OVULATION AFTER INTRAVENOUS AND INTRAMUSCULAR HUMAN CHORIONIC-GONADOTROPIN

Objective: To define the time interval from intravenous and intramuscu lar hCG administration to follicular wall rupture and the endocrinolog ic 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 rand om sequence with an intervening spontaneous menstrual cycle. Patients: Thirty women from the University of Vermont Reproductive Endocrinolog y Service with unexplained, male, or cervical factor infertility. Inte rventions: Subjects underwent superovulation with clomiphene citrate f ollowed by hCG administration when the lead follicle reached a mean di ameter of 18 mm. Follicular rupture was determined by ultrasound monit oring every 2 hours starting 31 and 30 hours after intravenous and int ramuscular hCG, respectively. Serum samples were obtained hourly for h ormone measurements. The study was completed 2 hours after follicular rupture or 48 hours after hCG administration. Results: Twenty-five sub jects received both intramuscular and intravenous hCG. The mean time t o ovulation was 40.4 hours after intramuscular hCG (range, less-than-o r-equal-to 36 to greater-than-or-equal-to 48 hours) and 38.3 hours aft er intravenous hCG (range, 33 to greater-than-or-equal-to 48 hours). N o differences were noted in the time interval to ovulation or rate of change in circulating E2 and P levels after IM versus IV hCG administr ation. 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 intramus cular hCG; and (3) the rate of change in circulating E2 and P levels a re not different after intravenous than intramuscular hCG.