A 90-year-old man is brought in to ED from his nursing home with lethargy, confusion and fever.
There is limited history available, however on examination, he is very tender in the right upper quadrant.
An abdominal CT is performed
Describe and interpret the CT scan
This case demonstrates typical imaging features of cholelithiasis complicated by cholecystitis.
There are numerous small radio-opaque calculi in the gallbladder. There is thickening of the gallbladder wall (>3mm) with fat stranding in the gallbladder fossa.
Note, the majority of gallstones (approx. 80%) are non-radiodense and therefore they are usually difficult to identify on CT.
On this CT there is also oedema of the adjacent duodenum due to reactive inflammation.
There is preserved enhancement of the gallbladder wall, enhancement may be reduced or absent in gangrenous cholecystitis.
We look also for presence of extra luminal air locules (not seen in this case) adjacent to the gallbladder which would raise the suspicion of perforation.
As a comparison, note the normal appearance of the gallbladder with thin walls and clean pericholecystic fat in the study which was done one month prior, in the same patient.
Cholecystitis is due to acute inflammation of the gallbladder. It usually occurs secondary to cholelithiasis (95% of cases). Typical clinical presentation is with fever and raised WCC, and RUQ pain with a positive Murphy’s sign on examination.
Cholecystitis is a diagnosis confirmed with imaging. Generally, ultrasound is the preferred imaging modality. It is more sensitive than CT for the diagnosis of cholecystitis and does not carry the same radiation exposure.
While CT abdomen is not routinely required to diagnose acute cholecystitis, it is more helpful than USS in ruling out other aetiologies, and is more useful in assessing for complications of cholecystitis.
Complications to look for include;
- Gangrenous gall bladder or pericholecystic abscess – causing sepsis
- Perforation – presenting with peritonitis
- Emphysematous cholecystitis – abdominal crepitus
- Gallstone ileus – causing bowel obstruction
When CT is the imaging modality used, key CT features to look for in making the diagnosis of cholecystitis are;
- Distension of the gallbladder – this is usually the first stage in the series of events leading to inflammation from obstruction of bile flow
- Gall bladder wall thickening
- Mucosal hyperenhancement
- Adjacent fat stranding/fluid
- Gall bladder sludge
- Gallstones (although may be missed if isodense to bile)
This patient was managed with IV antibiotics (gentamicin and ampicillin) and cholecystectomy.
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Sydney-based Emergency Physician (MBBS, FACEM) working at Liverpool Hospital. Passionate about education, trainees and travel. Special interests include radiology, orthopaedics and trauma. Creator of the Sydney Emergency XRay interpretation day (SEXI).
Emergency Medicine Education Fellow at Liverpool Hospital NSW. MBBS (Hons) Monash University. Interests in indigenous health and medical education. When not in the emergency department, can most likely be found running up some mountain training for the next ultramarathon.