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Ureteric stents compromise stone clearance after shockwave lithotripsy for ureteric stones: results of a matched‐pair analysis
Author(s) -
Argyropoulos Athanasios N.,
Tolley David A.
Publication year - 2009
Publication title -
bju international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.773
H-Index - 148
eISSN - 1464-410X
pISSN - 1464-4096
DOI - 10.1111/j.1464-410x.2008.07886.x
Subject(s) - medicine , ureter , mcnemar's test , extracorporeal shockwave lithotripsy , stent , ureteric stent , surgery , lithotripsy , ureteroscopy , laser lithotripsy , statistics , mathematics
OBJECTIVE To identify the effect of the presence of a ureteric stent on the outcome of extracorporeal shockwave lithotripsy (ESWL), by comparing patients with ureteric stones with matched‐pair analysis. PATIENTS AND METHODS Patients undergoing ESWL with the Sonolith Vision lithotripter (Technomed Medical Systems, Vaulx‐en‐Velin, France) were identified from our prospectively maintained database. Only adult patients with a solitary, radio‐opaque, previously untreated ureteric stone were considered for further analysis. A follow‐up of ≥3 months with a plain abdominal film was used to identify residual fragments. Patients were exactly matched for gender, side, location in the ureter and size (in two dimensions, within ±2 mm). If both diameters could not be matched exactly, the size was extended to ±1 mm and then to ±2 mm of both diameters. An effort was finally made to match patients by age. The treatment outcome in terms of stone‐free rates was assessed and compared using McNemar’s test. RESULTS In all, 45 patients with a ureteric stent in place during ESWL were identified. The only patient who could not be adequately matched was a 40‐year‐old man with an 8 × 3 mm stone in the upper ureter. The best/closest match for age was selected. Most stones were in the upper ureter (77%); the mean stone size was 8.5 and 8.6 mm, respectively, with no statistical differences between the groups for age and size of stones ( P = 0.41 and 0.86, Student’s t ‐test). In 12 pairs, only patients with no stent were stone‐free, compared to two pairs where the patient with a stent was stone‐free. Using McNemar’s test, the odds ratio was 6.0 (95% confidence interval 1.3–55.2) and the difference between the groups was statistically significant ( P = 0.016). CONCLUSION These results show that the presence of a stent is associated with a worse outcome after ESWL for ureteric stones. Ureteric stents should still be used in cases of obstruction, when there is a risk of sepsis, and in patients with intolerable pain or deteriorating renal function. However, their use in patients offered ESWL for ureteric stones should be considered with caution.