The incidence of lower‐pole nephrolithiasis — increasing or not?

Abstract

Objective To determine if the incidence of lower‐pole nephrolithiasis is increasing. Methods A previously published meta‐analysis of trends in the location of stones in the kidney, using data from 1984 to 1992, determined the percentage of lower pole stones in 26 722 kidney stones treated by extracorporeal shockwave lithotripsy (ESWL). We performed prospective studies on all patients treated by ESWL for a single renal stone (not manipulated from the ureter) in two organizations; at Lithotripters Inc., 47 303 stones were treated with ESWL by 1000 urologists in private practice from 1989 to 1995. At the Midwest Urologic Stone Unit, 9357 stones were treated with ESWL by 200 urologists in private practice from 1987 to 1995. The distribution of stones in both samples was compared with that reported earlier. Results The meta‐analysis for stone location trends from the previously published article suggested that the percentage of kidney stones in the lower pole at ESWL increased erratically from 1984 to 1989 but was then stable for 3 years. The Lithotripters Inc. sample showed an essentially constant incidence from 28% in 1990 to 30% in 1995, and the Midwest Urologic Stone Unit sample showed an essentially constant incidence from 35% in 1988 to 36% in 1995. Conclusion The incidence of lower pole nephrolithiasis has remained stable from 1990.

Treatment of Renal Stones by Extracorporeal Shockwave Lithotripsy

“…This distribution has not changed during the last decades [89]. The overall results of ESWL for the management of calyceal calculi depend significantly on the localization and size of the stone [8, 13, 49, 50, 51](tables 6–8).…”

Lower Pole Midsize (1–2 cm) Calyceal Stones: Outcome Analysis of 56 Cases

“…Cass et al [6] reported an incidence of 30–36% stones treated with SWL was located in LP calyx. In general, it is recognized that small-sized calculi <1 cm are treated successfully with SWL while for larger ones >2 cm the method of choice is PNL.…”

“…In general, it is recognized that small-sized calculi <1 cm are treated successfully with SWL while for larger ones >2 cm the method of choice is PNL. Stones in the range of 1–2 cm represent an area of ongoing controversy regarding the respective roles of SWL, PNL and ureteroscopy [5,6]. …”

Renal Anatomical Factors for the Lower Calyceal Stone Formation

“…Stagnation and retention of crystals in the inferior calyceal system due to gravity is accused for lower pole calculi. Cass et al reported that 25-35% of calyceal calculi are localized in the inferior calyceal system [10]. ESWL is the first choice therapy for the problematic lower pole stones and the same anatomical area is evaluated in many studies that examines the effects of anatomical factors on the stone clearance after ESWL.…”