Urolithiasis in children has a significant risk of recurrence and thus warrants a complete stone clearance. Many children have residual fragments (RF) in the kidney or ureter after ESWL or PCNL. Fragments 5 mm or less have high probability to pass spontaneously. The term clinically insignificant residual fragments (CIRF) have been established for these stones. However, this term is still controversial, as persisting fragments might be important risk factors for stone growth and recurrence. We evaluated the fate of small residual stone fragments (RF) identified up to 3 months following ESWL or PCNL in children.
Our study subjects included 40 children (42 renal units) with RF 5 mm or less 3 months following treatment using PCNL or ESWL for kidney stones. Median patient age was 6 years. Average initial stone burden was 18 mm. Mean follow-up was 28 months. Follow-up examinations consisted of radiographic studies, renal ultrasonography and urine culture. Outcomes such as spontaneous passage, growth of RF, symptomatic episodes or calculi recurrence were recorded.
Of the 42 renal units with RF 5 mm or less, 29 units (69 %) pass stone spontaneously, 8 units (19%) had an adverse clinical outcome (symptoms or RF growth) and 5 units (12%) were asymptomatic and had non-growing RF.
Most small RF in children passes spontaneously without adverse clinical outcome. A low incidence of stone growth has been found among children with RF. Based upon this observation, it is acceptable to use the term "clinically insignificant residual fragments" since most RF pass spontaneously. However, one fifth of the patients developed growth of RF or calculi recurrence, it is obvious that close follow-up is required as RF may act as a nidus for further stone formation.