- Portosystemic (portocaval) anastomoses: sites where tributaries of the portal vein communicate directly with tributaries of the systemic (caval) veins.
- Form collateral routes for blood in portal obstruction.
Sites of Portosystemic Anastomosis
Sites of portocaval (portosystemic) anastomosis
Site
Lower end of oesophagus
- Portal tributary
- Oesophageal tributaries of left gastric vein
- Systemic tributary
- Oesophageal tributaries of accessory hemiazygos vein
- Clinical result
- Oesophageal varices
Umbilicus
- Portal tributary
- Left branch of portal vein, via paraumbilical veins (of Sappey)
- Systemic tributary
- Superficial veins of anterior abdominal wall
- Clinical result
- Caput medusae
Anal canal
- Portal tributary
- Superior rectal (haemorrhoidal) vein
- Systemic tributary
- Middle and inferior rectal veins, tributaries of internal iliac vein
- Clinical result
- Haemorrhoids (piles)
Retroperitoneal organs (duodenum, ascending and descending colon); renal vein
- Portal tributary
- Veins of these organs; renal vein
- Systemic tributary
- Posterior abdominal wall and renal capsule veins; splenic and azygos veins
- Clinical result
- —
Bare area of liver
- Portal tributary
- Hepatic venules
- Systemic tributary
- Phrenic and intercostal veins
- Clinical result
- —