Editorial Comment on: Natural History of Conservatively Managed Ureteral Stones: Analysis of 6600 Patients by Yallappa et al.

Medical expulsive therapy (MET) is one of the most practiced treatment options worldwide for small ureteral calculi (<10 mm). It is recommended by major guidelines. ^1,2 Meta-analyses of multiple single-center randomized controlled trials (RCTs) that studied relatively small number of patients proved the efficacy of alpha adrenoreceptor blockers in promoting spontaneous passage of ureteral calculi in a shorter time than placebo. ^3,4 Recently, the role of MET was challenged by a multicenter RCT with large number of patients. ⁵ Therefore, it is important to know the spontaneous expulsion rate of small ureteral calculi (<10 mm) to better define the role of MET and identify patients who will benefit from this treatment.

In this study, Yallappa et al. ⁶ performed an extensive literature search for RCTs assessing the role MET for small ureteral calculi. They collected the data of the placebo groups in addition to patients' data included in other studies evaluating the natural history of ureteral calculi. The meta-analysis included 6600 patients from 70 studies. They have found an overall spontaneous expulsion rate of 64%. This result provides explanations for the controversies in MET literature. In the meta-analysis of Hollingsworth and colleagues, ³ the spontaneous expulsion rates were <60% in placebo groups of five out of six included studies. Therefore, the benefits of MET were obvious as they increased this rate to about 80% in five studies. In contrast, Pickard and colleagues ⁵ reported high spontaneous expulsion rate of 80% in the placebo group of their RCT. This can explain the reason for inability of MET to decrease the need for further treatment in comparison with placebo.

To resolve the controversy and identify patients who really need MET; Amer et al. ⁷ carried out a meta-analysis of 10 RCTs evaluating the role of MET that were adequately powered and had low risk of bias. They found that alpha-blockers were more beneficial for stones larger than 5 mm. ⁷ The results of subgroup analysis in the present systematic review also explain the reason of this finding as it elicited better spontaneous expulsion for stones <5 mm (75%). ⁶ Therefore, MET benefits were more obvious in ureteral stones >5 mm.

The results of the meta-analysis conducted by Amer et al. ⁷ reported a significant better stone expulsion rate in alpha-blockers group for distal ureteral stones. The present systematic review showed lower spontaneous expulsion rate of upper ureteral calculi (49%). ⁶ Combining these results can be a rationale of not choosing MET for treatment of upper ureteral calculi >5 mm. Recently, alpha-blockers were recommended as the MET for distal ureteral calculi >5 mm. ^2,8 Finally, this is an important systematic review that provides milestones in treatment of small ureteral calculi (<10 mm) by knowing the natural history and defining specific stone and anatomical characters to guide when to use MET.