Follicule stimulating hormone (FSH) administer with trigger dose human chorionic gonadotropin (hCG) completely prevents ovarian hyperstimulation syndrome (OHSS). Randomised controlled study

Abstract

Complete prevention of OHSS has only being possible with avoidance of HCG trigger. Excessive administration of FSH to susceptible patients has being considered an attributing factor to OHSS. FSH peaks just before LH surge in the natural cycle without OHSS. This study examines a similar role for FSH in patients at risk of OHSS. 102 patients undergoing IVF/ICSI cycles at risk of OHSS with serum oestradiol (E2) = />3500 pg/ml, = />15 follicles in each ovary and 2 leading follicles of size = />18mm were prospectively randomised to two strategies groups (gp1&2) for the prevention of OHSS. All patients had received GnRH agonist long protocol and starting dose of 225 iu of HMG. The HMG was withheld in gp1(51 patients) until the E2 levels fell below 1500 pg/ml when trigger dose of HCG was administered. In the gp2 (51 patients) pure FSH was administered with the trigger dose of HCG irrespective of the E2 levels = />3500 pg/ml. The pure FSH dose was the equivalent in the last HMG dose. IVF or ICSI performed according to semen paramter. Three cleaved D3 or two D5 blastocyst embryos were transfered. OHSS was identified according the revised classification. Comparing gp1vsgp2 mean total dose of HMG (3322.5+/-1005vs3465+/-937.5), total number of follicles (38.5+/-3.1vs37.4 +/-4.2), serum E2 on the day of randomisation (4455.5+/-541.5vs4527,5 +/-682.5) were similar. Mean serum E2 on trigger day was significantly higher in gp2 (910+/-385.6vs4527.5+/-682, P<0.001) following mean duration of coasting (4.8+/ = 1.4 days) in gp1. Fertilisation, cleavage rates and mean quality of embryos was similar. Mean no oocytes (8.6+/-2.9vs26.4+/-3.5) and D5 blastocyst (3.5+/-1.2vs10.6+/-2.7) were significantly higher in gp2, P<0.001. Incidence of OHSS (10 moderate, 4 severe 1 critical) was signficantly higher in gp 1. No moderate, severe or critical OHSS in gp 2, P<0.001. Similar clinical pregnancy rates (48.6vs51.8%). Pure FSH blocks and completely prevents the initiation of OHSS by HCG trigger.