extracorporeal Shock Wave Lithotripsy (ESWL) was performed in 87 gallstones from 47 patients with the piezoelectric lithotriptor to evaluate the fragmentation rate and average number of shock waves according to the characteristics of gallstones.
Sixty seven gallstones were classified as cholesterol stones (pure: 7, mixed: 42, and combination: 18), 15 stones as pigment stones (calcium bilirubinate: 7, and black pigment: 8), and five stones as rare stones on the basis of external
morphology
and
internal structure of cut surface of stones. Size of gallstones was ranged from 5 to 30 mm 9mean: 13.0±4.7mm). Sonography and plain radiography of each gallstone was performed to evaluate the characteristics of stones. Sonographic findings of
gallstones were classified into two types; type 1: surface echo with variable internal echo of gallstones and clean posterior acoustic shadow, type II: echo of whole gallstones with posterior acoustic shadow.
Sixty-six (95.7%) of 69 stones with sonographic type I were cholesterol stones and 15 (83.3%) of 18 stones with songoraphic type II were pigment stones (p<0.01). On plain radiographs, 35 stones were radiolucent and 52 stones had calcifications
with
variable patterns.
All 87 gallstones were fragmented by the piezoelectric lithotriptor. average number of shock waves for complete fragmentation of stones less than 2 cm and stones more than 2 cm was 1052.5 and 7454.2, respectively (p<0.01). Average number of shock
waves
for fragmentation of sonographic type I and II was 1845.3 and 147.4: respectively (p<0.01). Average number of shock waves for fragmentation of noncalcified stones and calcified stones were 1901.8 and 1219.5, respecitvely (p:0.260). However,
fragmentation of stones with diffuse calcification was easier than those of other types of calcification (p<0.05).
On the basis of our results, the most important variables determining the degree of fragmentation of gallstones using piezoelectric lithotriptor were not their chemical composition (p:0.093) or sonographic type (p:0.098) but their size (p<0.001)
and
calcification pattern (p:0.023).
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