CORRELATION BETWEEN EPIDIDYMAL LENGTH AND FERTILIZATION RATE IN MEN WITH CONGENITAL ABSENCE OF THE VAS-DEFERENS

Objective: To investigate whether the variable length of the epididymi des in men with congenital absence of the vas deferens might have a co rrelation with IVF and pregnancy rate results. Design: Microsurgical r etrieval of epididymal sperm from men with congenital absence of the v as deferens and their use for IVF. Setting: Center for Reproductive He alth, University of California, Irvine, California. Patients: One hund red eight men with confirmed diagnosis of congenital absence of the va s deferens enrolled in the microsurgical epididymal sperm aspiration a nd IVF program. Interventions: Measurement in centimeters of the epidi dymal length at the time of the sperm aspiration procedure. Main Outco me Measure: Rates of fertilization and pregnancy according to the epid idymal length. Results: Three groups were identified: group I (n = 29) , epididymal length between 0.5 and 1.9 cm; group II (n = 66), length between 2.0 and 4.0 cm; and,group III (n = 13), length in excess of 4. 0 cm. Although the aspiration site was the proximal caput for each cas e, patients of group III had the highest fertilization and pregnancy r ate (24% and 43%, respectively). Patients with the shortest epididymis (group I) had the worst IVF outcome (fertilization rate 7% and pregna ncy rate 7%) whereas in group II the fertilization rate was 13% and th e pregnancy rate was 18%. Conclusion: This study demonstrates that epi didymal sperm from men with congenital absence of the vas deferens hav ing a longer epididymis have a better IVF rate. A long epididymis can allow [1] the arrival of more frequent waves of fresh sperm whereas in a short epididymis the system is completely congested and occupied by old and senescent sperm, [2] less obstructive damages, and [3] a back flow of biochemical factors produced in the more distal segments that could ultimately enhance the fertilization capacity of proximal epidi dymal sperm.