[Evaluation of factors in fragment disappearance after extracorporeal shock wave lithotripsy for gallstones].

To identify which factors are important determinants of fragment disappearance after extracorporeal shock wave lithotripsy (ESWL), 67 cases in which gallstones were fragmented to under 3 mm in diameter were retrospectively analyzed using data obtained by cholescintigraphy, ERCP, ultrasonography, computed tomography, and abdominal radiography. Cholescintigraphic findings showed that in the fragment-free group, the gallbladder appearance time was significantly longer, the ejection fraction was significantly higher, and the gallbladder discharge volume was significantly larger compared with the residual fragments group (p < 0.05). In addition, there was no bile reflux in the fragment-free group, ERCP studies showed no difference between both groups in the diameter of the cystic duct or the maximum diameter of the common bile duct and the pancreatic duct. The disappearance rate of stones was significantly higher in patients with type I a or I b gallstones according to Tsuchiya's classification when compared with patients who had non-I a, I b stones (p < 0.01) or stones showing low CT density values. These results suggest that normal coordination between the gallbladder and the sphincter of Oddi is important for the complete disappearance of fragments after ESWL in addition to the qualitative features of the gallstones.