What is the significance of a positive Murphy sign in diagnosing gallbladder disease?

Significance of a Positive Murphy Sign in Diagnosing Gallbladder Disease

A positive Murphy sign is a useful but insufficient diagnostic finding for acute cholecystitis, with a positive likelihood ratio of approximately 2.8 (95% CI: 0.8-8.6), and should always be used in combination with other clinical, laboratory, and imaging findings for accurate diagnosis of gallbladder disease. 1

Definition and Mechanism

• Murphy's sign is the arrest of inspiration during deep palpation of the right upper quadrant due to pain when the inflamed gallbladder comes in contact with the examiner's fingers 1
• The sonographic Murphy sign is a variation performed during ultrasound examination, defined as focal tenderness precisely over the sonographically localized gallbladder 1, 2

Diagnostic Value

Strengths

• Among clinical signs, Murphy's sign has one of the better diagnostic performances for acute cholecystitis compared to other physical examination findings 2
• When combined with gallstones on ultrasound, the positive predictive value increases significantly to 92.2% 3
• A negative Murphy sign combined with absence of gallstones on ultrasound has an excellent negative predictive value of 95.0% for excluding acute cholecystitis 3

Limitations

• The sonographic Murphy sign has relatively low specificity for acute cholecystitis 2
• Its absence is unreliable as a negative predictor if the patient has received pain medication prior to examination 2, 1
• Used alone, Murphy's sign has insufficient diagnostic power to establish or exclude acute cholecystitis 2
• Studies have shown varying diagnostic accuracy:
  • One study found sensitivity of 63% and specificity of 93.6% 4
  • Another study reported sensitivity of 86% but poor specificity of 35% 5

Optimal Diagnostic Approach

The World Society of Emergency Surgery strongly recommends:

1. Never rely on a single clinical or laboratory finding (including Murphy's sign) for diagnosing acute cholecystitis 2

2. Use a combination approach including:

   • Clinical features: fever, right upper quadrant pain/tenderness, vomiting, food intolerance
   • Laboratory tests: elevated C-reactive protein, elevated white blood cell count
   • Imaging: ultrasound findings suggestive of gallbladder inflammation 2, 1

3. Ultrasound is the first-line imaging modality for suspected gallbladder disease:

   • Look for gallstones, gallbladder wall thickening, pericholecystic fluid, and sonographic Murphy sign 2, 1
   • The combination of positive sonographic Murphy sign, elevated neutrophil count, and ultrasound showing cholelithiasis or cholecystitis improves diagnostic accuracy 6

Clinical Pearls and Pitfalls

• Murphy's sign may be falsely negative in patients who have received analgesics prior to examination 2, 1
• The sign may be positive in conditions other than acute cholecystitis, leading to false positives 5
• In critically ill patients, gallbladder abnormalities are common even in the absence of acute cholecystitis, making interpretation more challenging 2
• While cholescintigraphy has higher sensitivity (97%) and specificity (90%) for acute cholecystitis, ultrasound remains the initial test of choice due to shorter study time, ability to evaluate morphology, and identification of alternative diagnoses 2

When used as part of a comprehensive diagnostic approach rather than in isolation, Murphy's sign provides valuable information that contributes to the accurate diagnosis of gallbladder disease and guides appropriate management decisions.