Gastroenterology · Acute Colonic Pseudo-Obstruction
The facts most likely to be tested
Ogilvie syndrome is defined as acute colonic pseudo-obstruction in the absence of a mechanical obstruction.
The condition is most commonly associated with recent surgery, trauma, or severe metabolic derangement.
Abdominal imaging reveals massive colonic dilation, typically involving the cecum and ascending colon.
A cecal diameter >10-12 cm on abdominal imaging significantly increases the risk of colonic perforation.
Initial management for patients without signs of peritonitis or perforation is conservative therapy including bowel rest, nasogastric decompression, and rectal tube placement.
Neostigmine is the first-line pharmacologic intervention for patients who fail conservative management, provided there are no contraindications like bradycardia or bronchospasm.
Colonoscopic decompression is indicated if pharmacologic therapy fails or is contraindicated, while surgical intervention is reserved for patients with evidence of ischemia or perforation.
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A 72-year-old male is hospitalized on postoperative day 4 following a total hip arthroplasty. He complains of progressive abdominal distension and obstipation. Physical examination reveals a tympanitic, distended abdomen without signs of peritonitis. An abdominal radiograph demonstrates massive dilation of the cecum and ascending colon measuring 13 cm, with no evidence of a transition point or mechanical obstruction. The patient is hemodynamically stable with a heart rate of 75 bpm.
What is the most appropriate next step in management?
Intravenous neostigmine administration
The patient has Ogilvie syndrome with a cecal diameter >12 cm, placing him at high risk for perforation; since he is hemodynamically stable and lacks peritonitis, neostigmine is the indicated next step.
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Etiology / Epidemiology
Occurs in hospitalized/post-surgical patients with metabolic derangements or narcotic use.
Clinical Manifestations
Presents as acute colonic pseudo-obstruction with massive abdominal distension and tympany.
Diagnosis
Abdominal CT is the gold standard to rule out mechanical obstruction; cecal diameter >12 cm is the critical threshold.
Treatment
Neostigmine is the first-line pharmacotherapy; avoid in bradycardia or bronchospasm.
Prognosis
High risk of cecal perforation if diameter exceeds 12 cm; requires serial imaging.
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Epidemiology & Etiology
Commonly seen in elderly patients following orthopedic/pelvic surgery or severe medical illness. Precipitating factors include electrolyte imbalances (hypokalemia/hypomagnesemia) and use of opioids or anticholinergics. It represents a functional failure of colonic motility without a mechanical block.
Pertinent Anatomy
The condition primarily affects the cecum and right colon. The cecum is the most dilated segment due to the Law of Laplace, making it the most vulnerable site for rupture.
Pathophysiology
The mechanism involves an imbalance in the autonomic nervous system with excessive sympathetic tone or decreased parasympathetic input. This leads to colonic dysmotility and gas accumulation. If left untreated, the resulting cecal wall tension leads to ischemia and perforation.
Clinical Manifestations
Patients present with acute colonic pseudo-obstruction characterized by progressive abdominal distension. Physical exam reveals a tympanitic abdomen with decreased bowel sounds. Peritoneal signs or fever suggest impending perforation or ischemia, which are surgical emergencies.
Diagnosis
Abdominal CT with contrast is the diagnostic test of choice to exclude mechanical obstruction. The most critical value is the cecal diameter; a measurement >12 cm significantly increases the risk of perforation and mandates aggressive intervention.
Treatment
Initial management includes bowel rest, nasogastric decompression, and correction of electrolytes. Neostigmine is the first-line pharmacological agent for patients failing conservative therapy. Contraindications include bradycardia, active bronchospasm, or mechanical obstruction. If medical therapy fails, colonoscopic decompression is indicated.
Prognosis
The primary concern is cecal perforation, which carries a high mortality rate. Patients require serial abdominal radiographs every 12-24 hours to monitor cecal diameter until resolution.
Differential Diagnosis
Mechanical bowel obstruction: presence of a transition point on CT
Toxic megacolon: associated with systemic toxicity and history of IBD/C. diff
Paralytic ileus: involves both small and large bowel dilation
Volvulus: shows coffee bean sign on imaging
Fecal impaction: rectal vault filled with stool on DRE