[Extracorporeal shock-wave lithotripsy as treatment of lithiasis in horseshoe kidney]

Horseshoe kidney is the most frequent renal congenital anomaly, with an estimated general population prevalence of 1/400-500. This entity may be asymptomatic for the entire lifetime, or produce symptoms from associated complications such as lithiasis, hydronephrosis, or recurrent infections. The incidence of lithiasis varies between 20% and 80% of the patients. The treatment of lithiasis in this entity is controversial due to problems derived from the anatomy of the kidney and its drainage when stones are treated with external shock wave lithotripsy (ESWL). We tried to evaluate the efficacy of ESWL treatment and to establish the ideal conditions in which this technique may be considered treatment of choice.

A total of 25 patients were evaluated (17 males and 8 females). Patient age ranged from 8 to 75 year old. Three patients presented with bilateral lithiasis. 27 renal units were treated, 18 of which were left (66.7%) and 7 right. Stone size was measured in cm2 of surface. Lithiasis was located at the renal pelvis in 13 cases (48.1%), and lower calyx in 7 (25.9%). Four patients required JJ stent insertion. Mean number of shock waves per session was 3480 (range 1000-4000). Two Shock wave generators were used for treatment, the Dornier lithotripter S and the Dornier MFL-5000, with a range of 10-120 KV for the first one and 14-23 KV for the second. Follow up KUB X-rays were performed at 3, 6 and 12 months to evaluate fragmentation and elimination rates. In our series total fragmentation was 85.2%, and partial fragmentation (fragments > 6 mm) 14.8%. Elimination rates were satisfactory with 37.4% total elimination, and 48.1% partial elimination (Fragments < 6 mm). 14.8% of the patients had no elimination at all.

We consider ESWL the first therapeutic option for cases of lithiasis with a mean area 4 cm2 or less and pelvic location. In case of great lithiasic areas other therapeutic options should be considered (open surgery or percutaneous nephrolithotomy) either in monotherapy or complementary to ESWL.