middle hemorrhoidal vein

The middle hemorrhoidal vein, also called the middle rectal vein, is a venous vessel that drains blood from the middle portion of the rectum and empties into the internal iliac vein.

The middle hemorrhoidal vein drains into the internal iliac vein, making it part of the systemic venous system rather than the portal venous system.

Hemorrhoids involve engorgement or prolapse of the hemorrhoidal venous plexuses. The middle hemorrhoidal vein is part of the network of rectal veins that, when dilated or inflamed, contribute to hemorrhoidal disease, particularly in the middle rectal region.

The rectal venous plexus forms an important portosystemic anastomosis. The superior rectal vein drains into the portal system via the inferior mesenteric vein, while the middle and inferior rectal veins drain into the systemic circulation via the internal iliac vein. In portal hypertension, blood can be diverted through this anastomosis, leading to rectal varices.

The middle hemorrhoidal vein accompanies the middle rectal artery, both of which travel through the lateral ligaments of the rectum. Together they supply and drain the lateral walls of the middle rectum and contribute to the pelvic venous plexus.