Sites of residual spermatozoa after irrigation of the distal vas deferens using normal saline solution during vasectomy in a rat model.

We have previously reported that irrigation of the distal vas deferens using a normal saline solution (NSS) is successful in removing a large amount of spermatozoa from the tract. However, this technique does not completely remove all the motile spermatozoa from the ejaculate. The aim of the present study is to evaluate the location of the residual spermatozoa after distally irrigating the vas deferens. Twenty male Sprague-Dawley rats (400-450 g) constitute our study population. The animals were divided into two groups: group 1, control group (n = 10), rats that undergo only vasectomy and group 2, experimented group (n = 10), rats that undergo vasectomy and distal irrigation of the vas deferens using 3 mL of NSS. In both groups, the middle and terminal parts of the vas deferens including the seminal vesicles are removed and sent for spermatozoa count. The post-vasectomy urine samples containing spermatozoa are obtained by mid-ventral cystocentesis and the concentration is determined using a haemocytometer. More spermatozoa was found in the urine samples of the experimented group than the control (21.3 +/- 10.61 vs. 0.2 +/- 0.20 million/ml, p-value = 0.068), and lesser residual sperms reside at both the middle and the terminal parts of the vas deferens (0.5 +/- 0.31 vs. 3.0 +/- 0.00; p = 0.008 and 1.1 +/- 0.99 vs. 2.0 +/- 0.00; p = 0.036 respectively). No sperms were present in the seminal vesicles of the control group, but two of 10 rats in the experimented group had few to moderate amount of sperms in their seminal vesicles (p = 0.180). After the distal irrigation of the vas deferens using NSS, some residual sperms resided in the middle and more at the distal part of the vas with a few that escaped into the seminal vesicles.