Upper and lower gastrointestinal bleeding !

Syndrome

Bleeding in the gut: vomiting blood, black stools or red blood from the rectum. The first step is to see whether the patient is stable.

Updated 2026-11-01

See it in 3D: Esophagus · Stomach · Duodenum · Gastroduodenal artery · Gastric arteries · Sigmoid colon · Rectum

What it is

Gastrointestinal bleeding is blood loss from anywhere in the digestive tract. It is called upper if the source lies above the ligament of Treitz (esophagus, stomach, duodenum) and lower if below it. At the bedside the priority is to judge the hemodynamic impact; the look of the blood points to the source.

Key findings

Vital signs and orthostatics first: heart rate, blood pressure, capillary refill, mental state and urine output.
Pale mucosa and cold, clammy skin.
Rectal exam: stool color (melena, red blood), masses and hemorrhoids.
Liver-disease stigmata and splenomegaly: suggest a variceal source.
Epigastric pain, use of NSAIDs or anticoagulants; repeated vomiting before the bleed suggests Mallory-Weiss.
Weight loss and a change in bowel habit in an older adult suggest colorectal cancer.

Pathophysiology

Blood passing through the stomach and gut is partly digested: hemoglobin is oxidized and turns black, giving melena and the coffee-ground look.
The more distal and the faster the bleed, the redder the blood that leaves the rectum.
Volume loss triggers compensation: tachycardia and peripheral vasoconstriction; blood pressure falls when compensation runs out.
Hemoglobin takes hours to fall because whole blood is lost at first; it drops when extravascular fluid enters the vessels (hemodilution).
In upper bleeding, digested blood raises blood urea.

Common causes

Upper: gastric or duodenal peptic ulcer, esophageal and gastric varices, Mallory-Weiss tear, esophagitis, erosive gastritis and tumors.
Lower: diverticulosis, angiodysplasia, colorectal cancer and polyps, ischemic colitis, inflammatory bowel disease and hemorrhoids.
Risk factors: NSAIDs, anticoagulants, antiplatelet drugs, alcohol and cirrhosis.

Tests that confirm it

Serial blood counts, clotting tests, urea and creatinine, and blood typing.
Upper endoscopy for upper bleeding; colonoscopy for lower bleeding.
CT angiography when bleeding is active and endoscopy cannot find the source.

Test yourself

Think of the answer, then tap the question to see it.

Which anatomical landmark separates upper from lower gastrointestinal bleeding?

The ligament of Treitz (suspensory ligament of the duodenum), at the duodenojejunal junction.

Why is melena black?

Blood is partly digested as it passes through the gut and hemoglobin is oxidized; so it usually means an upper source, though it can come from the small bowel or right colon.

Why does a normal hemoglobin not rule out a severe recent bleed?

At first whole blood is lost and the concentration does not change; hemoglobin falls hours later, when extravascular fluid dilutes the blood.

Which substances can darken stool and mimic melena?

Oral iron and bismuth subsalicylate; true melena is sticky, shiny and foul-smelling.

Add to my cards (4)

See it in 3D

The structures of Durgical's 3D anatomy where it is found.

← All of the clinical exam

Educational content on the clinical exam; it is learned and practised under supervision. It does not replace assessment by a health professional and is not for self-diagnosis.

Sources: GI Bleed | Gastrointestinal Bleeding: MedlinePlus (MedlinePlus, U.S. National Library of Medicine, 2026); 18.3 Erythrocytes - Anatomy and Physiology 2e | OpenStax (OpenStax, Rice University, 2022).

Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake

Representative model, for educational purposes only.