Abstract
Introduction: “Coasting” is a method used in prevention of Ovarian Hyperstimulation Syndrome (OHSS) during In Vitro Fertilization (IVF) cycles. Coasting refers to witholding exogenous gonodotropine usage and delaying the administration of hCG in high risk cycles until serum estradiol levels falls into an acceptable range. The aim of our study is to evaluate coasting effect on IVF oucomes in patients with E2 levels of 4000-5000 pikogram.
Metod: This study was a single centered, retrospective and a case-control study. Study population were selected from women applied Zeynep Kamil Research Hospital IVF department between January 2003 and December 2013(n= 7850). Patients taking GnRH aganist or antagonist protocol, having BMI between 23-28 kg/m2, having E2 levels between 4000-5000 pikogram and age ≤43 were included in the study. Patients were divided in 2 groups as conrol group (Group 1, n=48) and coasted group (Group 2, n=34) according to whether or not coasting performed. Peak E2 levels before coasting, follicle count before oocyte pick up, collected M2 oocyte count, fertilized oocyte count, OHSS incidince and pregnancy incidence were compared between groups.Statistical analysis was performed using Student’s t test for continuous variables and chi-square test for categorical variables.
Results: While most of patients in group 2 needed less than 2 days of coasting, only two patient needed 4 days of coasting. E2 levels on the day of hCG in group 2 were significiantly lower than group 1 (4332.6±256.6 and 3180.8±702.9; p<0.0001, respectively). There were no statistically significiant difference in follicle count before oocyte pick up, collected M2 oocyte count, fertilized oocyte count, pregnancy rate and OHSS incidence in between groups.
Conclusion: Coasting is an effective method in high risk women to lower OHSS incidence. It can be appilied safely especially in patients having optimal follicular size and estradiol levels of 4000-5000.

Key words: Coasting, in-vitro fertilization, ovarian hyperstimulation syndrome