[Renal morphology and urodynamic factors for renal stone formation]

Studies on the pathogenesis of urolithiasis have mainly focused on metabolic disorders. However, metabolic disorders alone are not sufficient to explain the problem. In the present study, morphological and urodynamic differences of the upper urinary tract on both the stone and normal side were examined. There were 35 cases of those who had experienced unilateral, recurrent, and/or multiple stone formation. 1. Morphologic study. Study of the pelvic-caliceal system (PCS) revealed significant differences in the following parameters on the stone side as compared with the normal side. The findings were: 1) the number of minor calices (papillaes), Np, was higher; 2) the number of major calices, Nm, was higher; 3) the number of branches, Nb, was higher; 4) the lower calyx radius, 1(2), was longer; 5) the total calyx area, Ac, was larger; 6) the renal pelvic area, Ar, was larger; 7) and the total area, At, was larger. 2. Urodynamic study. Additional study of the urodynamic factors revealed significant differences in the following parameters on the stone side as compared with the normal side. These findings include: 1) the peristaltic frequency in the upper third of the ureter was less; 2) the difference in peristaltic interval was longer and the rhythm of the peristaltic discharge was irregular. However, no significant difference in the contraction pressure was found except in the pelviureteral junction. After furosemide had been administered, the contraction pressure decreased while the peristaltic frequency increased on both sides. Furthermore, it was found that on the stone side the peristaltic interval decreased significantly as well as the rhythm of the peristaltic discharge becoming regular. The results of the two studies indicate that in the same individual the urine flow in the stone side as compared to the of the normal side is either stagnant or inconstant, thereby creating conditions conductive to the formation and growth of stones which become difficult to discharge owing to these same conditions. Therefore, morphological and urodynamic disorders of the upper urinary tract may be considered as factors contributing to stone formation. It appears that the diuretic action is an effective method for preventing stone recurrence and facilitating stone passage.