Difficulties in differential diagnosis between obstructive and non-obstructive azoospermia

Introduction. The difference between obstructive and non-obstructive azoospermia (OA and NOA) is important for the choice of treatment tactics and adequate counseling of a married couple.Objective. To describe, analyze, and classify possible challenges in differentiating between two types of azoospermiaMaterials and methods. The retrospective review of database on surgical sperm retrieval attempts performed our hospital (n = 754). A subpopulation of 216 patients who were preliminary diagnosed with OA, was selected for further analysis. All patients had testicular pathology data following sperm retrieval attempt. Rate of reclassification was assessed as a primary outcome. Reclassified cases were further analyzed to find a possible reason for incorrect differential diagnosis.Results. Among 216 patients with initially suspected OA, 131 (60.6%) had evidence of spermatogenic dysfunction on pathological examination of seminiferous tubules. Multivariate regression analysis showed that only regular exposure to high temperatures was an independent predictor of NOA detection in patients with normal endocrine and clinical parameters (OR = 1.989; 95% CI = 1.101 – 3.595). Analysis of the decision tree showed that patients with inhibin B levels below 93 pg/ml had the highest risk of an incorrect initial diagnosis (82.6%).Conclusions. Differential diagnosis of OA and NOA is not such a simple task. Any case of azoospermia against the background of normal semen volume by default should be considered as a case of NOA if there is no anamnestic or clinical data clearly indicating obstruction. Regular exposure to high temperature is likely to cause azoospermia in men with initially severe disorders of spermatogenesis. Finally, the reference values of inhibin B offered by most laboratories are not intended to assess reproductive function.