What is the first test that should be performed 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 may indicate an anorectal source of hemorrhage. 1

Initial Assessment Based on Hemodynamic Status

The approach to lower GIT bleeding should be guided by the patient's hemodynamic status:

For Hemodynamically Unstable Patients (Shock Index >1):

• CT angiography (CTA) should be the first-line investigation as it provides the fastest and least invasive means to localize the bleeding site 1
• CTA is preferred over colonoscopy in unstable patients as it can identify bleeding sources in the upper GI tract or small bowel, is widely available, and requires no bowel preparation 1

For Hemodynamically Stable Patients:

• Direct anorectal inspection with anoscopy should be performed first, especially when bright red rectal bleeding is present 1
• This allows for immediate identification of common anorectal sources such as hemorrhoids, which account for approximately 14% of lower GIT bleeding 1

Diagnostic Algorithm for Lower GIT Bleeding

1. Initial evaluation: Determine hemodynamic stability (shock index = heart rate/systolic BP) 1

2. For bright red rectal bleeding:

   • Perform anoscopy/proctoscopy first to identify anorectal sources 1
   • If no source is identified, proceed to next appropriate test based on clinical status 1

3. For hemodynamically unstable patients:

   • Perform CTA to rapidly localize the bleeding source 1
   • Consider upper GI endoscopy if CTA is negative, as 10-15% of apparent lower GIT bleeding may have an upper GI source 1

4. For hemodynamically stable patients with major bleeding:

   • After anoscopy, proceed to colonoscopy within 24 hours after adequate bowel preparation 1, 2

Importance of Anorectal Examination

• Bright red rectal bleeding often indicates an anorectal source that can be immediately identified with anoscopy 1
• Anorectal causes (such as hemorrhoids) account for a significant percentage of lower GIT bleeding cases 1
• Direct visualization allows for both diagnosis and potential therapeutic intervention 3

Common Pitfalls to Avoid

• Failing to consider an upper GI source in patients with severe hematochezia and hypovolemia (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 to rule out upper GI bleeding is not reliable and is not routinely recommended 1
• Delaying appropriate imaging in unstable patients while attempting bowel preparation for colonoscopy 1

Subsequent Testing After Initial Assessment

• If anoscopy and CTA do not identify the bleeding site, a full colonoscopy should be performed 1
• For stable patients with major bleeding, colonoscopy should be performed within 24 hours after adequate bowel preparation 2
• For patients with suspected small bowel bleeding after negative upper and lower endoscopy, video capsule endoscopy should be considered 4