Lower gastrointestinal bleeding diagnostic study of choice

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief:

Colonoscopy is the gold standard test for the diagnosis of lower gastrointestinal bleeding. However, endoscopy is the investigation of choice in cases of lower gastrointestinal bleeding caused by ischemic colitis.

• Colonoscopy is recommended as the first-line investigation in patients presenting with LGIB.^{[1][2][3][4][5][6][7]}

The advantages of colonoscopy as an initial investigation include:

• The ability to accurately locate and visualize the site of the bleeding, and the potential for therapeutic intervention.

• Disadvantages of colonoscopy include poor visualization in an unprepared colon.
• Risk of fluid overload in the acutely ill patient receiving rapid bowel preparation.

• The sensitivity of colonoscopy in detecting lesions such as angiodysplasia depends on good bowel preparation, and it is estimated to exceed 80%.
• The sensitivity of colonoscopy in detecting bleeding lesions, however, is estimated at 48% to 90%. Therefore, a bleeding site is frequently not identified.
• Despite the disadvantages, complete colonoscopy can be carried out in more than 95% of patients, and a source of bleeding can be identified by colonoscopy in 74% to 82% of patients.
• There is a risk of bowel perforation with colonoscopy, especially in patients with colitis.

• Endoscopy is the investigation of choice for ischemic colitis; however, it is not recommended to perform endoscopy in a patient with severe abdominal pain or peritonitis.^[8][9]
• In cases in which no source of bleeding is seen on colonoscopy, esophagogastroduodenoscopy should be undertaken, as occasionally, brisk UGIB increases transit time and presents as blood per rectum.^[10]
• Endoscopic evaluation of the small bowel may include a combination of endoscopic techniques, such as wireless capsule endoscopy and small bowel enteroscopy (double balloon, push or spiral enteroscopy).
• These modalities are often used if colonoscopy and esophagogastroduodenoscopy have failed to identify the source of gastrointestinal blood loss.
• Advantages of capsule endoscopy are that it is technically easier to use, is noninvasive, and does not require sedation. However, it lacks endoscopic access for therapeutic intervention.
• Capsule endoscopy has a higher diagnostic yield in bleeding patients than enteroscopy, 56% and 26% respectively, and is, therefore, often performed before enteroscopy. If a bleeding lesion is visualized, then endoscopic intervention can be considered

• CTA may be a more appropriate first-line investigation in patients with abdominal pain or suspected peritonitis.^[11]