Antral follicle count at down-regulation and prediction of poor ovarian response.

The aim of this study was to assess the accuracy of antral follicle count (AFC) performed after pituitary down-regulation (dAFC) in predicting poor ovarian response and the influence of using different thresholds of follicle size and count on its accuracy. Using three definitions of follicle size, three dAFC were determined for every patient in a consecutive cohort of 148 IVF cycles. The performance of the dAFC in predicting poor ovarian response (as expressed by area under the curve; AUC) for follicle size definitions of 2-5, 2-8, 2-10 mm, was not significantly different (AUC 0.80, 0.80, 0.79, respectively). Multilevel likelihood ratio for dAFC thresholds of <or=10, 11-15,16-20 and >20 were 5.43 (95% confidence interval 0.81-36.6), 3.06 (1.54-6.06), 1.63 (0.74-3.62) and 0.37 (0.19-0.75) with post-test probabilities of poor ovarian response of 50%, 36%, 23% and 6%, respectively, for a pretest probability of 15.5% for poor ovarian response. The single most important predictor of ovarian response was dAFC. The highest predictive performance was obtained in a model combining age and body mass index and dAFC (AUC = 0.82) showing only marginal improvement over dAFC alone. In conclusion, the performance of dAFC is the same regardless of the definition used for the size of antral follicles.