Biliary tree and portal system
21 named structures.
Draft — not yet clinically reviewed. The structure of this map is checked automatically, but its wording has not been fact-checked against a textbook. Do not rely on it for an exam answer yet.
Hover or tab a structure to trace what it connects to. Some structures reveal further branches.
Clinical detail
- Right hepatic ductSeg V-VIIIAberrant right posterior sectoral duct draining into the common hepatic duct or the cystic duct (a common variant)
- Left hepatic ductSeg II-IV Seg I (mainly)Primary sclerosing cholangitis in a young man with ulcerative colitis and a raised ALP
- GallbladderStone impacted in the neck (Hartmann's pouch) with acute cholecystitis3 questions
- Common hepatic ductStone impacted in the cystic duct or Hartmann's pouch compressing the adjacent common hepatic duct (Mirizzi syndrome)
- Cystic ductStone impacted in the cystic duct
- Common bile duct (bile duct)Gallstone migrating into the bile duct (choledocholithiasis)1 question
- Hepatopancreatic ampulla (of Vater) and sphincter of OddiSmall stone impacted at, or passing through, the ampulla1 question
- Left gastric (coronary) veinForegutPortal hypertension reversing flow in the left gastric vein (hepatofugal flow)
- Inferior mesenteric veinHindgutHaematogenous spread of colon and upper rectal carcinoma1 question
- Short gastric and left gastro-omental veinsForegutSplenic vein occlusion by pancreatitis or a pancreatic tail carcinoma
- Jejunal, ileal, ileocolic, right colic and middle colic veinsMidgutPerforated appendicitis or diverticulitis seeding the ileocolic or sigmoid veins (pylephlebitis)1 question
- Splenic veinForegut HindgutSplenic vein thrombosis from acute or chronic pancreatitis, a pseudocyst or pancreatic carcinoma
- Superior mesenteric veinMidgut ForegutMesenteric venous thrombosis (thrombophilia, oral contraceptive, pancreatitis, cirrhosis, malignancy)1 question
- Hepatic portal veinForegut Midgut HindgutRaised sinusoidal resistance in cirrhosis (or prehepatic portal vein thrombosis, or posthepatic Budd-Chiari syndrome)
- Right and left portal branches, hepatic sinusoids, hepatic veins and IVCHepatic vein thrombosis (Budd-Chiari syndrome: polycythaemia vera, oral contraceptive, pregnancy, thrombophilia)
- Oesophageal portosystemic anastomosis (left gastric to azygos)Portal hypertension with a hepatic venous pressure gradient of 12 mmHg or more
- Rectal portosystemic anastomosis (superior rectal to middle and inferior rectal)Portal hypertension distending the rectal venous plexus1 question
- Paraumbilical portosystemic anastomosis (caput medusae)Portal hypertension driving blood outward through the paraumbilical veins2 questions
- Retroperitoneal portosystemic anastomoses (veins of Retzius) and bare area of the liverSpontaneous splenorenal or gastrorenal shunt in cirrhosis2 questions
Common questions
Which vein is responsible for oesophageal varices?
The left gastric (coronary) vein. Its oesophageal tributaries drain the lower third of the oesophagus into the portal system and communicate in the submucosa with oesophageal veins draining to the azygos and hemiazygos (systemic). When portal pressure rises, flow reverses up the left gastric vein and these submucosal veins distend into varices.
What is the arrangement of the portal triad in the free edge of the lesser omentum?
The bile duct lies anterior and to the right, the hepatic artery proper anterior and to the left, and the portal vein posterior to both. The epiploic foramen (of Winslow) lies immediately behind the free edge, with the IVC behind that, which is why a finger in the foramen can compress all three (the Pringle manoeuvre).
Where is the portal vein formed and by which veins?
Behind the neck of the pancreas at about L1-L2, by union of the splenic vein and the superior mesenteric vein. The inferior mesenteric vein classically joins the splenic vein before this union, though it may join the superior mesenteric vein or the confluence itself. The left and right gastric, cystic and paraumbilical veins drain directly into the portal vein.
Are haemorrhoids a manifestation of portal hypertension?
No. Haemorrhoids are prolapsed anal vascular cushions and are not more common in portal hypertension. The true portosystemic collateral at the rectum is the rectal varix, a dilated submucosal vein arising more than 4 cm above the anal verge from the anastomosis between the superior rectal vein (portal) and the middle and inferior rectal veins (systemic).
How do you distinguish caput medusae from the collateral veins of inferior vena cava obstruction?
By the direction of flow below the umbilicus. In caput medusae, portal blood leaves the umbilicus through the paraumbilical veins, so flow radiates away from it and runs towards the legs in the lower veins. In IVC obstruction the abdominal wall veins carry blood from the legs to the SVC, so flow below the umbilicus runs upward towards the head.
What pressures define portal hypertension?
Normal portal pressure is 5-10 mmHg and the hepatic venous pressure gradient (wedged minus free hepatic venous pressure) is 1-5 mmHg. A gradient above 5 mmHg is portal hypertension, 10 mmHg or more is clinically significant portal hypertension at which varices form, and 12 mmHg or more is the threshold for variceal bleeding and ascites.
What is the normal calibre of the common bile duct?
Up to about 6 mm on ultrasound in an adult with a gallbladder. It widens by roughly 1 mm per decade after 60 and may reach 10 mm after cholecystectomy without being pathological. A duct wider than this suggests obstruction, most often a stone or a pancreatic head or periampullary tumour.