Monitoring ovarian stimulation: Current perspectives

Abstract

In the normal ovulatory cycle, the recruited cohort of antral follicles can be identified by cycle day 5-7, the dominant follicle emerges by day 8-12, grows approximately 1-3 mm per day thereafter (most rapidly over the 1-2 days immediately preceding ovulation), and measures approximately 20-24 mm in mean diameter when the luteinizing hormone (LH) surge occurs; lesser follicles rarely exceed approximately 14 mm in diameter. In 5-10 % of spontaneous cycles, two preovulatory follicles may develop. The ultrasound examination enables the follicle diameter and endometrial thickness to be measured, which evaluates the fecundity function by using bloodflow assessment and the combined three dimensional (3D) and blood-flow investigation. Ovarian ultrasonography defines the size and number of follicles contributing to the measured estradiol (E2) level. Thus, in an ovulation induction cycle, ultrasound can tell us about the ovarian reserve and adequately monitor the process of downregulation, follicular and endometrial development, and timely administration of human chorionic hormone (hCG), with an increase in the overall pregnancy rates and decrease in the incidence of ovarian hyperstimulation syndrome (OHSS) and multiple pregnancy rate. Baseline follicular stimulating hormone (FSH), antiMullerian hormone (AMH), and inhibin B levels on day 2 or 3 on menstrual cycle and dynamic tests can give information about the ovarian reserve. Monitoring LH, E2, and progesterone during ovulation induction can determine the follicular growth and its competency, predict poor and hyper-response, and diagnose premature LH surge, premature luteinization and luteal phase adequacy.