Utility of stone volume estimated by software algorithm in predicting success of medical expulsive therapy
Keywords:Nephrolithiasis; Nephrolithotomy, Percutaneous; Ureteroscopy; Health Care Costs; Health Resources
Introduction: We sought to assess the accuracy of using stone volume (SV) estimated with a software algorithm as a predictor for stone passage in a trial of medical expulsive therapy (MET).
Methods: We identified patients with ureteral stones discharged from the emergency department on MET. Patients with infection, non-ureteral stones, or needing immediate surgical intervention were excluded. For each stone, longest dimension (LD) was recorded, and SV was estimated by a computed tomography (CT)-based region-growing (RG) algorithm and standard ellipsoid formula (EF). Stone passage within 30 days was assessed via electronic chart and followup phone call.
Results: Fifty-one patients were included for analysis (53±16.7 years, 24% female). The mean LD was 4.85±2.02 mm. The mean SV was similar by EF and RG (0.051±0.057cm3 vs. 0.049±0.052 cm3, p=0.28). Thirty-three (65%) patients passed their stone, while 18 (35%) did not. The mean LD for passed stones vs. failed passage was 4.1±1.7 mm vs. 6.2±1.8 mm (p=0.0002); the mean EF volume was 0.028±0.035 cm3 vs. 0.093±0.066 cm3 (p=0.00007); and the mean volume by RG was 0.028±0.027 cm3 vs. 0.088±0.063 cm3 (p=0.00005).
Conclusions: The clinical utility of SV estimated by software algorithm as a predictor for success of MET has not previously been examined. We demonstrated that spontaneously passed stones had a significantly smaller volume than those requiring intervention. Further prospective studies are needed to validate these findings and establish volume thresholds for probability of stone passage.
How to Cite
You, the Author(s), assign your copyright in and to the Article to the Canadian Urological Association. This means that you may not, without the prior written permission of the CUA:
- Post the Article on any Web site
- Translate or authorize a translation of the Article
- Copy or otherwise reproduce the Article, in any format, beyond what is permitted under Canadian copyright law, or authorize others to do so
- Copy or otherwise reproduce portions of the Article, including tables and figures, beyond what is permitted under Canadian copyright law, or authorize others to do so.
The CUA encourages use for non-commercial educational purposes and will not unreasonably deny any such permission request.
You retain your moral rights in and to the Article. This means that the CUA may not assert its copyright in such a way that would negatively reflect on your reputation or your right to be associated with the Article.
The CUA also requires you to warrant the following:
- That you are the Author(s) and sole owner(s), that the Article is original and unpublished and that you have not previously assigned copyright or granted a licence to any other third party;
- That all individuals who have made a substantive contribution to the article are acknowledged;
- That the Article does not infringe any proprietary right of any third party and that you have received the permissions necessary to include the work of others in the Article; and
- That the Article does not libel or violate the privacy rights of any third party.