Spectrum of severe Cholecystitis: Empyema / Suppurative / gangrenous / perforated

The spectrum of severe Cholecystitis: Empyema / Suppurative / gangrenous/perforated

Pathogenesis & Imaging of Severe Acute cholecystitis:

It is a state of obstruction to the flow of bile from the gallbladder into the CBD. This leads to gallbladder distension and local inflammation & called as "Acute cholecystitis".

The most common cause is blockage of cystic duct is due to sludge or calculus.

Natural History:

1. Empyema of the gallbladder: There is bacterial overgrowth in the obstructed system leading to infection and pus formation. It is also called as suppurative cholecystitis

Imaging: Ultrasound - echogenic contents

CT Scan: High attenuation contents

2. Emphysematous cholecystitis: Infection due to gas-forming organism

Imaging:

Imaging: Ultrasound - dirty shadowing due to air

CT Scan: gas bubble in the lumen or wall

3. Gangrenous Cholecystitis: due to distension, there is venous congestion & pressure/ischemic necrosis of the mucosa.

Imaging:

Imaging: Ultrasound - striated thickening, which is irregular and associated

- pericholecystic collections

CT Scan: Mucosal interruption and non enhancement

4. Perforation

Imaging: Defect in the wall with associated collection

Differential Diagnosis:

1. Mucocele / Hydrops of the gallbladder: Distended gallbladder due to chronic obstruction and filled with mucoid material. It is sterile and non-infected.

Imaging: clear contents and over distended (4 cm in transverse and 10 cm in longitudinal). No acute signs

2. Pseudo wall thickening of the gallbladder:

- Viral infections (dengue / infectious mononucleosis)

- Cirrhosis

- Contracted gallbladder

Imaging: Mucosal is intact. The wall is thickened or edematous. Quite often, the lumen is collapsed. On ultrasound striations are seen.