passage in 29-98% of stones of < 5 mm diameter above the iliac vessels, and 71-98% of stones of < 5 mm diameter below the iliac vessels. For stones of 5-10 mm diameter, spontaneous passage occurred in 10-53% of proximal calculi and 25-53% of distal calculi. In a multivariate analysis of risk factors associated with spontaneous ureteric stone passage, Miller and Kane [2] found that smaller, more distal stones on the right side were more likely to spontaneously pass and require fewer surgical interventions. In a recent report by Coll et al. [3] spontaneous ureteric stone passage rates, regardless of size, were 48%, 60%, 75% and 79% for stones in the proximal, middle and distal ureter or at the vesico-ureteric junction, respectively.