"Internal coasting" for prevention of ovarian hyperstimulation syndrome (OHSS) in IVF/ICSI

Objectives: To prevent OHSS by interruption of the early stage of stimulation ("internal coasting"). Design: Prospective, randomized study Material and Methods: 139 women who had unsuccessfully undergone standard long protocol ICSI procedure, complicated by OHSS of moderate or severe degree. The women were randomized to two groups - 68 undergoing stimulation in which, after 2 days of 225 IU hMG there were 2 days without hMG, and then, for the remainder of the stimulation period, 150 IU hMG. The control group (71 women) received standard doses of hMG, as in the first ICSI cycle. The main outcome measures was the prevalence and severity of OHSS, implantation and pregnancy rates. Results: There were 39 cases of OHSS of moderate (32) and severe (7) degree in the control group and 7 (moderate) cases in the investigated group (p = 0.05). No differences were found in the implantation rate and pregnancy rate, the mean number of oocytes fertilized, fertilization rate and the mean number of embryos transferred. Conclusion: Stimulation with internal coasting is safe for women at a high risk of OHSS. It does not negatively influence fertilization, implantation or pregnancy rates.