Question

70 year-old male recently treated for community-acquired pneumonia presents with bloody diarrhea, fever, and severe abdominal pain. Abdominal Xray is shown below. Diagnosis?  

Answer

Answer: Toxic Megacolon

Toxic megacolon (TM) is an acute colitis with segmental or total colonic dilation (>6cm) plus systemic toxicity.

Actual incidence is unknown, but it is believed that TM is rising because of increasing cases of Clostridium difficile and the aging population. 

The most common etiologies are ulcerative, chron, and pseudomembranous colitis, but other causes exist and can be categorized as:

• Inflammatory (e.g., ulcerative colitis, Behcet's disease, etc.)
• Infectious (e.g., Clostridium difficile, Salmonella, Shigella, CMV, etc.)
• Ischemia  
• Miscellaneous (chemotherapy, Kaposi sarcoma, etc.)

The diagnosis is made based on clinical evidence of colitis plus evidence of colonic dilation on abdominal XR (diameter > 6cm, loss of haustra, or free intraperitoneal air secondary to perforation) or CT scan (demonstrating dilation or perforation).

Treatment includes:

• Aggressive fluid resuscitation and vasopressors/inotropes.
• Broad-spectrum antibiotics
• NPO, NG tube for bowel decompression, and avoiding medications reducing GI motility (e.g., narcotics)
• Early surgical evaluation is required although definitive surgical care (including colectomy) may be delayed for up to 3 days while monitoring the response to conservative treatment.

References

Autenrieth, D et al. Toxic Megacolon Inflammatory Bowel Dis. 2011 Aug 29. 

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