Korean J Urol.  2012 Jun;53(6):424-430.

Predictive Factors of the Outcome of Extracorporeal Shockwave Lithotripsy for Ureteral Stones

• Choi JW
• Song PH
• Kim HT

Abstract

PURPOSE
Extracorporeal Shock Wave Lithotripsy (ESWL) has shown successful outcomes for ureteral stones. We investigated predictive factors for failure of ESWL for treating ureteral stones.
MATERIALS AND METHODS
A total of 153 patients who underwent ESWL between July 2006 and July 2009 for ureteral stones diagnosed by non-enhanced spiral computed tomography were divided into two groups: (group A, stone size < or =10 mm; and group B, stone size >10 mm). The failure was defined as remnant stones >4 mm. We assessed age, sex, body mass index, stone size, laterality, location, skin-to-stone distance (SSD), Hounsfield unit, and the presence of secondary signs (hydronephrosis, renal enlargement, perinephric fat stranding, and tissue rim sign). We analyzed predictive factors by using logistic regression in each group.
RESULTS
The success rates were 90.2% and 68.6% in group A and B, respectively. In the univariate analysis of each group, stone size, SSD, and all secondary signs showed statistically significant differences in terms of the outcome of ESWL (p<0.05). In the multivariate logistic regression, stone size (odds ratio [OR], 50.005; 95% confidence interval [CI], 6.207 to 402.852) was an independent predictive factor in group A. The presence of perinephric fat standing (OR, 77.634; 95% CI, 1.349 to 446.558) and stone size (OR, 19.718; 95% CI, 1.600 to 243.005) were independent predictive factors in group B.
CONCLUSIONS
Stone size is an independent predictive factor influencing failure of ESWL for treating ureteral stones. In larger ureteral stones (>10 mm), the presence of perinephric fat stranding is also an independent predictive factor.

Keyword

Lithotripsy; Treatment outcome; Ureteral calculi

MeSH Terms

Body Mass Index
Humans
Lithotripsy
Logistic Models
Shock
Silver Sulfadiazine
Tomography, Spiral Computed
Treatment Outcome
Ureter
Ureteral Calculi
Silver Sulfadiazine

Figure

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  FIG. 1 The non-enhanced computed tomography scan images of secondary signs. (A) Hydronephrosis of the right kidney. (B) Renal enlargement and perinephric fat stranding of the left kidney (arrowhead). (C) Tissue rim sign of the left ureter (arrow).

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