Development and initial evaluation of a vas deferens valve.

In 17 cases of vasectomy, the external diameter of vas deferens was found to be 2.07 +/- .27 mm (Mean +/- S.D.) with a range from 1.7 to 2.8 mm. The internal diameters were 0.93 +/- 0.13 at 5 g and 1.24 +/- 0.16 mm at 100 g insertion force applied to the measuring cone, with lumen ranges from 0.7 to 1.2 and 1.0 to 1.7 mm, respectively. The left-right variations in the same inidividual were of a similar order as between different individuals. Measurements in 6-10 kg rhesus monkeys revealed an internal vas diameter around 0.6 mm with the measuring cone only eased in. At considerably high pressure the vas could be distended to show an internal diameter around 1 mm. The external diameters ranged from 1.5 to 2 mm. Local application to the vas in vivo or in vitro of alpha or beta adrenergic blocking agents, and sodium nitrate had no appreciable effects on the diameters. Three types of valves were developed and tested. The tap-like and the rotary valves were not satisfactorily leak-proof. But the valve with stop-cock mechanism was found to be satisfactory. It was further tested by examining the ejaculate obtained by the method of electro-ejaculation after implanting the valve in the monkey vas. The stop-cock valve is being proposed as a working model for producing reversible vas-occlusion.