We commend Koh et al. [1] for conducting this study, but a few points need clarification. In the study, the authors mentioned that radiological evaluation of the patients included plain X-ray, ultrasonography and CT, but they have not clarified whether all these investigations were done for all the patients or whether they were mutually exclusive. Plain X-ray alone will not be able to detect stones as small as 2 mm (the range of stone size in the study was 2–20 mm).

The authors have mentioned in the results that conservative management was used in all patients. Even the title of the article states ‘Outcomes of long-term follow-up of patients with conservative management of asymptomatic renal calculi’. However, the authors do not mention what conservative treatment was given during the study period.

The authors have mentioned that 7.1% of patients needed some form of intervention. The interpretation of this data is difficult as the authors have not pre-defined the criteria for intervention in the ‘Patients and Methods’ section.

At the start of the study, the authors localised the stones as 43% in the lower pole, 26% in the mid pole and 31% in the upper pole. Did the authors encounter a situation that during follow-up, the stone was localised to a different calyx than the original position? As the authors have included calculi as small as 2 mm, this is a very likely situation. How have the authors interpreted this finding? Was it taken as a new stone formation following the passage of the previous calculus or was it interpreted as a migrated stone that was localised on previous radiological investigations?


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