PANCE Blueprint GI and Nutrition (8%)

Toxic megacolon

Patient will present as → a 33-year-old male with a known history of ulcerative colitis presents to the emergency department with severe abdominal pain, diarrhea, and a fever of 103.2°F that began two days ago. He notes that his diarrhea has recently worsened, and he has been passing several bloody stools daily. He also reports significant abdominal distension. On examination, he is tachycardic and hypotensive, with a distended, tender abdomen and reduced bowel sounds. His white blood cell count is markedly elevated, and a plain abdominal X-ray reveals colonic dilation of 7.5 cm. You suspect toxic megacolon. He is admitted to the intensive care unit for close monitoring and immediate medical management. A surgical consult is obtained. Intravenous corticosteroids are started to reduce inflammation, and broad-spectrum antibiotics are initiated to cover secondary infections. Fluid resuscitation is given to correct dehydration and electrolyte imbalances.

Toxic megacolon is usually a complication of inflammatory bowel disease, such as ulcerative colitis and, more rarely, Crohn's disease, and of some infections of the colon, including Clostridium difficile infections, which have led to pseudomembranous colitis.

  • Life-threatening form of colon distention
  • Patients will present with FEVER, markedly distended abdomen with peritonitis and shock
  • KUB shows a dilated colon > 6 cm
  • Common in patients with Ulcerative Colitis and Crohn's disease

Toxic megacolon is diagnosed based on clinical signs of systemic toxicity combined with radiographic evidence of colonic dilatation (diameter >6 cm)

The most widely used criteria for the clinical diagnosis of toxic megacolon are:

  • Radiographic evidence of colonic distension
  • PLUS at least three of the following:
    • Fever >38ºC
    • Heart rate >120 beats/min
    • Neutrophilic leukocytosis >10,500/microL
    • Anemia
  • PLUS at least one of the following:
    • Dehydration
    • Altered sensorium
    • Electrolyte disturbances
    • Hypotension
Toxic Megacolon in Ulcerative Colitis

Toxic Megacolon seen in ulcerative colitis. The patient was then subjected to colectomy (removal of the whole colon).

Supportive therapy for all patients with toxic megacolon includes ICU monitoring, fluid resuscitation, broad-spectrum antibiotics, bowel rest, and surgical consultation

  • Bowel decompression with a nasogastric tube can be performed at the discretion of the treating clinician

Definitive Therapy for IBD-Related Toxic Megacolon:

    • IV glucocorticoid therapy for three days.
      • Infliximab (preferred) or cyclosporine (alternative for UC only) for three days if there is no response to glucocorticoids
      • Subtotal colectomy and ileostomy if the patient does not respond to medical treatment or develops toxic megacolon despite glucocorticoid, infliximab, or cyclosporine therapy

Definitive Therapy for C. difficile-Related Toxic Megacolon:

    • Antibiotic therapy targeted to C. difficile infection
    • Surgery indicated if colonic perforation, necrosis, ischemia, compartment syndrome, peritonitis, or end-organ failure, with options for total abdominal colectomy or diverting ileostomy with colonic lavage.

Question 1
A 45-year old woman being managed for ulcerative colitis, developed abdominal pain, vomiting, diarrhea, passage of blood and mucus per rectum and fever. On examination, she was pale, febrile (temp: 102.20C), moderately dehydrated, heart rate: 124bpm. There was abdominal distention and tenderness, bowel sounds were hypoactive. Lab results showed Hb: 9g/dl, WBC: 14 x 109/L, elevated CRP. Stool was negative for C. difficile. HIV status was negative. Abdominal radiograph showed dilated transverse colon of about 11 cm. What is the most likely diagnosis of this patient?
A
Hirschsprung’s disease
Hint:
presents with chronic constipation. Patients are not usually toxic except when intestinal perforation occurs.
B
Cytomegalovirus colitis
Hint:
Occurs in immunocompromised persons.
C
Toxic megacolon
D
Kaposi’s sarcoma
Hint:
Occurs in immunocompromised persons.
Question 1 Explanation: 
The hallmarks of toxic megacolon (toxic colitis) are nonobstructive colonic dilatation (>6 cm) and signs of systemic toxicity. It occurs following complication from causes of colitis e.g. ulcerative colitis as is the case in the index patient.
Question 2
Diagnostic criteria for Toxic megacolon includes all of the following except
A
Radiographic evidence of colonic dilatation (>6cm)
Hint:
See C for explanation
B
Fever (>101.50F)
Hint:
See C for explanation
C
Blood pressure > 150/90
D
Heart rate > 120/min
Hint:
See C for explanation
Question 2 Explanation: 
Diagnostic criteria for Toxic megacolon: A) Radiographic evidence of colonic dilatation (>6cm). B) At least three of the following: Fever (>101.50F), Heart rate > 120/min, Neutrophilic leukocytosis (>10.5 x 109/L), Anemia. C) In addition to the above, at least one of the following: Dehydration, Altered level of consciousness, electrolyte disturbances, hypotension. All other options are correct.
Question 3
Which of the following is not an etiology for toxic megacolon?
A
Ulcerative colitis
Hint:
See B for explanation
B
Pancreatitis
C
Crohn colitis
Hint:
See B for explanation
D
Pseudomembranous colitis
Hint:
See B for explanation
Question 3 Explanation: 
Pancreatitis is not a cause of toxic megacolon. All other options are predisposing factors.
Question 4
Which of the following is not a radiographic finding associated with toxic megacolon
A
Dilated colon (>6 cm).
Hint:
See C for explanation
B
Loss of colonic haustrations.
Hint:
See C for explanation
C
Frimann Dahl sign.
D
Segmental colonic parietal thinning.
Hint:
See C for explanation
Question 4 Explanation: 
Frimann Dahl’s sign is seen in sigmoid volvulus. All other options are seen toxic megacolon
Question 5
Initial resuscitation of a patient with toxic megacolon includes all of the following except
A
Placing of intravenous line for rehydration and electrolyte correction.
Hint:
See D for explanation
B
Administration of broad spectrum intravenous antibiotics.
Hint:
See D for explanation
C
Passage of a nasogastric tube for decompression.
Hint:
See D for explanation
D
Administration of an antidiarrheal agent.
Question 5 Explanation: 
All medications that may affect colonic motility (narcotics, antidiarrheals, and anticholinergic agents) should not be given to patients with toxic megacolon, or if patients were on them, the medications should be stopped.
There are 5 questions to complete.
List
Return
Shaded items are complete.
12345
Return

References: Merck Manual · UpToDate

Rectal prolapse (Prev Lesson)
(Next Lesson) Diarrhea (ReelDx + Lecture)
Back to PANCE Blueprint GI and Nutrition (8%)

NCCPA™ CONTENT BLUEPRINT