Venogenic dysfunction is often suspected during evaluation by the finding of a sub-optimal erectile response to intracavernosal injection despite a normal arterial response on duplex Doppler sonography. The presence of persistent end-diastolic flow of greater than 5 cm/sec on duplex sonography has also been shown in some studies to correlate with the finding of venous leakage (118, 119). The gold standard test for the diagnosis of venogenic erectile dysfunction remains the dynamic infusion cavernosometry and cavernosography (DICC). Cavernosometry and cavernosography can be used to document the severity of venous leakage as well as visualize the sites of leakage (120-123). An abnormal cavernosometry (after injection of vasodilators to completely relax the penile smooth muscles) is 1) an intracavernosal infusion rate of greater than 10cc/minute of saline to maintain the erection or 2) a drop of intracavernosal pressure of greater than 50 mmHg within 30 seconds of terminating the saline infusion (124, 125). An abnormal cavernosogram (performed immediately after cavernosometry) shows visualization of penile veins or venous leakage from the crura on films taken immediately after intracavernous injection of diluted contrast.

Penile venous surgery should be limited to men under age 50 because the high incidence of combined arteriogenic and venogenic impotence in older men leads to an unacceptably high failure rate in this age group. Other relative contraindications to the procedure are: diabetes mellitus, generalized arterial disease, and unwillingness or inability to quit smoking. Informed consent should include the risks of possible numbness of the penile skin, shortening of penile length, penile curvature and hematoma. Some investigators also advocate concomitant deep dorsal vein arterialization in order to increase venous resistance (126, 127) .

The lack of long-term success of venous ligation procedures can be partially explained by the complexity of venous drainage of the penis. In the majority of patients, multiple venous leak sites can be visualized on cavernosography. Common leak sites include the superficial and deep dorsal vein, crural veins, corpus spongiosum, and glans penis. The deep dorsal, cavernosal and crural veins are the main venous drainage of the corpora cavernosa and are the most common sites for ligation procedures. Another possible explanation in the widely varied results of venous surgery in the literature may be due to the many variations of surgical techniques developed to treat patients with veno-occlusive erectile dysfunction.

The reasons for failure of the procedure will vary, but include improper diagnosis, incomplete surgical resection of abnormal venous channels, the presence of an arteriogenic component, and the formation of collateral vessels. In a retrospective review of 50 patients (25 successful and 25 failures) who underwent penile venous surgery the most important factors affecting surgical outcome were the findings on cavernosography and the consequent ease of identification and suture-ligation of the abnormal leak(128, 129) . Those patients with leak into unusual sites, such as the glans, corpus spongiosum, crura in combination with a large amount of drainage to the deep dorsal or cavernous vein had the highest rate of failure. If the venous leak could be easily identified on the cavernosogram and could be suture ligated at the tunica albuginea, success was more likely. Development of venous collaterals and persistent venous leakage appears to be a contributing factor in many patients who fail to improve following venous surgery. Factors that predict a poor prognosis include increasing patient age, duration of impotence, multiple leak sites, proximal (crural) venous leak site, and concomitant arteriogenic insufficiency (102, 130). Venous surgery should be performed only in centers with extensive experience in the technique. At present, in our hands approximately 61% of patients with veno-occlusive dysfunction treated with venous surgery are reported as normal or improved after surgical correction. The etiology of veno-occlusive incompetence remains incompletely understood. As our understanding of the cavernosal and sinusoidal function of the penis improves treatment, both medical and surgical, of venous leakage can be directed towards treating the underlying cause rather than a symptom of the disease.