Ovulation after intravenous and intramuscular human chorionic gonadotropin

Abstract

Objective: To define the time interval from intravenous and intramuscular hCG administration to follicular wall rupture and the endocrinologic events associated with ovulation.

Design: Subjects were studied in two cycles and received hCG either 10,000 IU IM or 500 IU IV in a random sequence with an intervening spontaneous menstrual cycle.

Patients: Thirty women from the University of Vermont Reproductive Endocrinology Service with unexplained, male, or cervical factor infertility.

Interventions: Subjects underwent superovulation with clomiphene citrate followed by hCG administration when the lead follicle reached a mean diameter of 18 mm. Follicular rupture was determined by ultrasound monitoring every 2 hours starting 31 and 30 hours after intravenous and intramuscular hCG, respectively. Serum samples were obtained hourly for hormone measurements. The study was completed 2 hours after follicular rupture or 48 hours after hCG administration.

Results: Twenty-five subjects received both intramuscular and intravenous hCG. The mean time to ovulation was 40.4 hours after intramuscular hCG (range, < or = 36 to > or = 48 hours) and 38.3 hours after intravenous hCG (range, 33 to > or = 48 hours). No differences were noted in the time interval to ovulation or rate of change in circulating E2 and P levels after IM versus IV hCG administration.

Conclusions: These findings suggest (1) ovulation occurs over a broad range of time after hCG administration; (2) ovulation does not occur in a more specific time interval after intravenous than intramuscular hCG; and (3) the rate of change in circulating E2 and P levels are not different after intravenous than intramuscular hCG.