What predicts spontaneous passage of ≤ 1 cm ureteral stones in children?

Purpose: The aim of this study is to determine what factors predict spontaneous passage of ≤ 1 cm ureteral stones in children. Methods: Files of the patients diagnosed with a single ureteral stone on a given side between 2008 and 2017 were retrospectively reviewed. Patients with congenital obstructive uropathy, neurogenic bladder, vesicoureteral reflux and those with a stone diameter of > 1 cm were excluded. Detection of ureteral stones was done using ultrasonography (US) primarily, and computed tomography when US findings were inconclusive. Patients were treated either conservatively or surgically. Conservative treatment included adequate hydration and pain management whereas surgical treatment included ureteroscopic intervention. Apart from those who required urgent intervention, patients were referred for surgical treatment after 2–4 weeks of follow-up with no spontaneous passage. Factors analyzed for association of spontaneous passage included age, gender, type of hematuria, stone localization, laterality, presence of concomitant kidney stone, degree of hydronephrosis, stone size and stone composition. Results: A total of 70 patients (38 males, 32 females); median age 4.7 years had a ≤ 1 cm ureteral stone (median diameter 7 mm). US was able to diagnose the ureteric stone in 47 patients while computed tomography was required in 23 patients. Spontaneous passage was observed in 40 patients (57.1%). Median time for stone passage was 8 days (3–34 days). Stone size and presence of hematuria (macroscopic and microscopic combined) were factors associated with spontaneous passage and 6.7 mm was found to be the cut-off (AUC = 0.953; 95% CI 0.905–1.000; sensitivity 96.7%, specificity 82.5%, p < 0.001). Moreover, age, degree of hydronephrosis or stone location were not associated with spontaneous passage. Conclusion: Patients with a ureteric stone size < 6.7 mm can safely be followed conservatively, with a spontaneous passage rate of 82.5%. Type of Study Case series with no comparison group. Level of Evidence IV