Effect of skin-to-stone distance on shockwave lithotripsy success.
OBJECTIVE
We evaluated the effect of increased body habitus on stone-free rates after shockwave lithotripsy (SWL), determined by three reproducible skin-to-stone distances (SSDs) on CT.


METHODS
We retrospectively reviewed the records of 85 patients with preoperative CT scans available on Stentor Radiology Imaging who underwent SWL with the unmodified Dornier HM3 lithotripter from 2002 to 2007. SSDs were measured at the following angles: 0 degrees (vertical), 30 degrees, and 90 degrees (horizontal). Successful therapy was defined as stone free (residual fragments <2 mm) on follow-up imaging. Data were analyzed using descriptive statistics, Student t test, and the Fisher exact test.


RESULTS
Four hundred and eighty patients underwent SWL at our institution from 2002 to 2007; 85 patients (50.6% men, mean age 50.8 +/- 15.7 years, mean body mass index [BMI] 28.8 +/- 6.6 kg/m2) had preoperative CT scans available for review. On follow-up imaging (142.7 +/- 217.2 days), 49.4% of patients were stone free. Mean SSDs (vertical, 30 degrees, horizontal) in patients who were stone-free v those with residual stone were 104.3 +/- 26.2 mm v 102.6 +/- 29.9 mm (P = 0.79), 103.9 +/- 28.2 mm v 101.0 +/- 31.5 mm (P = 0.66), and 106.6 +/- 25.3 mm v 107.1 +/- 29.3 mm (P = 0.94), respectively.


CONCLUSIONS
Multiple variables have been shown to be associated with SWL success. In our sample of patients with preoperative CT scans, SSD was found to have no effect on SWL success.
Jacobs
Bruce L
BL
Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA. jacobsbl@upmc.edu
Smaldone
Marc C
MC
Smaldone
Arlene M
AM
Ricchiuti
Daniel J
DJ
Averch
Timothy D
TD
D005260:Female; D006801:Humans; D008096:Lithotripsy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012867:Skin; D014057:Tomography, X-Ray Computed; D014545:Urinary Calculi / Q000000981:diagnostic imaging / Q000473:pathology* / Q000628:therapy*