What are the causes of hematemesis?

Hematemesis is a serious symptom, typically indicating bleeding from the upper gastrointestinal tract that is vomited out through the mouth. The main causes include:

1. Upper gastrointestinal diseases: These are the most common causes, including gastric ulcers, duodenal ulcers, gastritis, esophagitis, ruptured esophageal varices, gastric cancer, etc.

2. Portal hypertension: Portal hypertension caused by cirrhosis can lead to varices in the lower esophagus and gastric fundus; when these varicose veins rupture, massive hematemesis may occur.

3. Acute gastric mucosal lesions: Such as stress ulcers, drug-induced gastric mucosal injury, and alcoholic gastritis.

4. Vascular malformations or vascular anomalies: For example, Dieulafoy's disease, a rare condition characterized by abnormal dilation of a small artery in the stomach, which can cause sudden massive bleeding.

5. Systemic diseases: Such as blood disorders, infectious diseases, autoimmune diseases, etc., which may also cause hematemesis.

However, the severity of hematemesis depends on the amount and speed of bleeding. Immediate medical attention should be sought once hematemesis occurs.