WCE 2018: Anatomy of Horseshoe Kidneys and Kidneys with Duplex Collecting Systems: Study Applied to Endourology

Paris, France (UroToday.com) Throughout endourological practices around the world, congenital abnormalities of the kidneys present a significant challenge for the treatment of nephrolithiases, specifically extracorporeal shock wave lithotripsy (ESWL) or percutaneous nephrolithotomy (PCNL). Anomalies of the upper urinary tract can include aberrant location, orientation, and shape of the kidney, as well as abnormalities to the collecting system and blood supply. Dr. Francisco Sampalo from the State University of Rio de Janeiro in Brazil recognized this issue and set out to elucidate the academic urology community about the specific anatomy of these abnormal patients. Through this study, Dr. Sampalo and his team attempted to analyze the intrarenal collecting system anatomy of the horseshoe kidney and kidneys with complete duplication of the ureter. 

In order to properly study these kidneys, 7 three-dimensional polyester resin endocasts of the collecting system were obtained from 6 fresh adult cadavers (Figure 1). Of these cadavers, 4 had unilateral complete duplication of the ureter and 2 had a horseshoe kidney. Of note, the causes of death were not related to the urinary tract. Once the endocasts were successfully molded and harvested from the cadavers, the spatial distribution of the calyces and the infundibula diameters were analyzed. For kidneys with complete duplication of the ureter, the superior and inferior units were analyzed separately. 

For the three horseshoe kidneys, there was 1 major calyx in the superior pole, ranging from 5.45 to 10.51 mm. The middle pole had a range of 0 to 2 major calyces that ranged from 1.8 to 4.8 mm. Finally, the inferior pole had only 1 major calyx that ranged from 7.3 to 12.5 mm. The number of minor calyces for the superior, middle, and inferior poles were 3 to 4, 3 in all, and 2 to 4, respectively. For the four complete duplications of the ureter, there were a complete separation between the two units in all samples (Figure 1). In the superior unit, 2 major calyces were observed for all cases, ranging from 6.95 to 11.88 mm. The number or minor calyces varied from 4 to 6. The inferior unit had a variation of major calyces from 2 to 3, which ranged from 4.96 to 10.05 mm. The number of minor calyces in the inferior unit varied from 6 to 9. 

In his conclusory statements, Dr. Sampalo explained to his audience of the importance of the anterior position of the horseshoe kidney pelvis, the varied positions of the calices in relation to the kidney lateral margin, and the infundibula diameters. These anatomical features should be considered in patients with upper tract anomalies before endourologic procedures are carried out. 

Figure 1: Three dimensional polyester resin endocasts of the kidney collecting system. A, Horseshoe kidney. B, Complete duplication of the ureter. C, Normal collecting system.  

Presented by Dr. Francisco J.B. Sampalo 
Authors: Luciano A. Favorito, Ulisses G. Sobrinho, Francisco J.B. Sampalo
Affiliation: Urogenital Research Unit, State University of Rio de Janeiro, Brazil

Written by: Zachary Valley, Department of Urology, University of California-Irvine medical writer for UroToday at the 36th World Congress of Endourology (WCE) and SWL - September 20-23, 2018 Paris, France