P-29: Changes in measured endometrial thickness predict in vitro fertilization success

Abstract

Few studies have evaluated the change in endometrial thickness occurring during IVF stimulation. Based on the lack of available literature, this study was designed to assess the predictive ability of endometrial thickness and changes in endometrial thickness on pregnancy outcomes in patients undergoing in vitro fertilization. Retrospective cohort analysis. The patient population consisted of 132 infertility patients undergoing 132 fresh autologous IVF cycles. All patients received a transvaginal ultrasound to assess endometrial thickness at three defined points during IVF (1. at baseline after pituitary suppression before gonadotropin stimulation, 2. on the 6th day of gonadotropin stimulation, and 3. on the day of hCG administration). Primary outcome variables included endometrial lining thickness at baseline, on day 6 of gonadotropins, the day of hCG administration, and the change in endometrial thickness during gonadotropin stimulation. Patients attaining pregnancy had significantly greater endometrial thickness on day 6 (p < 0.001) and endometrial thickness on day of hCG administration (p < 0.05). Pregnant patients had a greater change in endometrial thickness from the baseline to day 6 (p < 0.05) when compared to non-pregnant patients. Threshold analysis and receiver-operator characteristic curves noted significant endometrial thickness levels for implantation and pregnancy rates. An endometrial thickness on day 6 of < 6 mm was found to have a significantly lower implantation rate (17.1% versus 33.3%) (p < 0.001, RR = 0.51 (0.34, 0.77)) and pregnancy rate (38.0% versus 64.5%) (p < 0.01, RR = 0.59 (0.40, 0.87)) than an endometrial thickness of ≥ 6 mm. A change in endometrial thickness from baseline to day 6 of < 3 mm was found to have a significantly lower implantation rate (22.4% versus 35.7%) (p < 0.01, RR = 0.63 (0.44, 0.88)) than a change in endometrial thickness of ≥ 3 mm. A change in endometrial thickness from baseline to day 6 of < 2 mm was found to have a significantly lower pregnancy rate (42.0% versus 62.7%) (p < 0.05, RR = 0.67 (0.46, 0.97)) compared to a change in endometrial thickness of ≥ 2 mm. Endometrial responsiveness and thickness during the early IVF stimulation seem to be better prognostic predictors of success than endometrial thickness at the start or the end of the IVF cycle. Increased endometrial responsiveness seen on day 6 of gonadotropin stimulation as compared to the baseline is important to IVF success. Endometrial thickness during the early part of the IVF cycle seems to be a more important prognostic variable than does endometrial thickness at the start or end of the IVF cycle.