Observations on intrarenal geometry of the lower-caliceal system in relation to clearance of stone fragments after extracorporeal shockwave lithotripsy.
OBJECTIVE
To study the intrarenal geometry of the lower-caliceal system in patients with and without residual fragments after extracorporeal shockwave lithotripsy (SWL) and to formulate a summarizing mathematical expression of relevant variables.


METHODS
In a series of patients consecutively treated by SWL, we analyzed the geometric anatomy in 47 patients with (group R) and 47 without (group NR) residual fragments in long-term follow-up. A number of distances and angles previously described in the literature were measured, to which was added the distance between the stone-bearing calix and the vertex of the lower renal lip (CL) and the angle (delta) this line formed with a vertical line.


RESULTS
There were significant differences between the groups in terms of infundibular length (P = 0.009), CL (P = 0.0020), and lower-caliceal height, CH (P = 0.0004). The calix width and the various angles did not differ significantly between the groups. The quotient CH/CL was used to calculate cos delta, and a summarizing expression (Index LC) was given the form CH(2)/CL which equals CH x cos delta. This index was significantly different in groups R and NR (P = 0.0036). Approximately 4% of the patients in group NR, compared with 28 percent in group R, had Index LC values >25.


CONCLUSIONS
Index LC, as an expression of the geometry of the lower-caliceal system, might be useful for simple description of the lower-caliceal anatomy and supportive for decisions on the use of fragment clearance-facilitating procedures or the selection of a more invasive approach than SWL.
Leykamm
Lars
L
Department of Urology, Karolinska University Hospital (Huddinge), Sweden.
Tiselius
Hans-Göran
HG
D006801:Humans; D007669:Kidney Calculi / Q000628:therapy*; D007670:Kidney Calices / Q000033:anatomy & histology*; D008096:Lithotripsy / Q000379:methods*