Guler Y. et al., 2020: Factors affecting success in the treatment of proximal ureteral stones larger than 1 cm with extracorporeal shockwave lithotripsy in adult patients
Guler Y, Erbin A, Kafkasli A, Ozmerdiven G.
Department of Urology, Private Safa Hospital, Istanbul, Turkey.
Department of Urology, Haseki Traning and Research Hospital, Istanbul, Turkey.
Department of Urology, Dr. Lutfi Kirdar Kartal Traning and Research Hospital, Istanbul, Turkey.
Department of Urology, Istanbul Aydin University Medical Faculty, Istanbul, Turkey.
The aim of the study was to analyze the factors predicting success for the treatment of proximal ureteral stones larger than 1 cm with extracorporeal shockwave lithotripsy (SWL) in adult patients. Between January 2014 and December 2018, 480 adult patients in total underwent SWL and data were retrospectively evaluated. Patients with multiple ureteral stones, solitary kidney, congenital abnormality, skeletal system abnormality, history of previous urinary system surgery and SWL, renal insufficiency, patients who could not tolerate SWL and pediatric patients were excluded from the study. The remaining 415 patients were divided into two groups as success (Group 1, n = 307) and failure (Group 2, n = 108). The overall success rate was 73.9%. The values of stone size, Hounsfield Unit (HU), skin to stone distance (SSD), ureteral wall thickness (UWT), proximal ureter diameter, renal pelvis diameter, hydronephrosis grade, and duration of renal colic were significantly higher in Group 2 compared to Group 1. In binary logistic regression analyses, HU, UWT, and proximal ureter diameter were found to be independent predictors. HU, UWT, and proximal ureter diameter had sensitivity and specificity of 92-92%, 88-23%, and 87-46%, with cutoff values of 740 HU, 2.5 mm and 8.5 mm, respectively. The area under the curve values were 0.96, 0.97, and 0.96 for HU, UWT, and proximal ureter diameter, respectively. The CT-based parameters, including HU, UWT, and proximal ureter diameter are independent predictive factors with excellent accuracy for the treatment of proximal ureteral stones larger than 1 cm with SWL in adult patients. Based on these factors, SWL can be considered for proximal ureteral stones larger than 1 cm.
Urolithiasis. 2020 Apr 11. doi: 10.1007/s00240-020-01186-7. Online ahead of print. PMID: 32279108.
The authors of this article present their experience with SWL for treating stones with a diameter > 10 mm and located in the ureter. This retrospective analysis of 415 patients clearly identified patients who were successfully treated and those who were not.
I am not familiar with the Turkish lithotripter that was used, but my initial impression was that with the relatively low radiodensity of stones in Group 1, the average number of treatment session of 2.7 seems quite high.
In my mind the fundamental message is that irrespective of stone size or density early SWL of ureteral stones makes an important difference between success and failure.
The larger and harder stones in Group 2 with a mean clinical history of 2.5 months obviously were associated with pronounced impaction with ureteral oedema and obstruction (UWT 5.5±1.4 mm) and dilatation of the ureter (13.2 mm) These are values that should be compared with averages of 1.4±0.6 and 5.9± 1.5 mm, respectively.
It stands to reason that when large and hard stones are diagnosed in the proximal ureter and when there is a long history of renal colic (start of symptoms), URS seems to be the alternative that should be preferred instead of SWL. Alternatively, a therapeutic trick would have been to try to gently pass a stent beyond the stone and wait some time for SWL if that treatment modality nevertheless should be chosen.