What is the Critical age for the Improvement of Parenchymal Thickness after Pyeloplasty?

Purpose: The most important point in cases of ureteropelvic junction obstruction (UPJO) is to decide on the need and timing of surgical treatment. Renal damage may become irreversible as the duration of the obstruction is prolonged. Worsening of hydronephrosis and decrease in renal parenchymal thickness after pyeloplasty may herald an irreversible renal damage. It is important to know at what age this damage begins. In this study, we aimed to determine the relationship between the age of the patients at the time of pyeloplasty performed for UPJO and parenchymal recovery.

Materials and methods: In our study, 156 patients (mean age: 43.5 months) who underwent pyeloplasty with the diagnosis of UPJO between 2007 and 2019 were evaluated retrospectively. Demographic characteristics, ultrasonographic (USG) and nuclear renal scintigraphy findings, previous surgeries  ​of the patients  were recorded.

Results: Numerical variables were evaluated statistically, and the best cut-off point was determined. Parenchymal thickening was determined as the most important criterion in postoperative renal recovery which was more evident at early ages. Based on statistical assessments , the cut-off age for renal parenchymal recovery was determined as 38 months. While parenchymal recovery was inadequate after pyeloplasty performed in patients older than 38 months, the most significant improvement in renal functions was seen in children younger than 13 months of age.

Conclusion: Pyeloplasty should be performed in patients with UPJO before development of severe renal damage. Statistically, the best parameter to evaluate the recovery after pyeloplasty is the change in parenchymal thickness. With advancing age, it is impossible to reverse the obstructive nephropathy.