Luk A. et al., 2023: Endourological Options for Small (less than 2 cm) Lower Pole Stones - Does the Lower Pole Angle Matter?
Department of Urology, Freeman Hospital, Freeman Road, Newcastle-Upon-Tyne, UK.
Department of Urology, University Hospital Southampton, Tremona Road, Southampton, UK.
Abstract
Purpose of review: Small renal stones in the lower pole are often difficult to treat. The angle of the lower pole to the renal pelvis (lower pole angle) is a limiting factor to rendering the patient stone free. This review explores the definitions of the lower pole angle, the various treatment options available, and how outcomes are influenced by the angle.
Recent findings: It is clear the lower pole angle definition varies widely depending on described technique and imaging modality. However, it is clear that outcomes are worse with a steeper angle, especially for shock wave lithotripsy and retrograde intrarenal surgery (RIRS). Percutaneous nephrolithotomy has similar reported outcomes to RIRS, and there is limited evidence it may be superior for steeper angles over RIRS. Lower pole stones can be technically challenging and adequate assessment prior to choosing operative approach is key.
Curr Urol Rep. 2023 Apr 25. doi: 10.1007/s11934-023-01161-w. Online ahead of print. PMID: 37097431 Free article
Comments 1
When results of SWL are considered, it is important that the occurrence of residuals is determined more by the intrarenal anatomy than by the disintegration process itself. This article is a review of the lower pole anatomy and its influence on stone clearance following SWL, RIRS and PCNL.
One crucial measurement is IPA (infundibulo-pelvic angle) and several methods have been described how to measure IPA. Shortcomings mentioned are the lack of 3D-information and difficulties to measure IPA on NCCT-examinations. Although 3D-reconstruction of images can give more detailed information, such procedures are less convenient clinically.
Some years ago, we described a method based on measurements of the calyx height and calyx angle relative to a perpendicular line. By combining the calyx height and calyx direction a value of IPA was possible to calculate rather than to carry out the complex angle measurement. Its influence on the stone-free rate was shown [1].
Nevertheless, there are other factors that also determine fragment clearance such as calyx length, calyx width and patient mobility.
Reference
1. Leykamm L, Tiselius HG.Observations on intrarenal geometry of the lower-caliceal system in relation to clearance of stone fragments after extracorporeal shockwave lithotripsy.
J Endourol. 2007 Apr;21(4):386-92. doi: 10.1089/end.2006.0292
Hans-Göran Tiselius