Treatment was performed during a hospital stay of three days and two nights, and the subjects were only fasted before operation. Preoperative medication included diclofenac suppository, Atarax-P, atropine sulfate (i.m.), and glycerin enema (60 mL). When subjects complained of severe pain during operation, pentazocine (i.m.) was additionally administered. Renal stones were treated at a maximum energy level of 80%, while ureteral stones were treated at a level of 100%. Both renal and ureteral stones were treated with up to 3000 shock waves. Treatment effect was evaluated by kidney, ureter, and bladder (KUB) X-ray or intravenous pyelography at 1 and 3 months after operation, and was classified as stone-free status (absence of residual stones), effective (presence of residual stones 4 mm or smaller), inadequate (status other than the above), or ineffective (no stone fragmentation even after 2 treatment sessions of ESWL).

Treatment was completed if an effective or better response was demonstrated by KUB on the day after the operation. If stone fragmentation was found to be inadequate, a second ESWL session was performed after about 1 to 4 weeks. If any stone fragmentation was achieved, third and subsequent ESWL sessions were performed. Subjects with an inadequate or no response (ineffective) to ESWL underwent transurethral ureterolithotripsy (TUL) or percutaneous nephrolithotripsy (PNL). Subjects with urinary tract infection or with stones 20 mm or larger underwent placement of a double-J stent. During the procedure, subjects with renal or upper ureteral stones were placed in the ipsilateral supine position, those with middle ureteral stones in the ipsilateral prone position, and those with lower ureteral stones in the contralateral prone position (Figure ​(Figure1).1). Subjects with X-ray-negative stones underwent intravenous pyelography (IVP) and ureteral catheter insertion in combination with ESWL.

Fourteen subjects with X-ray-negative stones underwent intravenous pyelography (IVP) and ureteral catheter insertion in combination with ESWL. These patients had a stone-free status with only ESWL therapy.

Of the 25 cases in whom ESWL was ineffective, 8 cases were confirmed to be stone free three or more months after operation, while 7 cases with residual stones were followed up because hydronephrosis improved. Of the subjects with upper ureteral stones in whom ESWL was ineffective, 7 cases underwent TUL and 2 cases underwent PNL. One case with concomitant ureteral stenosis underwent holmium laser incision following stone fragmentation with TUL.

The chemical composition of stones could be determined in 128 cases. Calcium oxalate stones were the most frequent (68 cases), followed by mixed calcium oxalate and calcium phosphate stones (49 cases), and stones containing calcium were present in 126 cases.

Our hospital introduced the Sonolith vision (manufactured by EDAP) on March 1, 2004. This model belongs to third generation ESWL equipment. It uses electrical conduction electrodes as the shock wave generator, which generates shock waves in a highly electrical-conductive fluid. It provides accurate electrical discharge with high reproducibility, thus producing stable and constant energy. The use of a hydrophone pressure detector allows real-time display of the effective pressure of shock waves on a monitor. The generator is a shallow oval shape, and the output power can be adjusted to 100 different levels. The diameter of the shock-wave head is as large as 22 cm, and the consumptive electrodes can be used in four to five patients. This equipment has a focal depth of 130 mm and a focal size of 3 × 28 mm. The focal point is adjusted using an X-ray C-arm.

In 226 Japanese cases with renal or ureteral stones who were treated with ESWL in our hospital, the stone-free rate was 85.4% and the efficacy rate was 88.9%, showing similar results to those obtained by other researchers [2-5]. (Table ​(Table44).

With regard to lower ureteral stones, Hochreiter et al. [6] treated distal ureteral stones with the HM-3 lithotriptor manufactured by Dornier in 518 patients, and reported a stone-free rate of 97.3% and efficacy rate of 99.4%. Park et al. [7], however, reported that the stone-free rate was 55.6% for lower ureteral stones of 10 mm or larger. Pardalidis et al. [8] also reported that treatment was not so effective, with a stone-free rate of 84.6%. Ghalayini et al. [10] compared laser TUL with ESWL, and reported that laser TUL was significantly more effective than ESWL, with a stone-free rate of 97.5% vs. 81.5% three months after operation. Wu et al. [11] compared holmium yttrium-aluminum-garnet (YAG) laser TUL with ESWL in patients with upper ureteral stones, and reported that there was no significant difference in the treatment effect on stones 10 mm or smaller, with a stone-free rate of 91.1% for TUL vs. 85.3% for ESWL, while there was a significant difference in the treatment effect on stones 10 mm or larger, with a stone-free rate of 76.8% for TUL vs. 35.2% for ESWL. They stated that laser TUL was superior to ESWL for the treatment of stones 10 mm or larger. In our study, however, all subjects with stones 10 mm or larger achieved a stone-free status. This may be attributable to our new measures: we usually place patients in the contralateral prone position to potentiate the treatment effect on lower ureteral stones, in accordance with the report by Köse et al. [12], and before ultrasonography we also apply jelly in a thin layer to the skin surface and to the area on the treatment table around the spot in contact with the skin to avoid exposure to air, thereby reducing minute air bubbles generated from the skin surface and minimizing attenuation of shock waves. ESWL seems to be an effective first-line treatment also in subjects who have lower ureteral stones 10 mm or larger but do not wish to undergo TUL, but it is sometimes difficult to treat stones greater than 10 mm by ESWL monotherapy. So, it is necessary to perform ESWL and TUL combination therapy. In contrast, these subjects with X-ray-negative stones underwent intravenous pyelography (IVP) and ureteral catheter insertion in combination with ESWL. These patients of ours had a stone-free status with only ESWL therapy.

Madbouly et al. [13] recently reported that the treatment effect of ESWL with the Lithostar Multiline performed under general anesthesia was significantly greater when shock waves were delivered at a slow rate (60/min) than at a rapid rate (120/min), with an efficacy rate of 98.7% vs. 90.0%. Pace et al. [14] and Peterson et al. [15] also reported similar results. Thus, ESWL treatment should be performed at a slow rate in the future.