DETERMINING HYDRONEPHROSIS IMPROVEMENT (SUCCESS) POST-PYELOPLASTY: THE HYDRONEPHROSIS OUTCOMES PREDICTION SCORE (HOPS) VERSUS THE PERCENT IMPROVEMENT OF RENAL PELVIS ANTERO-POSTERIOR DIAMETER (PI-APD)
Melissa McGrath, BASc, Yacoub Jafar, MD, Ziyad Alzahrani, MD, BRUNO LESLIE, MD, Luis H. Braga, MD, MSc, PhD.
McMaster University, Hamilton, ON, Canada.
Background: Determining success after pyeloplasty is still a matter of debate among clinicians, as hydronephrosis improvement post-surgery has not been objectively defined. We compared the hydronephrosis outcomes prediction (HOPS) score to the Percent Improvement of renal pelvis Antero-Posterior Diameter (PI-APD) in patients who underwent surgery for ureteropelvic junction obstruction (UPJO) to determine improvement of hydronephrosis and, consequently, pyeloplasty success.
Methods: Patients with prenatally detected UPJO who underwent pyeloplasty between 2013 and 2022 at a single tertiary pediatric center were reviewed. We excluded those with vesicoureteral reflux, megaureter), bilateral cases and other urological abnormalities. The following variables were collected at 3 different time points (baseline, at the time of surgical decision and 6 months postop): PI-APD, hydronephrosis severity (SFU, APD), percent of renal length difference and HOPS. Success post-pyeloplasty was defined as hydronephrosis improvement on a 6-month ultrasound showing either SFU grade I/II or APD <10mm. Descriptive statistics were calculated as appropriate, including mean (standard deviation) and medians (IQR) and chi-square analysis.
Results: Of 150 pyeloplasty patients, 106 (71%) were male, and 100 (67%) had left-sided obstruction. The median age at initial ultrasound (baseline) was 2.9 months (IQR 6), and the median age at surgery was 8 months (IQR 11). The mean HOPS was 9±2 at baseline and 11±1 immediately before surgery. At a median postoperative follow-up of 6 months, we observed that the HOPS had decreased to 5±2, compared to a PI-APD of 57%± 20%. Conclusion: The HOPS can be used to accurately determine hydronephrosis improvement post-pyeloplasty, as a median HOPS of 5 post-surgery corresponds to a median PI-APD post-surgery of 60%. As previously shown, PI-APD >40% has been considered as a clear marker of success post-pyeloplasty. Similarly, having a HOPS of 5 post-surgery can be considered as a surrogate for pyeloplasty success, as prior evidence showed that a HOPS ≤4 was associated with spontaneous resolution of hydronephrosis. We believe the HOPS is an objective and simplified way to quantify hydronephrosis improvement post-pyeloplasty, obviating the need for nuclear scans.
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