Pathogenesis of gallbladder wall perforation: Madrazo, et al has implicated –

• Calculous obstruction of the cystic duct,
• Causing luminal distention, leading to vascular compromise of the gallbladder wall and
• Subsequent ischemia and necrosis, resulting in a perforation of the gallbladder.

Ultrasound is the initial, and many times the only, modality used to image the gallbladder. No sonographic signs that would suggest imminent perforation have been described and therefore all cases of acute cholecystitis that are being managed conservatively must be followed up till complete resolution. Perforation, when it occurs shows the following ultrasound features-

• The usual signs of acute cholecystitis,
• A discontinuity or defect in the gallbladder wall at the site of perforation.
• Serpiginous intraluminal membranes due to sloughed mucosal lining.
• One or more hypoechoic or complex heterogeneous masses adjacent to the gallbladder, representing peri-cholecystic fluid collections or abscesses.

A recent report by Konno, et al emphasizes the significance of color Doppler in detecting the defect in the gallbladder wall as a flow signal passing through the perforated site.

The case illustrated here shows irregular, linear echogenic material along the gallbladder wall, which raises a suspicion for sloughed mucosa. However, adherent or linear sludge can also create this appearance and pathologic proof is lacking in this case. No fluid collections were seen in the area around the gallbladder, so the ultrasound did not specifically suggest perforation but in the presence of a sloughed lining it should be considered a possibility.  A CT scan performed the following day, after the patient experienced another episode of severe right upper quadrant pain, showed the defects in the gallbladder wall due to perforation. Ultrasound and CT findings are almost comparable in the detection of perforation, although certain studies find CT to be superior.