Regression of renal collecting system dilatation after pyeloplasty in children: evaluation of dynamics

Introduction. Pediatric pyeloplasty ensures a successful outcome in 83 – 97% cases. However, current lack of consensus regarding the definition of "success" related to results of pyeloplasty prevents development of a generally accepted standardised approach to postoperative care management. 
Objective. To study the dynamics in regression of renal collecting system (RCS) dilatation in patients with urteropelvic junction obstruction (UPJO) following pyeloplasty. 
Materials & methods. We have investigated dynamics in regression of RCS dilatation in UPJO-patients following pyeloplasty. An intrinsic UPJO cause was established in 55 (80%) patients, an extrinsic factor (crossing vessel) — in 14 (20%) cases. The patients underwent surgery involving laparoscopic access, no reducing resection of the renal pelvis was performed. In the pre- and postoperative periods, renal ultrasonography was carried out in the prone position without volemic load and with an empty bladder. Pelvic anterior-posterior diameter measured in the sagittal plane were then compared. In all cases, external RCS drainage technique was employed until restoration of urodynamics in the upper urinary tract according to the pyelomanometry data.
Results. In 3 months following pyeloplasty, a regression is noted in the RCS dilatation by 40%, after 6 months — by 53%, after 12 months –— by 64% of the initial value. In patients with intrinsic UPJO causes, after 3 months following pyeloplasty a regression is noted in the RCS dilatation by 34%, after 6 months –— by 42%, after 12 months — by 61% of the initial value; in patients with extrinsic PUJO factors, after 3 months the regression noted in RCS dilatation is 49%, after 6 months — 56%, after 12 months — 86%. 
Conclusion. Pre- and postoperative renal ultrasound in PUJO cases should be performed in the prone position without volemic load and with an empty bladder. In patients with confirmed restoration of UPJ patency after 12 months following surgery, a decrease in the RCS dilatation by 61% is noted among the patients with intrinsic PUJO causes and by 86% from pre-surgery values in children with extrinsic UPJO factors.

1. Lee RS, Cendron M, Kinnamon DD, Nguyen HT. Antenatal hydronephrosis as a predictor of postnatal outcome: a meta-analysis. Pediatrics. 2006;118(2):586-93. DOI: 10.1542/peds.2006-0120

2. Sizonov V.V. Diagnostics segment pyeloureteral obstruction in children. Urology Herald. 2016;(4):56-120. (In Russian). DOI: 10.21886/2308-6424-2016-0-4-56-120

3. Mesrobian HG, Mirza SP. Hydronephrosis: a view from the inside. Pediatr Clin North Am. 2012;59(4):839-51. DOI: 10.1016/j.pcl.2012.05.008

4. Chertin B, Pollack A, Koulikov D, Rabinowitz R, Hain D, Hadas-Halpren I, Farkas A. Conservative treatment of ureteropelvic junction obstruction in children with antenatal diagnosis of hydronephrosis: lessons learned after 16 years of follow-up. Eur Urol. 2006;49(4):734-8. DOI: 10.1016/j.eururo.2006.01.046

5. Bondarenko S.G., Kagantsov I.M., Sizonov V.V., Akramov N.R., Pirogov A.V., Sablin D.E., Surov R.V., Baranov Yu.V. Laparoscopic Pediatric Pyeloplasty: Trends in Regions of the Russian Federation. Urology Herald. 2020;8(1):5-13. (In Russian). DOI: 10.21886/2308-6424-2020-8-1-5-13

6. Dy GW, Hsi RS, Holt SK, Lendvay TS, Gore JL, Harper JD. National Trends in Secondary Procedures Following Pediatric Pyeloplasty. J Urol. 2016;195(4 Pt 2):1209-14. DOI: 10.1016/j.juro.2015.11.010

7. Hsi RS, Holt SK, Gore JL, Lendvay TS, Harper JD. National Trends in Followup Imaging after Pyeloplasty in Children in the United States. J Urol. 2015;194(3):777-82. DOI: 10.1016/j.juro.2015.03.123

8. Hopewell S, Loudon K, Clarke MJ, Oxman AD, Dickersin K. Publication bias in clinical trials due to statistical significance or direction of trial results. Cochrane Database Syst Rev. 2009;2009(1):MR000006. DOI: 10.1002/14651858.MR000006.pub3

9. Park K, Baek M, Cho SY, Choi H. Time course of hydronephrotic changes following unilateral pyeloplasty. J Pediatr Urol. 2013;9(6 Pt A):779-83. DOI: 10.1016/j.jpurol.2012.10.005

10. Romao RL, Farhat WA, Pippi Salle JL, Braga LH, Figueroa V, Bägli DJ, Koyle MA, Lorenzo AJ. Early postoperative ultrasound after open pyeloplasty in children with prenatal hydronephrosis helps identify low risk of recurrent obstruction. J Urol. 2012;188(6):2347-53. DOI: 10.1016/j.juro.2012.08.036

11. Fernández-Ibieta M, Nortes-Cano L, Guirao-Piñera MJ, Zambudio-Carmona G, Ruiz-Jiménez JI. Radiation-free monitoring in the long-term follow-up of pyeloplasty: Are ultrasound new parameters good enough to evaluate a successful procedure? J Pediatr Urol. 2016;12(4):230.e1-7. DOI: 10.1016/j.jpurol.2016.04.026

12. Värelä S, Omling E, Börjesson A, Salö M. Resolution of hydronephrosis after pyeloplasty in children. J Pediatr Urol. 2021;17(1):102.e1-102.e7. DOI: 10.1016/j.jpurol.2020.10.031

13. Rickard M, Braga LH, Oliveria JP, Romao R, Demaria J, Lorenzo AJ. Percent improvement in renal pelvis antero-posterior diameter (PI-APD): Prospective validation and further exploration of cut-off values that predict success after pediatric pyeloplasty supporting safe monitoring with ultrasound alone. J Pediatr Urol. 2016;12(4):228.e1-6. DOI: 10.1016/j.jpurol.2016.04.003

14. Carpenter CP, Tolley E, Tourville E, Sharadin C, Giel DW, Gleason JM. Hydronephrosis After Pyeloplasty: "Will It Go Away?". Urology. 2018;121:158-163. DOI: 10.1016/j.urology.2018.08.010

15. Babu R, Sai V. Pelvis/cortex ratio: an early marker of success following pyeloplasty in children. J Pediatr Urol. 2010;6(5):473-6. DOI: 10.1016/j.jpurol.2009.12.004

16. Walker MR, Babikian S, Ernest AJ, Koch TS, Lustik MB, Rooks VJ, McMann LP. Sonographic evaluation of hydronephrosis in the pediatric population: is well-tempered sonography necessary? J Ultrasound Med. 2015;34(4):655-62. DOI: 10.7863/ultra.34.4.655