH level. Since initial E2 difference demonstrates significant association with abnormal ovarian response such as poor ovarian response necessitating cycle cancellation or overstimulation, GAST may be helpful in monitoring and consultation of patients during COH in IVF-ET cycle.

MeSH Terms

Estradiol
Female
Gonadotropin-Releasing Hormone*
Gonadotropins
Humans
Oocytes
Ovarian Cysts
Ovary
Ovulation Induction*
Prospective Studies
Estradiol
Gonadotropin-Releasing Hormone
Gonadotropins