What is the significance and management of a positive Murphy sign in a patient?

Murphy Sign: Significance and Management

A positive Murphy sign is a significant diagnostic indicator for acute cholecystitis and should prompt immediate imaging with abdominal ultrasound, laboratory testing, and consideration for early surgical intervention within 72 hours of diagnosis. 1, 2

Definition and Clinical Significance

• Murphy sign: Pain elicited when a patient takes a deep breath while the examiner's fingers are pressed beneath the right costal margin over the gallbladder area
• Sonographic Murphy sign: Maximal tenderness elicited by direct pressure of the ultrasound transducer over the sonographically localized gallbladder

Diagnostic Value

• Positive likelihood ratio of 2.8 (95% CI 0.8-8.6) for acute cholecystitis 1
• When combined with gallstones on ultrasound:
  • 92.2% positive predictive value for acute cholecystitis 3
  • 99% positive predictive value for patients requiring cholecystectomy 3
• Negative predictive value of 95% when both Murphy sign is negative and no stones are seen 3

Important Caveats

• No single clinical finding has sufficient diagnostic power to establish or exclude acute cholecystitis 1
• Absence of Murphy sign in a patient with other signs of cholecystitis may suggest gangrenous cholecystitis (present in only 33% of gangrenous cases) 4
• Sensitivity of Murphy sign alone is limited (63%) but specificity is high (93.6%) 5

Recommended Diagnostic Approach

1. Initial Evaluation:

   • Assess for other clinical features: fever, right upper quadrant pain/tenderness, vomiting, food intolerance 1
   • Order laboratory tests: elevated C-reactive protein, elevated white blood cell count, liver function tests 1, 2

2. Imaging:

   • First-line: Abdominal ultrasound (investigation of choice) 1, 2

     • Look for: gallstones, gallbladder wall thickening (≥5mm), pericholecystic fluid, gallbladder distention, sonographic Murphy sign 2

   • If ultrasound inconclusive:

     • HIDA scan (97% sensitivity, 90% specificity) 2
     • CT with IV contrast (useful for complications or alternative diagnoses) 1, 2
     • MRCP (for suspected common bile duct stones) 1, 2

3. Diagnostic Accuracy Enhancement:

   • Combine Murphy sign, elevated neutrophil count, and ultrasound findings (cholelithiasis or cholecystitis) for improved diagnostic accuracy (sensitivity 74%, specificity 62%) 6

Management Algorithm

1. Uncomplicated Cholecystitis

• Early treatment (preferred): Laparoscopic/open cholecystectomy within 7-10 days of symptom onset 1

  • One-shot antibiotic prophylaxis
  • No post-operative antibiotics needed

• If surgery delayed:

  • Antibiotic therapy (≤7 days)
  • Plan for delayed cholecystectomy 1

2. Complicated Cholecystitis

• Laparoscopic cholecystectomy (open as alternative) 1
• Plus antibiotic therapy:
  • Immunocompetent patients: 4 days if source control adequate
  • Immunocompromised/critically ill: up to 7 days based on clinical condition 1

3. Antibiotic Selection

• Non-critically ill, immunocompetent patients:

  • Amoxicillin/Clavulanate 2g/0.2g q8h
  • If beta-lactam allergy: Eravacycline 1 mg/kg q12h or Tigecycline 100 mg loading dose then 50 mg q12h 1

• Critically ill or immunocompromised patients:

  • Piperacillin/tazobactam 6g/0.75g loading dose then 4g/0.5g q6h or 16g/2g continuous infusion
  • If beta-lactam allergy: Eravacycline 1 mg/kg q12h 1

Special Considerations

• Ongoing signs of infection beyond 7 days of antibiotic treatment warrant further diagnostic investigation 1
• Cholecystostomy may be considered for patients with multiple comorbidities unfit for surgery 1
• In older patients or those with atypical presentations, consider additional imaging beyond ultrasound 2
• Early surgical consultation is recommended even with equivocal physical findings due to risk of complications 2