Bleeding from the gastrointestinal tract should always be investigated.
Vomiting blood (haematemesis) can be caused by small injuries to the lining of the oesophagus or stomach, inflammation, ulcers, leaks from dilated blood vessels (varices) or cancer of the oesophagus or stomach. It requires immediate medical attention and usually an urgent endoscopy (OGD).
Bright red rectal bleeding can be caused by piles, trauma to the rectum, polyps, inflammation or cancer. It is usually investigated with a flexible sigmoidoscopy.
Dark red rectal bleeding or passage of black stool indicates bleeding higher up the bowel and can be caused by leaks from small blood vessels (angiodysplasias), inflammation, ulcers, polyps, or cancers. It is usually investigated with a colonoscopy but may also require endoscopy of the upper GI tract (OGD) and investigation of the small bowel.
An iron-deficiency anaemia can also be due to bleeding from the gut.
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