Human chorionic gonadotropin for in vitro oocyte maturation: does it improve the endometrium or implantation?

To determine the effect of human chorionic gonadotropin (hCG) priming on endometrial receptivity in women with polycystic ovary syndrome undergoing in vitro maturation.

The study was a randomized, controlled trial. After a withdrawal bleed, on day 8-10 of the cycle, women were randomized to receive 10,000 IU hCG or none 36 hours before immature oocyte retrieval. Oocytes were matured and fertilized, and up to 3 embryos were transferred. Prior to transfer, endometrial thickness, uterine artery pulsatility index and subendometrial bloodflow were determined.

There was no difference in endometrial thickness (10.1 vs. 10.4 mm), uterine artery pulsatility index (2.45 vs. 2.65) or absent subendometrial bloodflow (23% vs. 18%) between the treatment and control groups. Higher numbers of embryos were produced in the treatment group (7.0 vs. 3.6), resulting in more pregnancies, although the implantation rates (16.7 vs. 16.0%) were similar.

Preretrieval hCG priming does not improve the ultrasound parameters of endometrial receptivity or the implantation rate, although more embryos are generated.