Obscure Gastrointestinal Bleeding

Obscure gastrointestinal bleeding is recurrent or persistent bleeding (overt or occult) for which no source is found after bidirectional endoscopy.

• It accounts for about 5 percent of gastrointestinal bleeding; the small bowel is the source in most.
• Causes: small bowel angioectasia (most common over age 60 years), Crohn disease, NSAID enteropathy, tumours (GIST, lymphoma, carcinoid, adenocarcinoma), Meckel diverticulum (under 40 years), Dieulafoy lesion, polyposis syndromes, ulcers and varices.
• Overt obscure bleeding presents with visible blood; occult obscure bleeding presents as iron deficiency or positive faecal test.

Recurrent melaena or haematochezia, iron deficiency anaemia, transfusion dependence.

• Associated conditions: aortic stenosis (acquired von Willebrand deficiency), chronic kidney disease, hereditary haemorrhagic telangiectasia, cirrhosis, left ventricular assist devices.
• Differential diagnosis: missed lesions at routine endoscopy (about 25 percent), including Cameron lesions, gastric antral vascular ectasia, colonic angioectasia, haemorrhoids, and haemobilia.
• Complications: transfusion dependence, iron overload from repeated transfusion, cardiac decompensation, delayed tumour diagnosis.

Repeat upper endoscopy (including push enteroscopy) and colonoscopy if the first examination was suboptimal.

• Capsule endoscopy (diagnostic yield 60 percent in overt bleeding; avoid with suspected stricture, otherwise use a patency capsule first).
• Device-assisted enteroscopy (single or double balloon) for targeted biopsy and therapy.
• CT enterography or MR enterography for masses and inflammation; CT angiography for active bleeding.
• Technetium pertechnetate scan for Meckel diverticulum; intraoperative enteroscopy as last resort.
• Check for aortic stenosis with echocardiography and von Willebrand function.

Supportive: iron replacement (oral 200 mg ferrous sulfate daily or intravenous ferric carboxymaltose 1000 mg), transfusion for haemoglobin below 7 g/dL, review of antithrombotic therapy.

Pharmacological (for recurrent angioectasia bleeding when endoscopic therapy is not possible):

• Octreotide long-acting 20 mg IM every 4 weeks for 12 months.
• Thalidomide 100 mg daily (strict contraception; neuropathy and thrombosis risk).
• Tranexamic acid 1 g three times daily may be tried; avoid in thrombosis risk.
• Crohn disease and NSAID enteropathy: stop the NSAID; treat Crohn disease with prednisolone 40 mg daily tapering over 8 weeks and add azathioprine 2 to 2.5 mg/kg daily.

Procedures: argon plasma coagulation or clip placement at enteroscopy; angiographic embolisation; surgical resection guided by marking (Meckel diverticulectomy, tumour resection).

Special groups: aortic stenosis with Heyde syndrome may need valve replacement; patients with hereditary haemorrhagic telangiectasia need specialist care.

Red flags: haemodynamic instability, transfusion above 2 units per month, capsule retention, unexplained weight loss.

Follow-up: haemoglobin every 3 months, repeat capsule endoscopy if rebleeding after a negative first examination.