Testicular regression syndrome in children: a retrospective analysis of diagnostic and laparoscopic findings.

Purpose: Testicular regression syndrome (TRS) is a cause of nonpalpable testis resulting from prenatal testicular involution. This study aims to describe clinical, ultrasonographic, and laparoscopic characteristics and surgical management of TRS, and to evaluate the necessity of inguinal exploration following laparoscopy. Materials and methods: A retrospective descriptive study was conducted on boys <16 years who underwent laparoscopic exploration for unilateral intra-abdominal nonpalpable testes at Vietnam National Children's Hospital between January 2021 and October 2025 and were diagnosed intraoperatively with TRS. Data collected included age, laterality, ultrasonographic findings, laparoscopic features, the decision to perform inguinal exploration, and histopathology of nubbin. Contralateral testicular size was measured by ultrasonography and compared with age-matched normal values, with Results: Forty-three patients were included; median age at surgery was 26 months (range 9-156 months), and 32 cases (74.4%) involved the left side. Ultrasonography yielded false-positive findings in 12 cases (27.9%). Contralateral testicular volume was larger than normal in children <24 months (0.86 ± 0.23 vs. 0.44 ± 0.14 mL; Conclusions: Testicular regression syndrome (TRS) is characterized by left-sided predominance and age-dependent compensatory hypertrophy of the contralateral testis. Ultrasonography is unreliable for diagnosis. While inguinal exploration frequently identifies fibrous remnants containing histological markers of regression, the clinical necessity of routine excision remains debated. We advocate for an individualized management approach that balances the benefits of definitive diagnosis against the low risk of malignancy.