Endometrial volume and thickness measurements predict pituitary suppression and non-suppression during IVF

Background: The aim of this prospective study was to evaluate the usefulness of three-dimensional (3D) ultrasound measurement of endometrial volume and thickness as a predictor of pituitary suppression and nonsuppression following GnRH agonist administration for IVF. Methods: A total of 144 women undergoing 164 IVF cycles had transvaginal ultrasound measurement of their endometrial volume and thickness following 8-14 days of buserelin acetate administration. Serum estradiol concentrations were measured on the same day. Receiver operating characteristic (ROC) curve analysis was used for statistics. A ROC curve was produced for each of four estradiol thresholds commonly used by clinics to diagnose pituitary suppression (100, 150, 200, 250 pmol/l). From each curve, endometrial volume and thickness thresholds that best predicted pituitary suppression and, separately, non-suppression were selected and the associated sensitivity, specificity, positive and negative predictive values were reported. Results: The area under the curve (AUC) was consistently higher (better test) for 3D volume than thickness estimation for all four estradiol thresholds, although it was only significantly different when a threshold of 200 pmol/l was used. The AUC increased towards 1.0 (perfect test) for both volume and thickness measurement as the selected estradiol threshold increased. Very different volume and thickness thresholds were optimal depending on whether the aim of the test was to predict pituitary suppression or non-suppression. Conclusions: 3D endometrial volume estimation provides a new tool, alongside endometrial thickness measurement, to diagnose pituitary suppression and non-suppression during IVF. Different endometrial thresholds must be selected depending upon whether the priority is to identify pituitary suppressed, or arguably more importantly, nonsuppressed cycles.