Review Article

The Diagnosis and Investigation of Obscure Gastrointestinal Bleeding

K. Liu; A. J. Kaffes

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

Nuclear Scans and Angiography

Radionuclide scans with technetium-99m-labelled red cells are a sensitive, non-invasive technique for detecting both arterial and venous GI bleeding. However, its role in patients with obscure GI bleeding is limited to patients presenting with bleeding at a rate of >0.1 mL/min.^[9,53] Delayed scans, although useful for detecting intermittent bleeding, can be misleading by identifying pooled blood at points separate from the bleeding site. In general, its ability to localise bleeding lesions, especially in the foregut, is reported to be poor.^[9]

Angiography identifies bleeding lesions if the rate is >0.5 mL/min and is better at localising the source of bleeding than nuclear scans.^[9] It also detects non-bleeding lesions such as angioectasias, tumours and inflammatory lesions based on characteristic vascular patterns.^[9] Angiography provides the added advantage of therapeutic intervention with embolisation once a bleeding source is found. It is generally reserved for situations where other modalities have failed. Although provocative angiography (with anticoagulants, vasodilators and thrombolytics) has been shown to be safe in some studies,^[54] it use is rarely recommended because of risk of uncontrolled bleeding and low diagnostic yield.

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Cite this: The Diagnosis and Investigation of Obscure Gastrointestinal Bleeding - Medscape - Aug 01, 2011.

Table 1. Causes of obscure gastrointestinal bleeding
Upper GI lesions
Cameron erosions	5–15
Angioectasia	5–10
Varices	1–5
Dieulafoy lesion	2–3
Gastric antral vascular ectasia (GAVE)	1–2
Portal hypertensive gastropathy	1–2
Small bowel lesions
Angioectasia	20–55
Small bowel tumours	10–20
Crohn's disease	2–10
Coeliac disease	2–5
Meckel's diverticulum	2–5
NSAID enteropathy	5
Dieulafoy lesion	1–2
Ectopic varices	1–2
Portal hypertensive enteropathy	1–2 (but 60–70in those with portal hypertension)
Radiation enteritis	<1
Lower GI lesions
Angioectasias	2
Neoplasms	1
Dieulafoy lesion	<1
Rare lesions
Haemobilia	<1
Haemosuccus pancreaticus	<1

Values are expressed as percentages.^{27,40,65–69}

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