Volume-dependent intracavernous hemodilution during pharmacologically induced penile erections.

The change in the cavernous hematocrit following induction of pharmacological erection by an intracavernous injection of papaverine hydrochloride was documented in normal controls and patients with impotence. Blood samples taken from the penile cavernosa showed a significantly lower hematocrit compared to the systemic venous blood in all normal subjects. The decrease in the cavernous hematocrit was attributable to dilution of the cavernous blood pool by the injected volume of the drug, since this was not observed in erections produced by visual sexual stimulation. It appears that a restriction of the cavernous venous outflow in response to papaverine injection causes sequestration of the diluted blood in the cavernous compartment. The degree of cavernous hemodilution was found to aid in the differential diagnosis and was especially valuable in differentiating patients with arteriogenic impotence from those with venous leakage.