Venous drainage of the urinary bladder.

The venous drainage of the urinary bladder was studied in 20 pelvic halves (14 males and 6 females). Vesical and prostatic plexuses draining the bladder (vesical only in females) were found in 16 cases; they supplied blood to the internal iliac vein--usually by two to five veins--the most common number being three. One vein always drained the prostatic plexus. The vesical and prostatic plexuses were absent in 4 male cases, where the vesical veins issuing from the bladder wall drained directly the internal iliac vein. Their number in such cases was minimal: between one and two only, on each side. The union of a vesical vein issuing from any of the two mentioned plexuses (when found) with the obturator, prostatic or vaginal vein was common. A shunt from a common trunk of united obturator and vesical veins to the external iliac vein was noticed in some cases. Occasionally, an inferior vesical vein ending in the obturator vein accompanied an inferior vesical artery initiating from the obturator artery.