Prediction of successful outcome of microdissection testicular sperm extraction in men with idiopathic nonobstructive azoospermia

Purpose: Microsurgical techniques in testicular sperm extraction can improve sperm retrieval in patients with nonobstructive azoospermia (NOA). However, spermatozoa retrieval rates have still been reported to be around 50% for patients with NOA. Thus, a reliable prediction method for successful outcome is needed to avoid unnecessary surgery. In this retrospective study we determined the diagnostic and predictive values of noninvasive parameters used in the treatment of patients with NOA. Materials and Methods: We analyzed 9 preoperative factors including patient age, testicular volume and endocrinological data of 100 patients with NOA using multivariate logistic modeling. Testicular spermatozoa were retrieved successfully in 41 of the 100 patients (41%). Results: We found that the concentrations of follicle-stimulating hormone (FSH), total testosterone (TT) and inhibin B were considered the most influential preoperative factors. We developed a formula to calculate the probability of successful outcome, P = [1 + exp(5.201 - 0.048 x FSH - 0.449 x TT - 0.021 x inhibin B)](-1). Association of predicted probabilities and observed responses was 0.77. A predicted probability of more than 15.7% was found to be the best cutoff. Sensitivity was 71.0% and specificity was 71.4% as determined by receiver operating characteristic analysis. Conclusions: We concluded that our formula should be useful for doctors considering microdissection testicular sperm extraction for patients with NOA because our equation uses noninvasive parameters without a preoperative testicular biopsy, which is a relatively invasive examination.