Ultrasound Case 052

Image 1: Fanning through the gallbladder from fundus to the neck. There is echogenic sludge and debris layering within the gallbladder. Within the sludge a few hyperechoic calculi are seen. In the GB neck is large echogenic calculus with posterior acoustic shadowing. This is not mobile on rolling the patient into the left lateral decubitus position and is likely an impacted stone.

There is a very thin rim of subserosal oedema seen between the gallbladder and liver. There is also a small area of focal fatty sparing adjacent to the gallbladder.

The gallbladder was not markedly distended and only mildly tender to probe pressure. The wall measured 3mm across – the upper limit of normal.

There are several but not all of the features of cholecystitis.

Impacted Gallstone with probable early cholecystitis.

Acute calculus cholecystitis is generally diagnosed with ultrasound or CT scan. Gallstones and sludge maybe missed on CT, and CT cannot evaluate for tenderness. It may miss significant biliary disease.

Ultrasound is not perfect either. It is common to only have a few of the sonographic features of cholecystitis. In addition other pathology may mimic cholecystitis by causing gallbladder wall thickening, and the presence of gallstones does not necessarily imply cholecystitis.

Using Bayesian reasoning the astute clinician must synthesize a host of predictive variables including the history and clinical examination, laboratory investigations and sonographic findings to reach the correct diagnosis.

Sonographic features of cholecystitis:

• Cholelithiasis (unless acalculous)
• Tenderness to probe pressure directly over the GB – sonographic Murphy’s sign.
• Thickened gallbladder wall to > 3 mm (there are numerous other causes of GB wall thickening)
• Gallbladder distension > 9 cm in length and > 4 cm in width.
• Pericholecystic fluid (but ascites or free fluid from another pathology can cause the same).
• Subserosal gallbladder wall oedema.
• Hypervascularity of the gallbladder wall.