OBJECTIVE: To investigate whether the variable length of the epididymides in men with congenital absence of the vas deferens might have a correlation with IVF and pregnancy rate results. DESIGN: Microsurgical retrieval of epididymal sperm from men with congenital absence of the vas deferens and their use for IVF. SETTING: Center for Reproductive Health, University of California, Irvine, California. PATIENTS: One hundred eight men with confirmed diagnosis of congenital absence of the vas deferens enrolled in the microsurgical epididymal sperm aspiration and IVF program. INTERVENTIONS: Measurement in centimeters of the epididymal length at the time of the sperm aspiration procedure. MAIN OUTCOME MEASURE: Rates of fertilization and pregnancy according to the epididymal 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 case, patients of group III had the highest fertilization and pregnancy rate (24% and 43%, respectively). Patients with the shortest epididymis (group I) had the worst IVF outcome (fertilization rate 7% and pregnancy rate 7%) whereas in group II the fertilization rate was 13% and the pregnancy rate was 18%. CONCLUSION: This study demonstrates that epididymal sperm from men with congenital absence of the vas deferens having 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 epididymal sperm.
OBJECTIVE: To investigate whether the variable length of the epididymides in men with congenital absence of the vas deferens might have a correlation with IVF and pregnancy rate results. DESIGN: Microsurgical retrieval of epididymal sperm from men with congenital absence of the vas deferens and their use for IVF. SETTING: Center for Reproductive Health, University of California, Irvine, California. PATIENTS: One hundred eight men with confirmed diagnosis of congenital absence of the vas deferens enrolled in the microsurgical epididymal sperm aspiration and IVF program. INTERVENTIONS: Measurement in centimeters of the epididymal length at the time of the sperm aspiration procedure. MAIN OUTCOME MEASURE: Rates of fertilization and pregnancy according to the epididymal 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 case, patients of group III had the highest fertilization and pregnancy rate (24% and 43%, respectively). Patients with the shortest epididymis (group I) had the worst IVF outcome (fertilization rate 7% and pregnancy rate 7%) whereas in group II the fertilization rate was 13% and the pregnancy rate was 18%. CONCLUSION: This study demonstrates that epididymal sperm from men with congenital absence of the vas deferens having 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 epididymal sperm.