From the Guidelines
For rectal bleeding, I recommend ordering a complete blood count (CBC) to assess for anemia and determine the severity of blood loss, along with coagulation studies (PT/INR, PTT) to rule out bleeding disorders, as suggested by 1 and 1.
Initial Evaluation
The initial evaluation of rectal bleeding should include a focused medical history and a complete physical examination, including a digital rectal examination, to rule out other causes of lower gastrointestinal bleeding 1.
- Vital signs should be checked to determine the severity of the bleeding.
- Hemoglobin and hematocrit levels should be assessed to evaluate the severity of the bleeding.
- Coagulation studies, such as PT/INR and PTT, should be performed to rule out bleeding disorders.
- Blood typing and cross-matching should be considered in cases of severe bleeding 1.
Imaging Studies
For imaging, the following studies are recommended:
- Anoscopy or flexible sigmoidoscopy to directly visualize the rectum and distal colon 1.
- Colonoscopy, which is the gold standard for evaluating the entire colon and identifying the bleeding source 1.
- In cases of brisk bleeding, CT angiography can locate active bleeding sites, while tagged red blood cell scans are useful for intermittent bleeding 1.
- For suspected inflammatory bowel disease, consider CT or MRI enterography 1.
Additional Tests
Additional tests that may be useful in the evaluation of rectal bleeding include:
- Fecal occult blood testing to confirm the presence of blood in stool.
- Basic metabolic panel (BMP) to evaluate kidney function and electrolyte balance.
- Endoscopic ultrasound (EUS) with color Doppler evaluation to detect deep rectal varices or to evaluate the hemodynamics of varices 1.
- Contrast-enhanced CT-scan or MRI angiography in cases where EUS is not available or in pregnant patients 1.
These tests help determine the cause of rectal bleeding, which may include hemorrhoids, anal fissures, diverticular disease, inflammatory bowel disease, polyps, or colorectal cancer. The specific tests ordered should be tailored to the patient's age, bleeding severity, and associated symptoms.
From the Research
Laboratory Tests and Imaging Studies for Rectal Bleeding
The evaluation of rectal bleeding (hematochezia) involves various laboratory tests and imaging studies to determine the underlying cause. The following are some of the indicated tests and studies:
- Complete blood count (CBC) to check for anemia or blood loss 2
- Coagulation studies to evaluate bleeding disorders 2
- Liver function tests to assess liver disease 2
- Electrolyte panel to check for electrolyte imbalances 2
- Stool tests for occult blood or infection 2
Imaging Studies
- Colonoscopy is the gold standard for evaluating the colon and rectum for bleeding sources 3, 4, 5
- Flexible sigmoidoscopy may be sufficient for patients with classic "outlet" bleeding and no other indications for colonoscopy 3
- Computed tomography (CT) angiography may be used to locate the site of bleeding in patients with hemodynamic instability 2
- Barium studies may be used to evaluate the colon, but colonoscopy is generally preferred 5
Risk Stratification
- Patients with rectal bleeding can be stratified into high-risk and low-risk groups based on their symptoms and medical history 6
- High-risk patients are more likely to have colorectal cancer and should undergo prompt evaluation with endoscopy 6
- The use of a symptom checklist and referral physician designation can help identify high-risk patients 6
Management
- Patients with acute lower gastrointestinal bleeding should undergo initial assessment, including history, physical examination, and laboratory tests 2
- A risk score can be used to aid in decision-making, but should not replace clinician judgment 2
- Patients with hemodynamic instability should undergo computed tomography angiography to locate the site of bleeding 2
- Endoscopy should be performed in patients with major acute lower gastrointestinal bleeding, but the timing may vary depending on the patient's condition 2