Category: Clinical Stones: Ureteroscopy
Introduction & Objective :
Worldwide, ureteroscopic surgeries are increasing. However, anatomical differences in the renal pelvicalyceal system make it difficult to describe the detailed ureteroscopic findings and share common information about the position of a stone or tumor, or the appropriate puncture site for a percutaneous approach. Currently, the nomenclature to describe the minor calyx is not unified. Thus, we analyzed a number of CT-urography images and proposed the nomenclature for each minor calyx and simple morphological classifications of the renal pelvis that are appropriate for endoscopic surgery.
We prospectively collected data on a total of 270 patients (540 kidneys) who underwent CT-urography. We then constructed three-dimensional images of the renal pelvis and examined their morphological classification.
Forty-eight kidneys were excluded from this study due to severe hydronephrosis or large renal cysts. The remaining 492 kidneys were included. We systematically categorized each minor calyx into five levels: Top, Upper, Middle, Lower, and Bottom. The Upper, Middle and Lower calyces were typically found in pairs: Anterior and Posterior. (Figure 1) The most common total number of minor calyces was eight (51%), followed by seven (30%). We also classified the form of the pelvis into Type I: single pelvis (58%) and Type II: divided pelvis (42%), according to the branch patterns of the renal pelvis. In Type II, the renal pelvis always bifurcated into the upper branch (Top and Upper) and lower branch (Middle, Lower, and Bottom). Type I was subclassified into three types: Type Ia (43%), the standard type; Type Ib (4%), with a wide pelvis; and Type Ic (11%), with a narrow pelvis. (Figure 2)
This anatomical classification can divide the renal pelvis into two major types (subdivided into four types) and name each minor calyx. This simple classification enables to share common intrarenal information, thus leading to the development of concrete treatment strategies.
Ryoji Takazawa– Chief doctor, Tokyo Metropolitan Ohtsuka Hospital, Toshima-ku, Tokyo, Japan
Sachi Kitayama– Toshima-ku, Tokyo, Japan
Yusuke Uchida– Toshima-ku, Tokyo, Japan
Satoshi Yoshida– Toshima-ku, Tokyo, Japan
Yusuke Kohno– Toshima-ku, Tokyo, Japan
Toshihiko Tsujii– Toshima-ku, Tokyo, Japan