Review Article

The Diagnosis and Investigation of Obscure Gastrointestinal Bleeding

K. Liu; A. J. Kaffes


Aliment Pharmacol Ther. 2011;34(14):416-423. 

In This Article

Capsule Endoscopy

The development of the wireless capsule endoscopy has revolutionised the investigation of the small intestine. It offers a safe, minimally invasive and effective tool for the next step in the evaluation of GI bleeding after negative standard endoscopies. The latest systematic review of 227 articles on CE revealed OGIB was by far the most common indication comprising 66% of patients undergoing CE.[6] The diagnostic yield of CE in OGIB is 60.5% with the most common diagnosis being angiodysplasias accounting for 50% of lesions followed by ulcers (26.8%) and neoplastic lesions (8.8%).[6] A positive finding is generally observed more often in patients with obscure overt bleeding compared with those with obscure occult bleeding,[7–9] although this is not confirmed by all studies.[10,11] Other factors such as performing CE within 2 weeks of a bleeding episode, Hb <10 g/dL, bleeding for >6 months and >1 bleeding episode also increase the yield of the examination.[12,13]

Capsule endoscopy has consistently been shown to be superior to push enteroscopy (PE) and small bowel radiography in detecting small bowel lesions.[7,8,14,15] A meta-analysis of studies comparing the yield of CE to other diagnostic modalities in OGIB showed that in 14 studies, the yield of CE was double that of PE (63% vs. 28%).[14] The same meta-analysis reported the yield of CE was also found to be higher than small bowel radiography for clinically significant lesions (42% vs. 6%) in pooled data from three studies.[14] These findings are supported by another meta-analysis of 24 studies (530 patients), which reported the yield of CE (for all indications) to be 87% compared to 14.8% and 9.9% for PE and small-bowel series respectively.[15]

In terms of clinical outcomes, Mylonaki et al. found that capsule endoscopy led to an alteration in therapy in 25/38 (66%) of patients with OGIB.[16] Enteroclysis, in comparison changes the clinical management in only 10% of patients.[17] Pennazio et al. showed resolution of bleeding in 86.9%, 41% and 69.2% of patients with ongoing overt obscure bleeding, previous overt obscure bleeding and occult obscure bleeding respectively.[18] The rate of rebleeding in patients with OGIB and a negative CE is less than 6%.[19]

The main limitation of capsule endoscopy is its inability to obtain biopsies or administer therapy. CE also does not obtain satisfactory views of the oesophagus, stomach or colon and should not replace or bypass upper or lower endoscopies.[20] Diagnostic yield may be reduced in patients with poor bowel preparation or incomplete examinations because of delayed gastric emptying or failure of capsule to enter duodenum within 1.5 h. The most common complication is capsule retention (or non-natural excretion), which occurs in 1.4% of patients with OGIB.[6] Risk factors for capsule retention include NSAID use abdominal radiation injury, extensive Crohn's disease and previous major abdominal surgery. There have been no reported deaths from CE to date.[6] Patients with pacemakers or defibrillators should be closely monitored during CE.


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