What is Cholecystitis
Cholecystitis is inflammation of the gallbladder, most commonly caused by obstruction of the cystic duct by gallstones (90-95% of cases), leading to gallbladder distension and inflammation that can be life-threatening if not promptly diagnosed and treated. 1
Pathophysiology and Types
- Acute calculous cholecystitis represents the most frequent complication of gallstone disease, developing in 1-3% of patients with symptomatic gallstones 1
- The obstruction can be from gallstones, biliary sludge, or in rare cases be acalculous (5-10% of cases), typically occurring in critically ill patients without gallstones 2, 3
- When obstruction occurs, it results in gallbladder distension and inflammation that may be initially aseptic but can progress to bacterial infection 3
Clinical Presentation
The typical presentation includes 1:
- Right upper quadrant abdominal pain (most common symptom)
- Fever
- Nausea and vomiting
- Anorexia
- Leukocytosis on laboratory testing
Important caveat: Clinical history, physical examination, and routine laboratory tests alone do not provide sufficient diagnostic certainty—imaging is essential for diagnosis 1. Some patients may present atypically without fever, leukocytosis, or classic Murphy's sign 4.
Diagnostic Approach
Initial Imaging
- Ultrasound is the first-choice investigation for suspected cholecystitis, with 96% accuracy for detecting gallstones 1
- Ultrasound findings include 1:
- Pericholecystic fluid
- Distended gallbladder
- Edematous/thickened gallbladder wall (>3mm)
- Gallstones
- Positive sonographic Murphy's sign (though this has relatively low specificity) 1
Advanced Imaging When Ultrasound is Equivocal
- Hepatobiliary scintigraphy (HIDA scan) is the gold standard diagnostic test when ultrasound is non-diagnostic, with 97% sensitivity and 90% specificity 1, 2
- MRI with MRCP can be helpful in difficult-to-examine patients and is superior to CT for biliary assessment 1
- CT with IV contrast can detect complications (emphysematous, gangrenous, perforated cholecystitis) and adjacent liver hyperemia, an early finding in acute cholecystitis 1
Chronic vs Acute Cholecystitis
- Chronic cholecystitis is associated with gallstones in 95% of cases and results from single or recurrent episodes of acute inflammation 1
- Chronic inflammation causes gallbladder wall thickening and fibrosis 1
- Diagnosis of chronic cholecystitis is difficult on imaging—the gallbladder may appear contracted or distended, and pericholecystic fluid is usually absent 1