Electrovasogram in patients with obstructive azoospermia and absent vas deferens.

The electric activity of the vas deferens (electrovasogram, EVG) was studied in 22 patients with obstructive azoospermia (OA), in 9 patients with bilaterally absent vasa deferentia, in 10 patients who had undergone epididymovasostomy for OA, and in 12 healthy volunteers (controls). Two electrodes were applied to the posterior aspect of the upper scrotum. EVG in normal subjects showed pacesetter potentials (PPs) that had the same frequency, amplitude, and velocity of conduction from both electrodes and were consistent in the individual subject on all test days. The PPs were followed randomly by action potentials (APs). The EVG in OA exhibited "bradyvasa," i.e., diminished PP frequency, amplitude, and velocity, in 14 patients and a silent EVG in 8. Eight of the ten patients in whom azoospermia persisted after epididymovasostomy had a silent EVG. The remaining two patients, whose semen character had normalized after epididymovasostomy, revealed a normal EVG. A "silent" EVG was recorded for the nine patients with absent vasa deferentia. The electric activity is believed to be responsible for vasal motility. The bradyvasa or silent EVG encountered in OA might be attributable to the arrested function of the vas deferens and resultant vasal inertia. The latter may persist after epididymovasostomy and be responsible for the failure of the semen to normalize, as occurred in eight patients. In conclusion, EVG is a simple, easy, noninvasive, and nonradiologic technique that might be used as a diagnostic tool in the investigation of vas deferens disorders and infertility.