How to manage suspected colitis in a patient with abdominal pain and nausea?

Approach to Suspected Colitis in a 35-Year-Old Female with Abdominal Pain and Nausea

Begin with comprehensive stool testing and laboratory workup to exclude infectious causes before initiating any immunosuppressive therapy, followed by endoscopic evaluation with biopsies to establish the specific diagnosis and guide targeted treatment. 1

Initial Laboratory Evaluation

The following laboratory tests are mandatory at presentation:

• Complete blood count to assess for anemia, leukocytosis, and thrombocytosis 1
• C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) as inflammatory markers, with CRP being more sensitive for acute evaluation 1
• Comprehensive metabolic panel including electrolytes, liver enzymes, renal function, and serum albumin to assess nutritional status and degree of inflammation 1
• Fecal calprotectin or fecal lactoferrin to confirm intestinal inflammation, with lactoferrin showing 90% sensitivity for histologic inflammation 1, 2

Mandatory Infectious Workup

It is mandatory to exclude infectious causes before initiating any treatment, particularly immunosuppressive therapy: 1

• Clostridioides difficile toxin testing in all patients 1, 2
• Stool cultures for bacterial pathogens including Salmonella, Shigella, Campylobacter, and E. coli 2, 3
• Cytomegalovirus (CMV) testing especially if the patient has risk factors for immunocompromise 1, 2
• Ova and parasites if clinically indicated based on travel history or epidemiologic factors 2, 3

A critical pitfall is initiating corticosteroids or other immunosuppressive therapy before excluding infectious etiologies, which can lead to severe complications. 1

Imaging Studies

Obtain contrast-enhanced computed tomography (CT) of the abdomen and pelvis to evaluate for complications and assess disease extent: 1, 2

• CT is the key study in the emergency setting for detecting extra-luminal complications such as abscesses, fistulae, and bowel perforation 1
• Look for colonic wall thickening, peri-colonic stranding, and ascites 2
• Assess for colonic dilatation (≥5.5 cm transverse colon diameter), which indicates severe disease requiring urgent intervention 1

Endoscopic Evaluation

Flexible sigmoidoscopy or colonoscopy with biopsies should be performed when stool inflammatory markers are elevated or symptoms persist: 1, 2

• Endoscopy is the reference standard for diagnosis and predicts response to treatment 1
• Approximately 95% of inflammatory colitis cases have inflammation in the left colon, making flexible sigmoidoscopy often adequate 1
• Full colonoscopy should be avoided in severe colitis due to perforation risk 1
• Biopsies documenting chronic inflammation confirm the diagnosis of inflammatory bowel disease 4, 5

Treatment Algorithm Based on Etiology

If Infectious Colitis is Confirmed:

• For C. difficile: Oral vancomycin or fidaxomicin as first-line treatment 2
• For bacterial pathogens: Targeted antibiotic therapy based on culture results; empiric azithromycin 1000mg single dose for febrile dysenteric diarrhea if invasive bacterial pathogens suspected 3
• Avoid antibiotics for Shiga toxin-producing E. coli (STEC) as they may precipitate hemolytic uremic syndrome 3

If Inflammatory Bowel Disease (IBD) is Suspected:

For mild to moderate disease:

• Oral mesalamine combined with topical mesalamine (rectal suppositories or enemas) for distal disease 1, 2, 6
• Combination therapy is more effective than either agent alone 1

For moderate to severe disease:

• Oral prednisolone 40mg daily, tapered gradually over 8 weeks according to response 1
• Consider early biologic therapy with infliximab or vedolizumab if corticosteroid-refractory (no improvement within 72 hours) 1, 2

For severe colitis meeting Truelove and Witts criteria:

• Immediate hospital admission with joint medical-surgical management 1
• Intravenous corticosteroids as first-line therapy 1, 2
• Daily monitoring of vital signs, stool frequency, and inflammatory markers 1
• Maintain hemoglobin >10 g/dL with transfusion if needed 1
• Subcutaneous heparin for thromboembolism prophylaxis 1
• 25-30% of severe colitis cases require colectomy—maintain close surgical consultation 1

Supportive Care Measures

• Adequate hydration and electrolyte replacement are essential for all patients 1, 2
• Avoid NSAIDs as they can exacerbate colonic inflammation 2
• Loperamide may be used cautiously for mild diarrhea only after infectious causes are excluded 1, 2
• Consider nutritional support if the patient is malnourished 1

Warning Signs Requiring Urgent Intervention

• Severe abdominal pain, fever, or signs of peritonitis 2
• Significant rectal bleeding 2
• Evidence of bowel perforation or toxic megacolon on imaging 2
• Colonic dilatation ≥5.5 cm on plain radiograph 1

Follow-Up Strategy

• Monitor clinical response through symptom assessment and repeat inflammatory markers 2
• Follow-up endoscopy may be necessary to confirm mucosal healing in moderate to severe cases, as mucosal healing predicts lower relapse rates 1, 2
• Lifelong maintenance therapy is generally recommended for all IBD patients to reduce relapse risk and potentially decrease colorectal cancer risk 1