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Although extracorporeal shock waves have been used to treat kidney stones for several years, little is known to their effect on developing tissue. In order to determine if lithotripsy has any negative effects on development, immature rabbits were used to study the relationship of extracorporeal shock waves to renal and skeletal growth. Rabbits in both the control and treatment groups had metallic clips placed surgically to demarcate the kidneys. Following unilateral kidney and femoral head treatment of the respective study groups with the Dornier Lithotripter Model HM-3, the rabbits were allowed to grow to maturity (six months). Plain radiographs were taken at three months. There was no significant difference between control and study groups when length of the kidneys or femurs, the diameter of the femoral heads, or the rabbits weights were compared. At six months of age, the rabbits were weighed, then sacrificed. The kidneys and femurs were removed. Comparisons between the control and study groups were then made for weight of the rabbit, weight and volume of the individual kidneys, femoral length, and femoral head diameter. Following these measurements sectioning and histologic examinations were done. In all parameters grossly and histologically, there was no statistically significant difference. It is concluded from this study that treatment with extracorporeal shock waves does not adversely affect overt rabbit renal or bone growth, making treatment of pediatric patients with ESWL appear safe in regard to these parameters. Future studies will be directed at confirming these findings in children.

From June 1985 to November 1986, 17 patients with calculi in horseshoe kidneys presented to our hospital for evaluation and possible treatment with extracorporeal shock wave lithotripsy. Of these patients 14 were treated with extracorporeal shock wave lithotripsy; the calculi in 2 could not be localized and focused at the F2 focal point, and 1 was asymptomatic and has been followed conservatively. Four patients required repeat extracorporeal shock wave lithotripsy. Adjunctive procedures included preoperative retrograde catheter placement (5 patients), postoperative percutaneous nephrostolithotomy (1), ureteroscopy for ureteral fragments (2) and placement of a double pigtail stent (1). Of 14 patients 11 (79 per cent) have been rendered free of fragments with extracorporeal shock wave lithotripsy and adjunctive measures as needed. We conclude that most patients with calculi in a horseshoe kidney can be managed primarily with extracorporeal shock wave lithotripsy.

Stone fragments that develop after extracorporeal shock-wave lithotripsy (ESWL) may lodge within the ureter. This column of fragments is referred to as a "steinstrasse" (plural, steinstrassen). We evaluated the first 1000 patients treated with ESWL at our institution to determine the frequency of steinstrasse formation, the clinical course of patients with steinstrassen, and the types of intervention, if any, required. Steinstrassen were seen in 20% of 1000 patients treated with ESWL. In 65% of the patients studied, the steinstrassen passed spontaneously. Of the remaining patients, all but 3% required treatment for ureteral obstruction. Seventy-five percent were treated urologically (ureteroscopy, ureteral catheterization), but 25% required radiologically directed intervention, either percutaneous nephrostomy or fluoroscopically monitored retrograde ureteral catheter/stent placement. Twenty-seven percent of our patients with persistent steinstrassen had silent obstruction. In view of the insidious manner in which kidney function may be jeopardized by steinstrassen, they should be managed with great circumspection. Radiologists dealing with steinstrassen should be skillful in both antegrade and retrograde methods of urinary tract intervention.

Routine follow-up urography demonstrated pseudoureteroceles caused by impacted calculus fragments in the distal portion of the ureter in five patients who had undergone extracorporeal shock wave lithotripsy of renal calculi 4-6 weeks before. Although all five patients showed some degree of obstruction at the time of follow-up urography, four were asymptomatic. Either small isolated fragments (two patients) or a column (steinstrasse) of fragments (three patients) was responsible for the abnormality. Two patients required further intervention to relieve the obstruction.