7 JOURNAL OF ENDOUROLOGY Volume 17, Number 1, February 2003 © Mary Ann Liebert, Inc. Erect and Supine Radiographs to Assess Effectiveness of SWL for Stones in a Caliceal Diverticulum or Dilated Calix SOLIEMAN BILGASEM, M.D., KENNETH. T. PACE, M.D., SARAH DYER, M.D., and R. JOHN D’A. HONEY, M.D. ABSTRACT Background and Purpose: There are patients who have been treated with shockwave lithotripsy (SWL) for stones in a caliceal diverticulum (CD) or a dilated calix in whom the degree of fragmentation is difficult to assess. The aim of this study was to see if adequate fragmentation could be confirmed by the demonstration of layering of fine fragments on an erect radiograph. Patients and Methods : Over a period of 9 months, 13 patients with stones in a CD or a dilated calix with a stenosed infundibulum were studied 2 weeks after SWL with erect and supine radiographs. Results: One of eight patients with a CD cleared all fragments. Two patients showed no change in the ap- pearance of the stone on either the supine or the erect film, and of the remaining five patients, three demon- strated layering of sand at the base of the CD. Five patients with a dilated calix and a narrow infundibulum were also studied: two of these patients became stone free, two demonstrated complete fragmentation with layering of the sand, and in one patient, a 4-mm fragment, hidden within the sand, was revealed only on the erect film. Conclusion: There are patients who have been treated with SWL for stones in a CD or a dilated calix in whom adequate fragmentation is difficult to demonstrate. An erect radiograph in these patients may demon- strate layering of the fragments to confirm fragmentation and obviate repeat SWL. INTRODUCTION S HOCKWAVE LITHOTRIPSY (SWL) is one treatment op- tion for stones located in a caliceal diverticulum (CD). It has been shown to be successful in relieving symptoms in 36% to 75% of such patients, 1–3 although clearance of stone frag- ments occurs in a significantly lower percentage of these pa- tients. 4,5 Success appears to depend on adequate fragmentation of the calculi, which may or may not clear from the CD de- pending on the location and the size of the communicationwith the collecting system. Adequate fragmentation of diverticular stones is often diffi- cult to demonstrate using a plain supine radiograph, as frag- ments confined to a CD may resemble a solid unfragmented stone, and patients may therefore be referred for unnecessary repeat SWL. Renal ultrasonography and spiral CT also fail to differentiate between fragmented and nonfragmented stones. The aim of this study was to determine the percentage of pa- tients in whom layering of the fine fragments at the base of the diverticulum can be demonstrated in an erect radiograph and the utility of positional films in discriminating between com- plete and incomplete stone fragmentation after SWL. PATIENTS AND METHODS Over a period of 9 months, patients treated with SWL for symptomatic stones located in a CD or in a dilated calix with a stenosed infundibulum, diagnosed on pretreatment intra- venous urography (IVU) (Fig. 1), were followed with both a supine and erect plain (KUB) film 2 weeks after SWL per- formed on a Dornier MFL 5000 lithotripter. Thirteen patients were included in the study: eight with a stone in a CD and five with a dilated calix with an infundibular width of #2 mm on IVU. Two patients had been referred to our lithotripsy unit for a second SWL treatment. Division of Urology, St. Michael’s Hospital, University of Toronto, Toronto, Ontario, Canada.