Nursing care
Why portal hypertension creates oesophageal varices that can bleed
Written and reviewed by Dana Whitfield, RN, MSN · 4 min read · Updated October 2026
Short answer
In cirrhosis, scar tissue increases resistance to blood flowing through the liver, so pressure builds in the portal vein. Blood reroutes through collateral veins that connect the portal and systemic circulations, including thin-walled veins in the lower oesophagus and stomach. These swell into varices, which can rupture and cause sudden, painless and often massive upper GI bleeding.
Why blood backs up behind a scarred liver
The portal vein carries blood from the intestines and spleen through the liver before it returns to the heart. In cirrhosis, fibrosis and regenerating nodules narrow the sinusoids, increasing resistance. At the same time, vasodilation in the gut circulation increases blood flow into the portal system. Higher resistance plus higher inflow raises portal pressure.
The spleen sits upstream and enlarges as blood backs up into it, which helps explain the low platelet count seen in many clients with portal hypertension. Toxins absorbed from the gut can also bypass the liver through the same rerouted vessels, contributing to hepatic encephalopathy. Varices are one part of a wider pattern produced by the same pressure.
How collateral veins become varices
Where portal and systemic veins meet, small connecting vessels normally carry little blood. When portal pressure rises, blood is diverted through them to reach the heart another way. Veins in the submucosa of the lower oesophagus and upper stomach enlarge and become tortuous varices. Similar diversion produces rectal varices and the dilated abdominal wall veins called caput medusae.
Variceal walls are thin and poorly supported, and they lie just beneath the lining exposed to food and acid. Bleeding is rare unless the pressure gradient across the liver exceeds a threshold, and larger varices with red markings on endoscopy carry more risk. When a varix ruptures, bleeding is typically sudden, painless and can be massive, with high short-term mortality.
Translating the mechanism into precautions
Anything that sharply raises pressure in the abdomen or damages the oesophageal lining is a concern for clients with known varices. Teaching commonly includes avoiding straining and heavy lifting, treating constipation, and reporting vomiting promptly. Alcohol avoidance protects the liver. Nonselective beta blockers are prescribed to lower portal pressure, so the nurse checks heart rate and blood pressure before giving them.
Low platelets and impaired production of clotting factors add to bleeding risk. Watch for haematemesis, melena, dizziness, rising heart rate and falling blood pressure, and new confusion, which can be triggered by blood in the gut. In acute bleeding, expect airway protection, careful blood transfusion, octreotide and endoscopic banding under medical direction; over-transfusion can raise portal pressure and worsen bleeding.
Why varices are found by surveillance, not symptoms
Varices cause no symptoms until they bleed. For this reason, people with cirrhosis are commonly offered endoscopic surveillance to find varices and judge their size and risk features. Treatment choices, such as a nonselective beta blocker or banding, depend on what is found. Clients may not understand why they need a camera test when they feel well, so explain the purpose plainly.
Banding places small elastic bands around varices so they scar and close, usually over several sessions. After banding, clients may have chest discomfort or difficulty swallowing for a short time, and the provider gives dietary advice. Report severe chest pain, fever or vomiting blood after the procedure. The underlying portal pressure remains, so new varices can develop and follow-up continues.
Worked scenario: which teaching point matters most?
A hypothetical client with cirrhosis and varices on surveillance is preparing for discharge. Which statement shows understanding? Options include planning to lift heavy boxes now that the client feels better, taking a laxative only if constipated for a week, or reporting black stools or vomiting blood straight away and continuing the prescribed beta blocker.
The third statement is correct. It shows the client recognises early signs of variceal bleeding and the purpose of the beta blocker in lowering portal pressure. Heavy lifting raises intra-abdominal pressure, and waiting a week with constipation invites straining. A client who can name the warning signs is better placed to get help early.
Sources and further reading
Merck Manual Professional: Portal hypertension. Increased sinusoidal resistance, portosystemic collaterals, caput medusae, splenomegaly, encephalopathy, bleeding threshold and beta blockers.
Merck Manual Professional: Varices. Painless massive bleeding, high-risk features, octreotide, banding and the caution against over-transfusion.
NIDDK: Symptoms and causes of cirrhosis. Bleeding from enlarged veins in the oesophagus or stomach and easy bruising as cirrhosis progresses.
The next step on this is the same as on everything else here: answer questions and read the rationales. Our gastrointestinal practice questions are the closest set to what this page covers.
Common questions
Why are varices most common in the lower oesophagus?
The lower oesophagus is a natural meeting point of portal and systemic veins. Raised portal pressure diverts blood through these thin submucosal veins, which enlarge into varices.
Why is variceal bleeding usually painless?
The bleeding comes from a ruptured vein in the lining rather than from an inflamed ulcer. Clients may notice vomiting blood, black stool or faintness without pain.
Why do nonselective beta blockers help?
They reduce blood flow into the portal system and lower portal pressure, reducing the chance of bleeding. Check pulse and blood pressure and report symptomatic low readings.