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Difficulty: MediumInterpreting Imaging Results

A 72-year-old man who is recovering from a right total hip arthroplasty performed 3 days ago develops progressive abdominal distension, mild diffuse abdominal pain, and nausea. He has not had a bowel movement since surgery, though he reports passing flatus. His medications include oxycodone, enoxaparin, and scheduled acetaminophen. Vital signs are temperature 37.1°C (98.8°F), blood pressure 130/80 mmHg, heart rate 88/min, and respiratory rate 16/min. Physical examination shows a massively distended, tympanic abdomen with hypoactive bowel sounds. There is no guarding, rigidity, or rebound tenderness. Laboratory results are unremarkable. A supine plain abdominal radiograph demonstrates diffuse dilation of the cecum, ascending colon, and transverse colon, with a maximum cecal diameter of 9 cm. There is a continuous column of gas extending down to the rectum with no discrete transition point. No free intraperitoneal air is visualized. Based on the interpretation of these imaging findings, which of the following is the most appropriate next step in management?

  1. Discontinuation of oxycodone, bowel rest, and intravenous fluidsAnswer
  2. B
    Administration of intravenous neostigmine
  3. C
    Endoscopic colonic decompression
  4. D
    Water-soluble contrast enema
  5. E
    Emergent exploratory laparotomy

Answer

The correct approach is the discontinuation of oxycodone, initiation of bowel rest, and administration of intravenous fluids.
This patient presents with postoperative adynamic ileus of the large bowel, known as acute colonic pseudo-obstruction (Ogilvie syndrome). The diagnosis is supported by the abdominal radiograph demonstrating diffuse colonic dilation with a continuous column of gas extending into the rectum, without a discrete transition point. The presence of rectal gas differentiates this condition from a mechanical large bowel obstruction, which would typically show a cut-off sign and an absence of distal gas. Because the maximum cecal diameter is 9 cm (less than the 10-12 cm threshold for high perforation risk) and there are no clinical or radiographic signs of ischemia or perforation, the initial management is strictly conservative. This includes bowel rest, intravenous fluid hydration, correction of any electrolyte abnormalities, and the discontinuation of medications that decrease bowel motility, such as the opioid analgesic oxycodone.

Step-by-Step Solution

1
Evaluate the clinical presentation.
The patient has postoperative abdominal distension and hypoactive bowel sounds while taking opioids, raising suspicion for an adynamic bowel state.
Identifying the clinical context helps narrow the differential diagnosis between functional ileus and mechanical obstruction.
2
Analyze the radiographic imaging findings.
The plain radiograph shows a 9 cm dilated cecum with a continuous column of gas reaching the rectum and no transition point.
The presence of distal colonic gas without a cut-off point confirms acute colonic pseudo-obstruction (Ogilvie syndrome) and effectively rules out a mechanical large bowel obstruction.
3
Determine the appropriate management strategy based on the imaging.
Conservative management is selected.
Because the cecal diameter is less than 12 cm (low immediate risk of perforation) and there is no free air, the standard initial treatment is supportive care and removal of exacerbating factors like opioids.

Key Concept

Acute colonic pseudo-obstruction (Ogilvie syndrome) is identified on plain radiography by diffuse colonic dilation with a continuous column of gas extending into the rectum. Initial management is conservative (bowel rest, IV fluids, discontinuing opioids) if the cecal diameter is less than 12 cm and no signs of perforation are present.
Estimated Time:1m 30s
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Interpreting Imaging Results

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