What is the treatment for prolonged rectal bleeding in Irritable Bowel Syndrome (IBS)?

Rectal Bleeding in IBS: This is NOT a Typical IBS Symptom and Requires Investigation

Rectal bleeding is not a feature of IBS and mandates diagnostic evaluation to exclude organic pathology, particularly colorectal cancer, inflammatory bowel disease, and other structural lesions. 1

Critical First Principle: IBS Does Not Cause Rectal Bleeding

• IBS is defined as abdominal pain and discomfort with altered bowel habits in the absence of any mechanical, inflammatory, or biochemical explanation for symptoms. 2
• Rectal bleeding is explicitly NOT part of the IBS symptom complex and should trigger immediate reassessment of the diagnosis. 2
• The presence of visible blood per rectum is a "red flag" symptom that excludes a diagnosis of IBS until organic causes are ruled out. 1

Immediate Diagnostic Approach

Hemodynamic Assessment First

• Assess hemodynamic stability immediately: check pulse, blood pressure, and signs of shock (pulse >100 bpm, systolic BP <100 mmHg indicate severe bleeding). 3
• Establish two large-bore IV lines and begin aggressive fluid resuscitation with normal saline if the patient shows any hemodynamic compromise. 3
• Transfuse red blood cells to maintain hemoglobin >7 g/dL (or >9 g/dL if massive bleeding or cardiovascular comorbidities present). 3

Localization and Endoscopic Evaluation

• Perform colonoscopy as the primary diagnostic procedure in hemodynamically stable patients with rectal bleeding—this has both diagnostic and therapeutic capabilities. 1, 4
• Upper endoscopy (esophagogastroduodenoscopy) should also be performed to exclude upper GI sources, as up to 10% of rectal bleeding originates from the upper gut. 5
• Sigmoidoscopy followed by full colonoscopy is the examination of choice for diagnosis and potential treatment of lower GI bleeding. 4

Key Diagnostic Considerations

• Ulcerative colitis is a leading cause of rectal bleeding in adults (found in 46% of patients with bleeding per rectum in one series), followed by colorectal carcinoma (10%). 4
• In true IBS patients who develop new rectal bleeding, consider that they may have developed a separate condition: diverticulosis and vascular dysplasia account for 30-50% of colonic bleeding. 5
• Obtain biopsies from any suspected lesions during colonoscopy to ensure absence of malignancy. 1

Treatment Based on Underlying Cause (Not IBS Treatment)

If Inflammatory Bowel Disease is Diagnosed

• Rectal bleeding occurs in almost all patients with ulcerative colitis and about 25% of patients with Crohn's disease, but severe hemorrhage occurs in only 1-5%. 6
• For hemodynamically stable IBD patients with bleeding, perform sigmoidoscopy and esophagogastroduodenoscopy first. 1
• Immediate surgery is indicated for unstable patients with hemorrhagic shock who do not respond to resuscitation. 1, 7
• In acute severe ulcerative colitis with refractory hemorrhage non-responsive to medical treatment, subtotal colectomy with ileostomy is the surgical treatment of choice. 1

If Structural Lesions are Found

• Endoscopic therapy should be performed for bleeding ulcers, polyps, or vascular lesions during colonoscopy. 3
• Following successful endoscopic therapy for ulcer bleeding, high-dose proton pump inhibitor therapy is recommended. 3
• CT angiography should be performed in patients with ongoing bleeding who remain hemodynamically stable after resuscitation. 1

Common Pitfalls to Avoid

• Never attribute rectal bleeding to IBS—this is a dangerous diagnostic error that can delay diagnosis of serious conditions like colorectal cancer. 1, 2
• Do not perform endoscopy before adequate hemodynamic resuscitation in unstable patients—this increases mortality. 3
• Do not use antidiarrheal agents like loperamide in patients with bloody diarrhea until infectious causes (particularly Shiga toxin-producing E. coli) are excluded, as this increases risk of hemolytic uremic syndrome. 8
• Avoid delaying colonoscopy in stable patients—early diagnosis within 24 hours reduces mortality. 3

Resuming IBS Treatment Only After Exclusion of Organic Disease

• Once organic causes are definitively excluded and bleeding has resolved, standard IBS treatments can be resumed: soluble fiber (ispaghula 3-4 g/day), antispasmodics for pain, loperamide for diarrhea (if no contraindications), and tricyclic antidepressants (starting at 10 mg amitriptyline) for refractory symptoms. 1
• Regular exercise and first-line dietary advice should be offered to all IBS patients. 1