A comparison of the relative efficiency of ICSI and extended culture with epididymal sperm versus testicular sperm in patients with obstructive azoospermia

This is a retrospective cohort study comparing blastocyst transfer outcomes following intracytoplasmic sperm injection utilizing epididymal versus testicular sperm for men with obstructive azoospermia. All cases at a single center between 2012 and 2016 were included. Operative approach was selected at the surgeon's discretion and included microepididymal sperm aspiration or testicular sperm extraction. Blastocyst culture was exclusively utilized prior to transfer. The primary outcome was live birth rate. Secondary outcomes included fertilization rate, blastulation rate, euploidy rate, and implantation rate. A mixed effects model was performed. Seventy-six microepididymal sperm aspiration cases and 93 testicular sperm extraction cases were analyzed. The live birth rate was equivalent (48.6% vs 50.5%, P = 0.77). However, on mixed effects model, epididymal sperm resulted in a greater likelihood of fertilization (adjusted OR: 1.37, 95% CI: 1.05-1.81, P = 0.02) and produced a higher blastulation rate (adjusted OR: 1.41, 95% CI: 1.1-1.85, P = 0.01). As a result, the epididymal sperm group had more supernumerary blastocysts available (4.3 vs 3, P < 0.05). The euploidy rate was no different. Pregnancy rates were no different through the first transfer cycle. However, intracytoplasmic sperm injection following microepididymal sperm aspiration resulted in a greater number of usable blastocysts per patient. Thus, the true benefit of epididymal sperm may only be demonstrated via a comparison of cumulative pregnancy rates after multiple transfers from one cohort.