Predictive value of calyx to parenchymal ratio for renal functional outcome after pyeloplasty in patients with pelviureteric junction obstruction

Abstract

Anderson–Hynes dismembered pyeloplasty is the standard surgical treatment for pelviureteric junction obstruction (PUJO), and postoperative assessment traditionally relies on anteroposterior pelvic diameter (APD) measured by ultrasonography and differential renal function (DRF) measured by DTPA diuretic renogram, both of which have recognized limitations. This prospective observational study aimed to evaluate the predictive value of calyx-to-parenchymal ratio (CPR) compared with APD and DRF in assessing renal functional outcomes after pyeloplasty. The study was conducted in the Pediatric Urology Division of the Department of Urology at Bangabandhu Sheikh Mujib Medical University from February 2023 to August 2024 and included 22 pediatric patients diagnosed with PUJO. Preoperative assessment included USG-based APD and CPR measurements and DTPA renogram for DRF evaluation, while postoperative assessments were performed at 3 and 6 months. The mean age of participants was 5.77 ± 5.3 years. DRF of the affected kidney improved significantly from 37.69 ± 10.57% preoperatively to 41.50 ± 8.94% at six months (p = 0.036), while the contralateral kidney showed a significant decline (p = 0.002). CPR showed a significant reduction from 8.37 ± 4.58 preoperatively to 2.96 ± 1.09 at six months (p = 0.001), whereas APD also decreased significantly (p = 0.001). A significant negative correlation was observed between CPR and DRF (r = −0.434, p = 0.043). Multinomial regression analysis identified change in CPR (ΔCPR) as a statistically significant predictor of renal functional outcome, while APD was not predictive. ROC analysis demonstrated optimal CPR change cut-off values with satisfactory sensitivity and specificity. The study concludes that ΔCPR is a reliable and significant predictor of renal functional recovery following pyeloplasty and may serve as a useful noninvasive follow-up parameter.