Extracorporeal shock wave lithotripsy in ureteral and kidney malformations

Extracorporeal shock wave lithotripsy (SWL) has long been accepted worldwide in the treatment of kidney stone disease. Upper ureter calculi in ureteral and kidney malformations are rather frequent (10-25%). The aims of this retrospective study were to determine whether malformations might impair fragment expulsion.

From 1986 to 1995, 203 patients with ureteral and kidney malformations were treated and followed up for a minimum of 1 year to a maximum of 9 years. Malformations included: ureteropelvic junction stenosis, horseshoe kidney, renal malrotation, renal ectopia, duplicated ureter, nonobstructive megaureter, medullary sponge kidney and caliceal diverticula. As pretreatment workup, all patients underwent conventional studies prior to SWL treatment: X-rays, renal ultrasound, intravenous pyelography, routine blood tests and urinalysis. All examinations were repeated at regular intervals for the first 6 months. Patients with metabolic disorders were excluded from the study. We also excluded patients with a follow-up of under 1 year. We considered three groups of patients: (1) stone-free patients at plain X-rays and ultrasound; (2) >90% elimination, i.e. stone-free patients at plain X-rays and positive at ultrasound; (3) patients with residual fragments at plain X-rays and ultrasound.

96 (55%) patients were in group 1 (stone free), 40 (19%) were in group 2 (>90% elimination) and 67 (26%) were in group 3 (residual). Residual stones were more frequent in patients with medullary sponge kidney (82%). In patients with renal ectopia the residual stone rate accounted for only 13% of cases.

There is evidence that SWL should always be offered to patients with ureteral and kidney malformations. These patients should however be considered at high risk for recurrences and so they need to be carefully followed up.