NOA masquerading as OA: Rethinking the role of testis biopsy from an East Asian perspective

Background: In this study, we aimed to evaluate the proportion of non-obstructive azoospermia (NOA) cases exhibiting features resembling the obstructive azoospermia (OA) phenotype and assess the applicability of the Schoor criteria in an East Asian cohort. Methods: We retrospectively reviewed azoospermic patients who presented with low follicle-stimulating hormone level (≤ 9.2 IU/L) and large testicular volume (≥ 15 mL), consistent with the “phenotypical OA (phOA)” criteria proposed by Huang et al. (2018). All patients underwent testicular biopsy to confirm the pathological diagnosis. Complete spermatogenesis was considered the key feature of “pathological OA (pOA).” Results: A total of 271 patients with azoospermia were included in the analysis. Among them, 222 (81.9%) exhibited complete spermatogenesis consistent with pOA, whereas 49 (18.1%) were diagnosed with pathological NOA (pNOA). According to the Schoor criteria, 17 patients were classified as phOA; however, two (11.8%) were subsequently confirmed to have pNOA. Conversely, 31 patients were classified as having phNOA, of whom 23 (74.2%) demonstrated pOA on testicular biopsy. Under the Schoor criteria, the positive predictive value (PPV) for pOA was 88.2%, and the negative predictive value (NPV) for pOA was 25.8%. Using the Huang criteria, 49 of 271 patients (18.1%) met the definition of phOA but were diagnosed as pNOA on biopsy (i.e., false positives), yielding a PPV of 81.9% for pOA. Conclusion: The Schoor criteria, derived from a Caucasian cohort, may be unsuitable for East Asian patients, given the much lower NPVs for pOA in our cohort (25.8%) than that in the Schoor study (92.3%). These findings highlight the limitations of relying solely on clinical criteria, either Schoor or Huang, to guide sperm retrieval strategies, including the choice of retrieval method and microsurgical approach. Therefore, a testicular biopsy is essential to confirm complete spermatogenesis in patients with clinically phOA.