INTACT STONES OR FRAGMENTS - POTENTIAL PITFALLS IN THE IMAGING OF PATIENTS AFTER BILIARY EXTRACORPOREAL SHOCK-WAVE LITHOTRIPSY

Ultrasound is used after extracorporeal shock wave lithotripsy of gallbladder stones to assess fragmentation. In many patients with apparently successful fragmentation, the posttreatment studies show an intraluminal, echogenic focus within the gallbladder, with posterior acoustic shadowing characteristic of an intact stone. Cholesterol gallstones were fragmented in vitro by means of lithotripsy, and the sonographic appearance of the fragmented stones was followed up over time to study factors that might affect the process. After lithotripsy, fragments settled and produced an echogenic focus with posterior shadowing indistinguishable from the appearance of an intact stone. These experimental observations led to the development of a clinical maneuver to overcome the diagnostic pitfalls posed by the reaggregation of stone fragments in situ. This rollover maneuver helps distinguish between intact stones and fragments, and prevents both diagnostic errors in follow-up and unnecessary retreatment.