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Difficulty: EasyOrdering Imaging Studies

A 44-year-old woman comes to the emergency department due to a 3-hour history of severe, unrelenting pain in the right upper quadrant of her abdomen. She says the pain started shortly after she ate a high-fat meal for lunch. The pain radiates to her right shoulder, and she reports one episode of vomiting. She has experienced similar, milder episodes in the past that resolved on their own. Her temperature is 37.9°C (100.2°F), blood pressure is 132/86 mmHg, heart rate is 98/min, and respiratory rate is 16/min. On physical examination, the patient winces and abruptly halts her inspiration when the physician deeply palpates the right upper quadrant. Laboratory studies show a leukocyte count of 12,500/mm³ and normal serum liver aminotransferases, total bilirubin, and lipase levels. Which of the following is the most appropriate initial imaging study to establish the diagnosis?

  1. Right upper quadrant ultrasonographyAnswer
  2. B
    Computed tomography scan of the abdomen with intravenous contrast
  3. C
    Hepatobiliary iminodiacetic acid cholescintigraphy
  4. D
    Magnetic resonance cholangiopancreatography
  5. E
    Endoscopic retrograde cholangiopancreatography

Answer

Right upper quadrant ultrasonography is the most appropriate initial imaging study.
The correct answer is right upper quadrant ultrasonography. This patient's clinical presentation of postprandial right upper quadrant pain radiating to the right shoulder, fever, leukocytosis, and a positive Murphy sign strongly suggests acute cholecystitis. Ultrasonography is the established standard-of-care and the most appropriate initial imaging study for suspected biliary tract disease. It effectively identifies gallstones, gallbladder wall thickening, and pericholecystic fluid, and allows the clinician to elicit a sonographic Murphy sign. It is preferred over other modalities because it is non-invasive, avoids ionizing radiation, is cost-effective, and provides immediate bedside information.

Step-by-Step Solution

1
Analyze the clinical presentation and physical examination findings.
The patient presents with postprandial right upper quadrant pain radiating to the shoulder, fever, leukocytosis, and a positive Murphy sign (inspiratory arrest upon palpation).
These classic findings strongly suggest a diagnosis of acute cholecystitis.
2
Identify the standard-of-care initial diagnostic imaging modality for this suspected condition.
Right upper quadrant ultrasonography is the preferred first-line imaging test.
Ultrasonography is highly sensitive and specific for detecting gallstones, gallbladder wall thickening, pericholecystic fluid, and eliciting a sonographic Murphy sign, while avoiding ionizing radiation.

Key Concept

First-line imaging evaluation for suspected acute cholecystitis
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Ordering Imaging Studies

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