A 30-year-old man comes to the emergency department with a 4-day history of progressively worsening abdominal pain and bloody diarrhea. He was started on mesalamine therapy 6 months ago after being diagnosed with ulcerative colitis but has been noncompliant with treatment. His temperature is 38.8 C (102 F), blood pressure is 100/70 mm Hg, and pulse is 130/min. The patient is lethargic and has dry mucous membranes. There is marked abdominal distension and tenderness without rebound or guarding. Rectal examination shows guaiac-positive, maroon-colored, liquid stool. Which of the following is the best next step in this patient's workup?

Question

A 30-year-old man comes to the emergency department with a 4-day history of progressively worsening abdominal pain and bloody diarrhea.  He was started on mesalamine therapy 6 months ago after being diagnosed with ulcerative colitis but has been noncompliant with treatment.  His temperature is 38.8 C (102 F), blood pressure is 100/70 mm Hg, and pulse is 130/min.  The patient is lethargic and has dry mucous membranes.  There is marked abdominal distension and tenderness without rebound or guarding.  Rectal examination shows guaiac-positive, maroon-colored, liquid stool.  Which of the following is the best next step in this patient's workup?

Quizplus · Accepted Answer

11ec160b_3961_ba34_9249_d537c37a7cfd_MD0001_00 This patient with abdominal pain/distension, bloody diarrhea, fever, and signs of shock (eg, hypotension, tachycardia) in the setting of untreated ulcerative colitis likely has toxic megacolon. This is a common life-threatening complication of inflammatory bowel disease and is seen more frequently in ulcerative colitis than in Crohn disease. Toxic megacolon can also be associated with Clostridium difficile infection and other forms of infectious colitis. Severe, occasionally transmural inflammation causes release of inflammatory mediators, bacterial products, and increased nitric oxide, which contribute to colonic smooth muscle paralysis. Rapid colonic distension ensues, thinning the intestinal wall and making it prone to perforation. Plain abdominal x-ray is the preferred diagnostic imaging study as it may show colonic dilation (as seen above) with multiple air-fluid levels (not seen in this image). Free air may also be visualized in the setting of intestinal rupture, which presents with generalized peritonitis (eg, abdominal rebound tenderness/guarding). (Choice A) Abdominal ultrasonography is not typically performed to diagnose toxic megacolon. It is usually obtained in patients with acute right upper quadrant abdominal pain (eg, due to cholecystitis, ascending cholangitis) or suspected nephrolithiasis. It is also helpful in the setting of acute abdominal trauma to identify intraperitoneal free fluid. (Choices B and C) Barium enema and colonoscopy are normally contraindicated in patients with suspected toxic megacolon as these may cause perforation. (Choice E) Small-bowel contrast studies can be useful in the evaluation of small-bowel obstruction (eg, abdominal pain/distension, nausea, vomiting). However, this patient's history of untreated ulcerative colitis and bloody diarrhea is more consistent with toxic megacolon, which involves the large intestine. Educational objective: Toxic megacolon is a well-recognized complication of ulcerative colitis. Patients typically present with abdominal pain/distension, bloody diarrhea, fever, and signs of shock. Plain abdominal x-ray is the preferred diagnostic imaging study. Barium contrast studies and colonoscopy are contraindicated due to the risk of perforation. __________ References: Toxic megacolon. (http://www.ncbi.nlm.nih.gov/pubmed/22009735) A new look at toxic megacolon: an update and review of incidence, etiology, pathogenesis, and management. (http://www.ncbi.nlm.nih.gov/pubmed/14638335)

A 30-Year-Old Man Comes to the Emergency Department with a 4-Day