Clinically Insignificant Residual Fragments: Is It an Appropriate Term in Children?

OBJECTIVE: To assess the outcome of clinically insignificant residual fragments (CIRFs) after shock wave lithotripsy (SWL) and percutaneous nephrolithotomy (PNL) in children. METHODS: Sixty-one children with CIRFs diagnosed by noncontrast computed tomography (NCCT) 3 months after SWL and 1 month after PNL with documented follow-up ≥6 months were included in the study. Children were evaluated by urinalysis, urine culture, plain abdominal radiography, and urinary ultrasonography or noncontrast computed tomography. Outcomes measured were fragment regrowth, spontaneous fragment passage, and secondary interventions. A clinically significant outcome was defined as the need for secondary intervention for development of complications or regrowth of the residual fragment (RF). RESULTS: The study included 42 boys and 19 girls with mean age of 6.2 years (range 1-14). After a median follow-up of 18 months, 16 children (26.2%) passed RF spontaneously. Regrowth of the RF was observed in 15 children (24.6%), and in 4 children (6.6%) the RF (of the same original size) slipped to the ureter and was treated by ureteroscopy. Therefore, a clinically significant outcome occurred in 31.2% of children with RF. Children with history of stone disease were more likely to develop clinical significance with time (HR, 4.38; 95% CI, 1.37-14; P = .013) CONCLUSION: The term CIRF is not appropriate for all children with post-SWL and -PNL fragments, as one-third of patients have had fragments that became clinically significant. History of stone disease was the only predictor of clinical significance.

Risk factors for formation of steinstrasse after extracorporeal shock wave lithotripsy for pediatric renal calculi: a multivariate analysis model.

OBJECTIVES: To define various stone, renal and therapy factors that could affect steinstrasse (SS) formation after extracorporeal shock wave lithotripsy (SWL) for pediatric kidney stones. Thus, SS could be anticipated and prophylactically avoided METHODS: From January 1999 through December 2012, 317 children underwent SWL with Dornier Lithotripter S for the treatment of renal stones. Univariate and multivariate statistical analyses of patients, stones and therapy characteristics in relation to the incidence of SS were performed to detect the factors that had a significant impact on SS formation. RESULTS: The overall incidence of SS was 8.5%. The steinstrasse was in the pelvic ureter in 74.1% of the cases, lumbar ureter in 18.5% and iliac ureter in 7.4%. Steinstrasse incidence significantly correlated with stone size, site and age of child. Steinstrasse was more common with increasing stone length and stones located in renal pelvis or upper calyx with the age below 4 years. A statistical model was constructed to estimate the risk of steinstrasse formation accurately. The equation for logistic regression is Z = -4.758 + B for age + B for size stone X length in mm + B for stone site. CONCLUSIONS: The stone size, site and age are the most important risk factors responsible for SS formation in children. Our regression analysis model can help with prospective identification of children who will be at risk of SS formation. Those children at high risk of SS formation should be closely monitored or treated by endoscopic maneuvers from the start.