Chapter 8 HAEMATEMESIS AND MELAENA
INTRODUCTION
Acute gastrointestinal (GI) bleeding is one of the most common emergency conditions and is associated with significant morbidity and mortality. Haematemesis is the vomiting of fresh blood. Haematemesis indicates that bleeding originates from a site proximal to the ligament of Treitz. A history of fresh haematemesis usually implies a significant bleed. Vomiting altered blood that appears like coffee grounds arises from the breakdown of haemoglobin by gastric acid, and often indicates that active bleeding may have ceased. Melaena is the passage of black, tarry stool. It occurs when haemoglobin is converted to haematin by bacterial degradation. Ingestion of as little as 200 mL of blood can produce melaenic stool. Although melaena generally connotes bleeding proximal to the ligament of Treitz, bleeding from the small intestine or proximal colon may also cause melaena, especially when colonic transit is slow. Haematochezia is the passage of pure red blood or blood admixed with stool. It usually occurs as a result of bleeding in the lower GI tract. It can also be present in massive upper GI bleeding (in 10%–15% of cases).
AETIOLOGY
The most common cause of upper GI bleeding is peptic ulcer. This is followed by mucosal erosions, Mallory-Weiss tear, oesophagitis and oesophageal/gastric varices. In the lower GI tract, the most common causes of bleeding are diverticular disease, vascular malformation, inflammatory bowel disease and colorectal neoplasia (Table 8.1). In general, bleeding from the upper GI tract is more common than lower GI tract bleeding.
TABLE 8.1 Causes of acute upper and lower gastrointestinal (GI) bleeding
| Upper GI bleeding | Lower GI bleeding | |
|---|---|---|
| Common |
