Development of a multivariable prediction model for congenital unilateral absence of the vas deferens in male partners of infertile couples

Background Congenital unilateral absence of vas deferens has been diagnosed in fertile and normozoospermic males and is associated with the risk of unilateral renal absence or cystic fibrosis transmembrane conductance regulator mutations; but no prediction model currently exists to diagnose this condition. Objectives The study aims to identify clinical and biological variables that may have a predictive value for the diagnosis of congenital unilateral absence of vas deferens in male partners of infertile couples Materials and methods We designed a retrospective, cross-sectional, case-control study on electronic health records of a single tertiary-care andrological centre collected between 1998 and 2018. We included all subjects diagnosed with congenital unilateral absence of vas deferens using combined scrotal and transrectal ultrasounds. Controls were confirmed free of congenital unilateral absence of vas deferens by the same way. Both groups received standardised exploration procedures. Multivariable logistic regression model was built in a backward stepwise manner. Model performance and calibration were assessed. The study is reported according to TRIPOD statement. Results We included 69 congenital unilateral absence of vas deferens cases and 78 controls. Cases had a lower semen volume than controls. The congenital unilateral absence of vas deferens risk was associated with history of cryptorchidism and both levels of semen fructose and alpha-glucosidase. These predictors were confirmed by a random forest algorithm. The area under the curve was 0.886 (95% interval: 0.81-0.92). Calibration was performed with the Hosmer-Lemeshow test (p = 0.88). Discussion and conclusion History of cryptorchidism, semen fructose and alpha-glucosidase were identified as relevant and independent predictors for the diagnosis of congenital unilateral absence of vas deferens. The model enables to identify male patients with a high risk of congenital unilateral absence of vas deferens to whom a transrectal ultrasounds would be proposed to confirm the diagnosis, whatever their semen parameters. It will also help to address the risks of unilateral renal absence and of cystic fibrosis transmembrane conductance regulator mutations carrying during the management of infertile couples.