A comparative study of GnRH antagonist and GnRH agonist in PCO patients undergoing IVF/ICSI cycles

Background: Polycystic ovarian syndrome (PCOS) patients are prone to premature LH surge and ovarian hyperstimulation syndrome (OHSS). Long GnRH analogue protocol and GnRH antagonist protocol are two methods utilized for induction ovulation in patients undergoing IVF/ICSI. Objective: The aim of this study was to compare the effects of GnRH agonists and antagonists in PCOS patients. Materials and Methods: A total of 60 PCOS patients under 35 years old were enrolled in this study. The patients have no history of thyroid disorder and hyperprolactinemia. All patients received OCP (LD) before starting the treatment. Then patients randomly divided into two groups. The agonist group underwent standard long GnRH analogue protocol. In antagonist group, HMG (150 IU/day) was started from third day of cycle. Then GnRH antagonist (0.25mg) was administered from 6 th day after HMG initiation (LH≤5 IU/ml) to the day of HCG injection. Follicular development monitored by vaginal ultra sonography and serum estradiol measurement. Results: There were no significant differences in age, duration of infertility, BMI, number of HMG ampules, number of follicles≥18mm, serum estradiol level on 6 th day of HMG initiation and HCG injection time, fertilization and pregnancy rate between two groups. However there were significant differences regarding duration of treatment, duration of HMG usage, LH level at the initiation of HMG, OHSS rate and number of Metaphase II oocytes between two groups (p<0.05). Conclusion: Usage of the GnRH antagonist may have more advantages such as the shorter duration of treatment and less gonadotrophin requirement. Furthermore, the incidence of OHSS can be reduced in GnRH antagonist comparing to agonist. For decreasing the risk of OHSS and abortion rate, we recommend long term use of OCP before starting the treatment.