What is the first test to perform in a patient with lower Gastrointestinal Tract (GIT) bleeding?

First Test for Lower Gastrointestinal Tract Bleeding

The first test that should be performed in a patient with lower GIT bleeding is anoscopy, especially when bright red rectal bleeding is present, as this allows for immediate identification of common anorectal sources such as hemorrhoids. 1

Initial Assessment Based on Hemodynamic Status

Hemodynamically Unstable Patients

• For patients who are hemodynamically unstable (shock index >1) or have active bleeding, CT angiography (CTA) should be the first-line investigation as it provides the fastest and least invasive means to localize the bleeding site before planning endoscopic or radiological therapy 2, 1
• If no source is identified by initial CTA in an unstable patient, an upper endoscopy should be performed immediately, as 10-15% of apparent lower GIT bleeding may have an upper GI source 2, 1
• Patients with severe unremitting bleeding should undergo resuscitation and angiography as soon as possible, bypassing nuclear scintigraphy 2

Hemodynamically Stable Patients

• Direct anorectal inspection with anoscopy should be performed first in stable patients, especially with bright red rectal bleeding, as hemorrhoids account for approximately 14% of lower GIT bleeding 1
• After anoscopy, patients with major bleeding should be admitted for colonoscopy 2
• Patients with minor self-terminating bleeds (Oakland score ≤8 points) with no other indications for hospital admission can be discharged for urgent outpatient investigation 2

Diagnostic Algorithm After Initial Assessment

For Stable Patients After Anoscopy

• Colonoscopy is the preferred diagnostic procedure for most patients with lower GIT bleeding due to its diagnostic and therapeutic capabilities 3
• Colonoscopy should be performed within 24 hours of patient presentation after adequate colon preparation 4
• The diagnostic accuracy of colonoscopy ranges from 72% to 86% in patients with lower GIT bleeding 2

For Stable Patients with Severe but Intermittent Bleeding

• Technetium-99m red blood cell scanning can be considered for patients with severe but intermittent bleeding 2
• A positive red blood cell scan should be followed by urgent angiography within 1 hour 2

Common Pitfalls to Avoid

• Failing to consider an upper GI source in patients with severe hematochezia and hypovolemia (occurs in 10-15% of cases) 1
• Proceeding directly to colonoscopy without first examining the anorectal region, potentially missing easily identifiable sources 1
• Using nasogastric tube placement alone to rule out upper GI bleeding is not reliable 1
• Delaying appropriate imaging in unstable patients while attempting bowel preparation for colonoscopy 1

Special Considerations

• For patients with suspected small bowel bleeding after negative upper and lower endoscopy, video capsule endoscopy should be considered 1
• No patient should proceed to emergency laparotomy unless every effort has been made to localize bleeding by radiological and/or endoscopic modalities 2
• In patients requiring red blood cell transfusion, restrictive transfusion thresholds (Hb trigger 70 g/L and target 70-90 g/L) should be used unless the patient has cardiovascular disease 2