Melena

Description

Blood in the stools can take several forms:

- A small or large amount of bright red or maroon-coloured blood (haematochezia)

- Dark, foul-smelling, tarry stools (melaena stools)

Each represents a different type of bleeding, with its own possible causes.

Causes

Haematochezia usually indicates bleeding from the lower gastrointestinal tract (GIT), and is associated with:

- Haemorrhoids (piles) and anal fissures which, in turn, are usually associated with constipation and straining at stool;

- Proctitis – inflammation of the rectum, or a solitary rectal ulcer;

- Ulcerative colitis – a chronic inflammatory disease of the bowel;

- Polyps of the bowel – may be single or multiple, often causing no symptoms and only minimal bleeding. There may be a familial tendency, and some may undergo malignant change;

- Colon cancer – most patients have rectal bleeding, usually associated with pain and change in bowel habits;

- Bleeding disorders such as haemophilia; and

- Congenitally abnormal blood vessels.

Melaena implies that the blood has been exposed to upper GIT acids and secretions, and has been in the GIT long enough to become altered or partly digested. At any place in the upper GIT the following conditions may cause bleeding and meleana:

- Any state interfering with the normal protective mucus layer of the stomach, such as excess intake of alcohol, aspirin or other non-steroidal anti-inflammatories (for example, diclofenac);

- Gastric/duodenal ulcer disease complication (erosion of an artery) – this is rarely seen nowadays, with excellent medical treatment of these conditions;

- Chronic inflammatory diseases affecting the GIT, for example Crohn's disease;

- Bleeding tendencies due to, for example, heamophilia, or caused by overuse of prescribed anti-clotting agents; and

- Abnormal blood vessels in the GIT, a congenital condition.

Management and tests

Patients with massive bleeds will need admission to a hospital and adequate resuscitation with intravenous fluids and medication. Once they're stabilised and the bleeding is brought under control, investigations can be done.

Questioning and examining the patient will reveal any underlying diseases or contributory causes, such as recent aspirin/Warfarin use. Vomiting, unusual drug intake, alcohol intake, pain, weight loss, loss of appetite – these are all important factors to note. Blood tests (FBC and bleeding screen) may be needed to check for anaemia due to blood loss, and for abnormal bleeding tendencies.

Patients suspected of having an upper GIT cause for bleeding (for instance esophagus, stomach, duodenum or small bowel) will need to have a barium swallow/meal and/or endoscopy to look inside the GIT, and possibly take tissue samples for analysis.

Tests for suspected lower GIT pathology will include endoscopy with or without biopsy (from anus to caecum), possible barium studies and scans.

Treatment

This will depend on the causes found, and may included medical management of inflammatory disorders, changing prescribed medication or assuming stricter dosage control of essential medication like Warfarin. Absent or inadequate clotting factors can be individually replaced, and the patient then referred to a haematologist for subsequent long-term management.

Cancers, depending on the type and stage, may benefit from surgery: certain types benefit more from radiotherapy or chemotherapy, administered by oncologists.

Isolated colon polyps can be removed endoscopically, but long-term repeat screening is advised.

Follow-up investigations are decided upon by the specialists concerned.

(Dr AG Hall)