What is the best course of action for a patient with rectal bleeding, constipation, and stomach pain while awaiting colonoscopy results, currently taking Miralax (polyethylene glycol) and Fiber Lax?

Management of Rectal Bleeding, Constipation, and Stomach Pain While Awaiting Colonoscopy

For a 56-year-old male with rectal bleeding, constipation, and stomach pain awaiting colonoscopy, the most appropriate immediate action is to perform a direct anorectal examination to rule out anorectal causes of bleeding while continuing polyethylene glycol and adding a stimulant laxative to address constipation. 1

Initial Assessment

• Bright red rectal bleeding with constipation in a patient over 50 years old requires urgent evaluation due to the 6% risk of underlying colorectal cancer 1
• The combination of rectal bleeding, change in bowel habits (from diarrhea to constipation), and abdominal pain significantly increases the likelihood of serious pathology 2
• Rectal bleeding with blood mixed with stool, change in bowel habits, and abdominal pain are significantly associated with serious disease 2

Immediate Management While Awaiting Colonoscopy

Anorectal Examination

• Perform direct anorectal examination (proctoscopy or anoscopy) immediately to identify potential anorectal sources of bleeding 1
• Benign anorectal conditions account for 16.7% of diagnoses in patients with lower GI bleeding 1
• Assessment of the anal canal and rectum should be undertaken in all patients presenting with lower GI bleeding 1

Constipation Management

• Continue polyethylene glycol (Miralax) as it is effective for functional constipation 3
• Add a stimulant laxative (such as bisacodyl or senna) to the current regimen of polyethylene glycol and fiber to address the ongoing constipation 1
• Monitor for worsening symptoms - if rectal bleeding, nausea, bloating, cramping or abdominal pain worsen, discontinue polyethylene glycol and seek immediate medical attention 4

Diagnostic Considerations

• Colonoscopy remains the preferred investigation for rectal bleeding as it has diagnostic yields of 42-90% 1
• The presence of both rectal bleeding and change in bowel habits warrants colonoscopy within 2 weeks due to increased risk of colorectal cancer 1
• Diagnostic yield for colorectal neoplasia is high (33.6%) in patients with rectal bleeding, and still significant (22-27%) in those with abdominal pain or change in bowel habits 5

Warning Signs Requiring Immediate Attention

• If the patient becomes hemodynamically unstable (shock index >1) or shows signs of active bleeding, CT angiography should be performed before colonoscopy 1
• Worsening abdominal pain, increasing rectal bleeding, fever, or signs of peritonitis require immediate evaluation for potential complications such as perforation 1
• If rectal bleeding persists or worsens while taking polyethylene glycol, discontinue use and seek immediate medical attention 4

Preparation for Upcoming Colonoscopy

• Ensure adequate bowel preparation with polyethylene glycol solution before the scheduled colonoscopy 1
• Polyethylene glycol provides better diagnostic yields and reduces the need for repeat colonoscopy compared to other preparation methods 1
• If the colonoscopy is scheduled more than 8-9 hours after bowel preparation, consider adding lactulose to improve bowel cleanliness 6

Follow-up Recommendations

• Complete the pending H. pylori stool test and CBC to rule out other potential causes of symptoms 1
• If upper GI symptoms are prominent, consider upper endoscopy as up to 15% of patients with serious hematochezia may have an upper GI source 1
• Maintain a symptom diary documenting frequency and characteristics of bowel movements and bleeding episodes to assist in diagnosis 1