Lamina muscularis propria thickness of renal pelvis predicts radiological outcome of surgical correction of ureteropelvic junction obstruction

Purpose: We examine if there is a relationship between the histopathology of the renal pelvis and postoperative radiological findings in children with ureteropelvic junction obstruction. Materials and Methods: The records of 220 patients who underwent pyeloplasty for isolated ureteropelvic junction obstruction between 1988 and 1996 were retrospectively reviewed, and 41 (42 kidneys) were identified who had adequate histological specimens and postoperative radiographic studies (ultrasonography and/or well tempered renogram) for examination. Histological features of the lamina muscularis propria from the renal pelvis were correlated with the radiographic outcome after pyeloplasty. Results: Lamina muscularis propria thickness of the renal pelvis correlated significantly with radiological improvement. All kidneys with renal pelvic lamina muscularis propria thickness less than 250μm. showed radiological improvement at 3 to 6 months postoperatively, those with thickness between 250 and 350 μm. had improvement at 9 months and those with lamina thickness greater than 350 μm. had a significantly worse outcome at all observation points. At 3 and 6 months postoperatively 16 of 30 (53%) and 23 of 34 (68%) children with radiological improvement had a mean lamina muscularis propria thickness of 252 ± 131.5 μm. and 263 ± 122.8 μm., respectively, while the remaining unimproved 14 and 12 patients had a mean thickness of 374 ± 64.3 μm. (p <0.01) 372 ± 66.1 μm. (p <0.05), respectively. Conclusions: The lamina muscularis propria thickness of the renal pelvic wall can provide insight to the expected time of postoperative improvement on radiological studies in children with ureteropelvic junction obstruction.