a Health Sciences University Regional Training and Research Hospital, Department of Urology, Erzurum, Turkey b Ataturk University Medical Faculty, Department of Urology, Erzurum, Turkey c Anesthesiology Clinical Research Office, Ataturk University Faculty of Medicine, Erzurum, Turkey * Correspondence to: Health Sciences University Regional Training and Research Hospital, Department of Urology, Palandoken, Erzurum, 25040, Turkey, Tel.: þ905376274158 emrecinisli@hotmail.com (A. E. Cinislioglu) drfatihm@gmail.com (F. Ozkaya) memsefaaltay@gmail.com (M.S. Altay) aksoyyilmaz@yahoo.com (Y. Aksoy) Keywords Undescended testicle; Epidi- dym; Anomaly Received 21 January 2020 Revised 3 September 2020 Accepted 7 September 2020 Available online xxx The incidence of epididymal anomalies in the bilateral and unilateral cryptorchidism cases: A comparative study Ahmet Emre Cinislioglu a, *, Fatih Ozkaya b,c , Mehmet Sefa Altay a , Yilmaz Aksoy b Summary Objective Our study was planned based on the hypothesis that epididymal anomalies may be more incidental and more severe in cases with bilateral undescended testicles compared to unilateral undescended cases. We also aimed to review the classifications of epididymal anomalies in the literature and to establish a simpler and clinically applicable classifi- cation in the present study. Materials and methods In this study, we retrospectively reviewed 197 pe- diatric patients who had been operated for unde- scended testis between January 2014 and January 2018. In the collective analysis of bilateral unde- scended testes cases, if the present anomaly were present in any testis, the anomaly was considered to be present for these cases and subjected to statis- tical analysis. Results The study included a total of 241 testicles of 197 patients. The incidence of epididymal anomalies was found to be significantly higher in cases with bilateral undescended testicles compared to uni- lateral cases (68.2%, 43.1%, respectively; p Z 0.003). It was observed that the incidence of epididymal anomaly and the severity of the anomaly statistically significantly decreased as the localiza- tion of the undescended testicle changed between the intraabdominal position and the external inguinal ring (p Z 0.0001). Discussion The effects of the undescended testicles on fertil- ization have been subject to evaluation in a limited number of studies and it has been reported that the rate of fertility is lower in patients with bilateral undescended testicles, whereas the fertility rate is close to that of healthy males in patients with uni- lateral undescended testicles. The incidence of epididymal anomalies was found to be higher in cases with bilateral undescended testicle, as shown in our study. However, based on these data, it is not possible to make a comment about whether this condition leads to infertility or not. Furthermore, accurate documentation of epididymal anomalies and standardization of the classifications of epidid- ymal anomalies may be guiding in the prevention of complications for the surgeons in the treatment of patients who will undergo orchiopexy. Conclusions We concluded that the incidence of epididymal anomalies was significantly higher in cases with bilateral undescended testicles compared to uni- lateral cases. In our study, based on a comprehen- sive high-quality surgical image archive, we believe that the differentiation of epididymal anomalies according to the classification we have proposed will make it possible to create a database that is easier to use clinically in a more objective way. + MODEL Please cite this article as: Cinislioglu AE et al., The incidence of epididymal anomalies in the bilateral and unilateral cryptorchidism cases: A comparative study, Journal of Pediatric Urology, https://doi.org/10.1016/j.jpurol.2020.09.002 https://doi.org/10.1016/j.jpurol.2020.09.002 1477-5131/ª 2020 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved. Journal of Pediatric Urology (xxxx) xxx xxx