Correct!
4. It occurs in the absence of an anatomic lesion that obstructs the flow of intestinal contents

Acute colonic pseudo-obstruction (Ogilvie's syndrome) is a disorder characterized by gross dilatation of the cecum and right hemicolon (although occasionally extending to the rectum). The approximate risk of spontaneous perforation is 3 percent, with an attendant mortality rate of 50 percent (1).

In a review of 400 cases, the most common associations were: trauma (nonoperative) 11%, infection (pneumonia, sepsis most common) 10%, cardiac (myocardial infarction, heart failure) 10%, obstetric or gynecologic disease 10%, abdominal/pelvic surgery 9%, neurological (Parkinson disease, spinal cord injury, multiple sclerosis, Alzheimer disease) 9%, orthopedic surgery 7%, miscellaneous medical conditions (metabolic, cancer, respiratory failure, renal failure) 32%, and miscellaneous surgical conditions (urologic, thoracic, neurosurgery) 12% (2).

In the literature, Cesarean section (even in the absence of bowel injury), normal vaginal delivery and spinal anesthesia are associated with acute colonic pseudo-obstruction. It also occurs as a rare complication during the post-operative period of cardiac surgery, occurring in 0.06% of patients in one series (3). An increasingly recognized association of acute colonic pseudo-obstruction is chemotherapy. Vincristine, all transretinoic acid and methotrexate are most commonly associated (4,5).  

The pathogenesis of acute colonic pseudo-obstruction is unknown. There is no proposed mechanism to explain colonic dilation in those patients without obvious involvement of the parasympathetic nerves.

Case continued:
Gastroenterology was consulted for urgent decompression. However, he was deemed a high risk for perforation given the severity of colonic dilatation. A rectal tube was placed and a large amount of air and loose stool was evacuated.

What is the role of pharmacologic therapy in patients with acute colonic pseudo-obstruction? (Click on the correct answer to proceed to the next panel)

  1. Erythromycin binds to motilin receptors in the intestine and stimulates smooth muscle relaxation
  2. Neostigmine, an acetylcholinesterase inhibitor, may be effective in producing rapid colonic decompression
  3. Pharmacologic therapy should only be attempted if colonic decompression fails
  4. There is good evidence that methylnaltrexone in the setting of post-operative acute colonic pseudo-obstruction is efficacious

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