LOWER CALICEAL STONE CLEARANCE AFTER SHOCK-WAVE LITHOTRIPSY OR URETEROSCOPY - THE IMPACT OF LOWER POLE RADIOGRAPHIC ANATOMY

Purpose: We determine whether there is a significant relationship betw een the spatial anatomy of the lower pole, as seen on preoperative exc retory urography (IVP), and the outcome after shock wave lithotripsy o r ureteroscopy for a solitary lower pole caliceal stone 15 mm. or less . Materials and Methods: Between January 1992 and June 1996, 34 patien ts with 15 mm, or less solitary lower pole stone underwent ureteroscop y with intracorporeal lithotripsy (13) or extracorporeal shock wave li thotripsy (ESWL dagger) with a Dornier HM3 lithotriptor dagger (21). O n pretreatment IVP lower pole infundibular length and width, infundibu lopelvic angle of the stone bearing calix were measured. Stone size an d area were determined from an abdominal plain rr-ray. A plain x-ray o f the kidneys, ureters and bladder was obtained in all patients at a m edian followup of 12.3 and 8 months in the ureteroscopy and ESWL group s respectively. Results: After initial therapy the overall stone-free rate was 62 and 52% in the ureteroscopy and ESWL groups, respectively. Stone-free status after ESWL was significantly related to each anatom ical measurement. Infundibulopelvic angle 90 degrees or greater, and i nfundibular length less than 3 cm. and width greater than 5 mm, were e ach noted to correlate with an improved stone-free rate after ESWL. In contrast, the stone-free rate after ureteroscopy was not statisticall y significantly impacted by these anatomical features, although a clin ical stone-free trend was identified relating to a favorable infundibu lar length and infundibulopelvic angle. The infundibulopelvic angle wa s 90 degrees or greater in 4 stone-free patients (12% overall), includ ing 2 who underwent ureteroscopy and 2 who underwent ESWL. On the othe r hand, in 2 and 4 stone-free patients (18% overall) who underwent ure teroscopy and ESWL, respectively, favorable radiographic features cons isted of a short, wide but acutely angulated infundibulum with the inf undibulopelvic angle less than 90 degrees, and infundibular length les s than 3 cm. and width 5 mm. or greater. In contrast, in 4 and 6 patie nts (29% overall) who undenvent ureteroscopy and ESWL, respectively, a ll 3 radiographic features were unfavorable with the infundibulopelvic angle less than 90 degrees, and infundibular length greater than 3 cm . and width less than 5 mm. In these cases the stone-free rate was 50 and 17% after ureteroscopy and ESWL, respectively. Conclusions: The 3 major radiographic features of the lower pole calix (infundibulopelvic angle, and infundibular length and width) can be easily measured on s tandard IVP using a ruler and protractor. Each factor individually has a statistically significant-influence on stone clearance after ESWL. A wide infundibulopelvic angle or short infundibular length and broad infundibular width regardless of infundibulopelvic angle are significa nt favorable factors for stone clearance following ESWL. Conversely, t hese factors have a cumulatively negative effect on the stone clearanc e rate after ESWL when they are all unfavorable. In ureteroscopy spati al anatomy has less of a role in regard to stone clearance but it may have a negative impact when there is uniformly unfavorable anatomy.