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Difficulty: HardInterpreting Imaging Results

An on-call physician is summoned to the surgical step-down unit to evaluate an 81-year-old male who underwent a left total hip arthroplasty three days ago. The patient has been receiving intravenous hydromorphone for postoperative pain control. He complains of progressive abdominal bloating and cramping over the past 36 hours and reports no bowel movements or flatus since the surgery. His medical history is significant for chronic constipation, hypertension, and Parkinson disease. Vital signs demonstrate a heart rate of 105/min, blood pressure of 135/85 mm Hg, and temperature of 37.2°C (99.0°F). On physical examination, the abdomen is markedly distended and tympanic to percussion. There is mild, diffuse tenderness to deep palpation, but no guarding, rigidity, or rebound tenderness is appreciated. Laboratory results reveal a leukocyte count of 9,500/mm³. An anteroposterior supine abdominal radiograph demonstrates a massive, featureless, ahaustral loop of bowel resembling a bent inner tube. The apex of this dilated loop projects toward the right upper quadrant. There is a paucity of gas in the distal rectum, and no free intraperitoneal air is visualized.

Based on the interpretation of these radiographic findings and the clinical presentation, which of the following is the most appropriate initial step in management?

  1. Therapeutic flexible sigmoidoscopyAnswer
  2. B
    Intravenous administration of neostigmine
  3. C
    Emergent open surgical exploration
  4. D
    Computed tomography of the abdomen and pelvis with intravenous contrast
  5. E
    Surgical detorsion and right hemicolectomy

Answer

The most appropriate initial step in management is therapeutic flexible sigmoidoscopy to evaluate and detorse the sigmoid volvulus.
The correct intervention is therapeutic flexible sigmoidoscopy. The patient's plain radiograph demonstrates classic features of a sigmoid volvulus: a massively dilated, ahaustral loop of bowel resembling a 'bent inner tube' or 'coffee bean' that originates in the left lower quadrant/pelvis and points toward the right upper quadrant. In the absence of clinical signs indicating bowel necrosis or perforation (such as fever, peritonitis, leukocytosis, or free air on imaging), the gold standard initial management is endoscopic detorsion and decompression using a flexible sigmoidoscope.

Step-by-Step Solution

1
Analyze the clinical vignette for risk factors and presentation.
The patient is an elderly male with chronic constipation, Parkinson disease, and recent surgery with opioid use, presenting with signs of large bowel obstruction.
Identifying the patient profile helps establish a pretest probability for specific causes of colonic obstruction.
2
Interpret the described radiographic findings.
The radiograph reveals a massive, ahaustral, 'bent inner tube' loop projecting from the pelvis toward the right upper quadrant, pathognomonic for a sigmoid volvulus.
Imaging interpretation is required to differentiate between mechanical volvulus and generalized colonic pseudo-obstruction (Ogilvie syndrome).
3
Determine the appropriate management sequence based on the imaging diagnosis and patient stability.
Because there are no signs of peritonitis, perforation, or ischemia, non-operative endoscopic detorsion is the standard of care.
Avoiding unnecessary surgery or advanced imaging minimizes morbidity in a hemodynamically stable patient with an already confirmed diagnosis.

Key Concept

Uncomplicated sigmoid volvulus is diagnosed radiographically by an ahaustral, U-shaped bowel loop pointing toward the right upper quadrant (coffee bean sign) and is initially managed with endoscopic detorsion.
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Interpreting Imaging Results

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