Gastrointestinal · Year 2 · from Gastrointestinal
Case 3: Toxic Megacolon
Patient Presentation
Demographics: 42-year-old male
Chief Complaint: Severe abdominal pain and distension with fever
History of Present Illness: The patient has a 10-year history of ulcerative colitis, currently on mesalamine. He was experiencing a moderate flare with bloody diarrhea for 2 weeks when symptoms abruptly changed 48 hours ago. His diarrhea decreased but was replaced by severe abdominal distension and pain. He developed high fever and feels very weak. He has had minimal bowel movements in the past day despite previous diarrhea.
Past Medical History: Pancolonic ulcerative colitis diagnosed 10 years ago
Medications: Mesalamine (admits to irregular adherence)
Physical Examination
- Vital Signs: BP 88/55 mmHg, HR 128 bpm, Temperature 39.2C, RR 24/min
- General: Toxic-appearing, diaphoretic, altered mental status
- Abdomen: Markedly distended, diffusely tender with guarding, tympanitic, diminished bowel sounds
- Rectal: Empty vault, small amount of blood
Workup and Results
- CBC: WBC 22,500 with bandemia, Hemoglobin 9.8 g/dL
- BMP: Na 132, K 2.8, Cr 1.8 mg/dL
- Lactate: 4.2 mmol/L (elevated)
- Albumin: 2.2 g/dL
- Abdominal X-ray: Transverse colon diameter 8 cm (>6 cm is diagnostic); loss of haustral markings; no free air
- CT Abdomen: Dilated colon with wall thickening and thumbprinting; no perforation; ascites present
Abdominal X-ray demonstrating toxic megacolon with markedly dilated transverse colon (>6 cm diameter), loss of haustral markings, and mucosal irregularity (thumbprinting). This is a surgical emergency.
Image Source: Case courtesy of Radiopaedia.org
Diagnosis
Toxic Megacolon Complicating Ulcerative Colitis
Clinical Correlation
Toxic megacolon is a life-threatening complication of IBD (and infectious colitis) defined by colonic dilation >6 cm with systemic toxicity. The inflammation extends transmurally, paralyzing colonic smooth muscle and causing dilation. The "paradoxical improvement" in diarrhea actually reflects colonic dysmotility, not healing. Criteria include colonic dilation plus at least 3 of: fever >38.5C, HR >120, WBC >10,500, and anemia. Risk of perforation is high, and mortality is significant. Contributing factors include electrolyte derangements (hypokalemia), opioid use, anticholinergics, and discontinuation of maintenance therapy.
Treatment
- Immediate ICU admission
- Aggressive IV fluid resuscitation, correct electrolytes (especially potassium)
- NPO, nasogastric decompression
- Broad-spectrum antibiotics (piperacillin-tazobactam) to cover translocation
- IV corticosteroids (hydrocortisone 100 mg every 8 hours)
- Avoid opioids, anticholinergics, and antidiarrheals
- Surgical consultation immediately - colectomy if no improvement in 24-72 hours, or earlier if perforation, peritonitis, or massive hemorrhage
- Serial abdominal X-rays to monitor for progression or perforation
- If responsive to medical therapy, transition to infliximab or other biologic for maintenance