Incidence of testicular microlithiasis after orchidopexy for cryptorchidism and its risk factors: A retrospective cohort study

Abstract

Introduction: Testicular microlithiasis (TML) is detected using scrotal ultrasound (US) and is characterized by hyperechoic non-shadowing foci 1-3 mm in diameter within the testicular parenchyma. Although a history of orchidopexy is a known risk factor for TML, and TML is a relatively common condition in postoperative cryptorchidism patients, no previous report has focused on risk factors for TML after orchidopexy.

Objective: The aims of this study were to evaluate the time-dependent incidence of TML after orchidopexy for cryptorchidism and to identify risk factors for TML.

Study design: This study included patients who underwent primary orchidopexy for cryptorchidism between 2004 and 2018 and could be evaluated using scrotal US before and after the procedure. Patients with chromosomal abnormalities and those with preoperative TML were excluded. The Kaplan-Meier method was used to assess postoperative TML appearance. The Cox proportional hazard model was used to evaluate three potential risk factors for postoperative TML: higher testicular position (proximal to the external inguinal ring), delayed orchidopexy (after 18 months of corrected age), and bilateral cryptorchidism.

Results: A total of 214 testes from 163 patients were eligible for inclusion (operative age and follow-up time: 2.2 years ± 18 months and 6.3 years ± 46 months, respectively). TML was found in 14/163 patients (8.6%) and 17/214 testes (8.1%). No testicular tumors were discovered during follow-up. The time-dependent TML incidence was 6.0% at 5 years and 11.2% at 10 years after surgery (Summary figure). A higher testicular location proximal to the external inguinal ring was found to be an independent risk factor in the Cox proportional hazard model (hazard ratio 6.18, 95% confidence interval 1.37-27.9, Summary figure).

Discussion: Our findings show that the incidence of postoperative TML increases for approximately 10 years following orchidopexy and is associated with a higher testicular location proximal to the external inguinal ring at surgery. In the adult population, TML with a history of cryptorchidism is a known risk factor of testicular malignancy. Given that more than 20% of boys with a higher testicular position developed TML, US evaluation to detect TML during pubety is feasible for the patients with a history of orchidopexy.

Conclusion: The incidence of postoperative TML in boys with cryptorchidism rises until puberty and is strongly associated with a higher testicular position at orchidopexy.

Keywords: Cryptorchidism; Long-term follow-up; Orchidopexy; Testicular microlithiasis; Testicular tumor.