A 26-year-old man comes to the emergency department due to 6 weeks of intermittent lower abdominal pain and cramps accompanied by rectal urgency, bloody diarrhea, nausea, and decreased appetite. His symptoms have become more severe over the past 2 days. The patient has never traveled outside the country and has not been prescribed antibiotics recently. Temperature is 38.5 C (101.3 F), blood pressure is 90/50 mm Hg, pulse is 130/min, and respirations are 15/min. The patient is ill appearing and lethargic. Bowel sounds are decreased. The abdomen is distended, tympanic to percussion, and diffusely tender to palpation; rebound tenderness and muscle rigidity are absent. Rectal examination shows marked tenderness and mucus mixed with blood in the vault. Laboratory results are as follows:
| Hemoglobin | 10.2 g/dL |
| Leukocytes | 31,600/mm3 |
| Platelets | 398,000/mm3 |
Intravenous fluids are started, with improvement of blood pressure to 104/58 mm Hg and pulse to 108/min. Which of the following is the most appropriate next step in management of this patient?
Toxic megacolon | |
Pathophysiology |
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Clinical features |
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Diagnosis |
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Treatment |
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IBD = inflammatory bowel disease. | |
This patient with 6 weeks of lower abdominal pain, bloody diarrhea, and fecal urgency likely has undiagnosed inflammatory bowel disease (IBD). However, for the past 2 days, he has had worsening symptoms, abdominal distension and tenderness, leukocytosis, and systemic toxicity (eg, fever, hypotension, tachycardia). This presentation is concerning for toxic megacolon (TM), which can complicate IBD, often early in the disease (eg, initial presentation).
The diagnosis of TM requires both manifestations of systemic toxicity and radiographic confirmation of colonic dilatation without evidence of mechanical obstruction. CT scan of the abdomen with intravenous and oral contrast can identify features typical of TM:
CT scan can also assess for complications of TM (eg, colonic perforation or necrosis) that may require surgery.
Nonoperative management of TM is often successful and includes supportive care (eg, intravenous fluids, electrolyte repletion), bowel rest and decompression (eg, nasogastric tube), broad-spectrum antibiotics, and treatment of the underlying etiology. For TM due to IBD, intravenous glucocorticoids are first-line therapy; sulfasalazine is not used to treat TM and is initiated only after its resolution (Choice G).
(Choices A and B) Colonoscopy with biopsies may help distinguish between ulcerative colitis and Crohn disease based on gross findings or microscopic analysis and is usually one of first tests conducted in the workup of suspected IBD. Barium enema may help visualize strictures, fistulae, or mucosal ulceration in patients with IBD. However, in the presence of a dilated, inflamed colon (eg, TM), instillation of contrast (eg, enema) or air (eg, colonoscopy) can cause perforation; therefore, these studies are contraindicated in this patient unless imaging excludes TM or, if TM is confirmed, until the patient has already begun responding to treatment (eg, less pain and fewer bloody bowel movements with glucocorticoids).
(Choice D) Indications for emergency surgery in TM include peritonitis on examination and colonic perforation or necrosis on imaging. This patient has no signs (eg, rebound tenderness, rigidity) of peritonitis and can undergo imaging (eg, abdominal CT scan) as the next step to determine whether a radiographic surgical indication (eg, perforation, necrosis) is present or if nonoperative management is appropriate.
(Choice E) Opioids should be avoided in patients with TM because they slow colonic motility; this can worsen colonic dilation and precipitate perforation.
(Choice F) Parasites (eg, Entamoeba histolytica), for which the stool sample tests, can cause diarrhea; however, they typically do not cause systemic toxicity and, in the absence of a travel history, are much less likely than other causes.
Educational objective:
Diagnosis of toxic megacolon requires radiographic evidence (eg, abdominal CT scan) of colonic dilation >6 cm, along with manifestations of systemic toxicity (eg, fever, leukocytosis, hemodynamic instability).