PANCE Blueprint GI and Nutrition (9%)

Toxic megacolon

Patient will present as → a patient brought into the emergency room appearing quite ill. He has a fever of 103.2°F, dry skin and oral mucosal membranes, and abdominal distention and tenderness. His medical history is significant for ulcerative colitis.

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
  • Pt will present with FEVER, markedly distended abdomen with peritonitis and shock
  • KUB shows dilated colon > 6 cm
  • Common in patients with Ulcerative Colitis and Crohn's disease

Abdominal plain-film radiography will show colonic dilation

  • KUB shows dilated colon > 6 cm
  • At least three of the following: Fever (>101.50F), Heart rate > 120/min, Neutrophilic leukocytosis (>10.5 x 109/L) and Anemia.

Decompression of the colon is required.

  • In some cases, colostomy or even complete colonic resection may be required
This patient has evidence of toxic megacolon involving the transverse colon and descending colon.

This patient has evidence of toxic megacolon involving the transverse colon and descending colon. Dilated colon > 6 cm

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.
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