Evaluating Kidney Length as an Early Indicator for Surgical Decision-making in Congenital Ureteropelvic Junction Obstruction

Aim: Diagnosing ureteropelvic junction obstruction (UPJO) is challenging due to the lack of a definitive test.The "increase in hydronephrosis" is an important but ambiguous sign, so multiple sonographic parameters are used together for evaluation.We aimed to assess kidney length change as an early indicator of increasing hydronephrosis and investigated whether monitoring patients with kidney length nomograms can aid in its follow-up.Materials and Methods: This study included patients with high-grade hydronephrosis due to UPJO who had undergone at least three sonograms between 2012 and 2022.Kidney long-axis diameters in consecutive sonograms were plotted on a nomogram curve, and deviation from the individual's percentile was considered as an abrupt length increase.Results: A total of 128 patients (84 operated on and 44 managed conservatively) were included.In initial sonography, 23 patients in the pyeloplasty group and 13 patients in the non-obstructive dilatation (NOD) group were already above the 97th percentile.An abrupt increase in length was observed in 63 patients, with 57 (94%) in the pyeloplasty group and 6 (19%) in the NOD group.Regarding the timing of surgery, 33 patients underwent surgery at a median of 7 (3-11.5)months after the abrupt increase, as there was no significant change in either anteroposterior diameter (p=0.076) or parenchymal thickness (p=0.240) at that time. Conclusion:Our study revealed a notable abrupt increase in kidney length in most UPJO patients who underwent pyeloplasty.Our findings suggest the potential for an objective criterion using the change in kidney length in the decision for surgery.