How is acute cholecystitis diagnosed in a female over 40 years old presenting with sudden right upper quadrant (RUQ) pain, fever, and leukocytosis?

Diagnosis of Acute Cholecystitis

Acute cholecystitis cannot be diagnosed by a single clinical or laboratory finding; you must combine detailed history, physical examination, laboratory tests, and imaging—with ultrasound as the mandatory first-line imaging modality. 1

Clinical Features to Assess

History and Physical Examination

• Right upper quadrant (RUQ) pain or epigastric pain occurs in 72–93% of patients and is the most typical symptom 1
• Murphy's sign has a positive likelihood ratio of 2.8 but relatively low sensitivity (43–48% in some populations), so its absence does not exclude the diagnosis 1, 2
• Fever is present in only 36–74% of patients, and temperature >38°C occurs in just 6.4–10% of cases 1
• Vomiting or food intolerance occurs in 38–48% of patients 1
• Abdominal tenderness or guarding is found in approximately 65% of patients 1

Laboratory Findings

• Elevated C-reactive protein (CRP) is a key inflammatory marker; levels >75 mg/L support the diagnosis 1, 3
• Leukocytosis occurs in 41–59% of patients with acute cholecystitis 1, 3
• Elevated liver enzymes (AST, ALT) and bilirubin may be present but can be normal or only mildly elevated, particularly in early disease 4

Critical caveat: The absence of fever or leukocytosis does not exclude acute cholecystitis—one case series documented proven acute cholecystitis with normal WBC count and only mild enzyme elevations 4. Do not rely on laboratory values alone.

Imaging Strategy

First-Line: Ultrasound (Mandatory)

Ultrasound must be performed immediately as the first-line test, with sensitivity of 88% and specificity of 80%. 2 Look for at least 2 of the following findings to establish the diagnosis 2:

• Gallstones or sludge (present in 95% of acute calculous cholecystitis) 2, 5
• Gallbladder wall thickening >3–4 mm 2, 5, 6
• Pericholecystic fluid 1, 2, 5
• Gallbladder distension (anteroposterior diameter >4 cm) 5, 6
• Sonographic Murphy's sign (though insensitive if negative) 2, 6
• Stone impacted in gallbladder neck or cystic duct 2
• Wall hyperemia with elevated cystic artery velocities 6
• Tensile fundus sign (bulging fundus from increased intraluminal pressure) 6

Important pitfall: Overreliance on the sonographic Murphy sign results in surprisingly low diagnostic accuracy—its absence does not rule out acute cholecystitis 6.

Second-Line: Advanced Imaging When Ultrasound is Equivocal

If ultrasound is inconclusive or negative but clinical suspicion remains high:

• HIDA scan (hepatobiliary scintigraphy) is the preferred next test, with 97% sensitivity and 90% specificity for acute cholecystitis 2
• CT with IV contrast provides superior sensitivity (~92% vs ~79% for ultrasound) and is particularly useful for detecting complications like perforation, gangrenous changes, or pericholecystic abscesses 2, 4, 7
• MRI/MRCP offers precise visualization of biliary pathology when both ultrasound and CT are nondiagnostic 3, 2

Diagnostic Algorithm

1. Obtain detailed history focusing on: RUQ/epigastric pain, fever, vomiting, food intolerance 1
2. Perform physical examination for: Murphy's sign, RUQ tenderness, guarding 1
3. Order laboratory tests: CBC with differential, CRP, liver enzymes (AST, ALT), bilirubin, alkaline phosphatase 1, 3
4. Immediately obtain RUQ ultrasound looking for ≥2 diagnostic findings 2
5. If ultrasound is equivocal/negative but suspicion persists: proceed to HIDA scan as the next step 2
6. If HIDA is unavailable or contraindicated: obtain CT abdomen with IV contrast 2
7. Consider MRI/MRCP if both ultrasound and CT fail to clarify the diagnosis 3, 2

Special Considerations

Elderly Patients

• Atypical or absent pain occurs in 12–17% of elderly patients 1
• Positive Murphy's sign is present in only 43% of elderly patients 1
• Higher rates of leukocytosis and elevated CRP compared to younger patients, making these markers more reliable in this population 1
• The same diagnostic algorithm applies, but maintain higher suspicion even with atypical presentations 1

Acalculous Cholecystitis

• Occurs in critically ill patients with hypotensive episodes and prolonged gallbladder stasis 6
• Ultrasound findings are similar but without gallstones; look for wall thickening, pericholecystic fluid, and sludge 6

Gangrenous Cholecystitis

• May present with isolated leukocytosis without classic RUQ pain 7
• Has mortality rate up to 22% and perforation risk of 10% 7
• Requires urgent surgical intervention; CT is superior to ultrasound for detecting complications 7

Final emphasis: No single finding has sufficient diagnostic power to establish or exclude acute cholecystitis 1. The combination of clinical assessment, laboratory markers, and imaging—particularly ultrasound with at least 2 positive findings—provides the most reliable diagnosis 1, 2.