Ureteropelvic junction obstruction is an important cause of hydronephrosis and potentially reversible renal functional impairment in children. Although open pyeloplasty is an effective standard treatment, the degree of postoperative renal functional recovery varies between patients.

This prospective observational cohort study will evaluate whether renal cortical shear wave elastography can predict renal functional recovery after open pyeloplasty in children with unilateral primary ureteropelvic junction obstruction. Renal cortical shear wave elastography will be assessed before surgery and during follow-up, and the change in elastography values will be compared with renal isotope findings after surgery.

The primary objective is to evaluate the predictive value of the change in renal cortical shear wave elastography from baseline to 3 months after surgery for isotope-defined renal functional recovery at 6 months after open pyeloplasty.

This is a prospective longitudinal observational cohort study conducted at the Department of Urology, Faculty of Medicine, Beni-Suef University.

The study will include children aged 6 months to 18 years with unilateral primary ureteropelvic junction obstruction who are scheduled for open dismembered pyeloplasty. Eligible children will undergo standard preoperative clinical assessment, laboratory investigations, renal ultrasonography, renal cortical shear wave elastography, and renal isotope assessment.

Preoperative imaging will include renal ultrasonography to assess hydronephrosis, anteroposterior pelvic diameter, and renal cortical thickness. Renal cortical shear wave elastography will be performed to measure cortical stiffness in the affected kidney. Renal isotope assessment will include diuretic renography for differential renal function and drainage assessment, with renal cortical scintigraphy when clinically indicated according to the approved protocol.

All included patients will undergo open dismembered pyeloplasty according to standard surgical principles. Postoperative follow-up will include clinical assessment, renal ultrasonography, and renal cortical shear wave elastography at 3 and 6 months. A repeat renal isotope study will be performed at 6 months after surgery to reassess differential renal function and drainage.

The primary outcome is the predictive performance of the change in renal cortical shear wave elastography from baseline to 3 months postoperatively for 6-month isotope-defined renal functional recovery after pyeloplasty. Secondary outcomes include the association between 3-month postoperative shear wave elastography and functional recovery, longitudinal changes in shear wave elastography, postoperative changes in differential renal function and drainage parameters, and improvement in ultrasonographic parameters after pyeloplasty.

Inclusion Criteria:

• Children aged 6 months to 18 years.
• Diagnosis of unilateral primary ureteropelvic junction obstruction.
• Planned for open dismembered pyeloplasty.
• Availability of preoperative renal ultrasonography, renal cortical shear wave elastography, and diuretic renography.
• Written informed consent obtained from parent or legal guardian.

Exclusion Criteria:

• Bilateral ureteropelvic junction obstruction.
• Secondary ureteropelvic junction obstruction.
• Previous ipsilateral upper urinary tract surgery.
• Associated major urinary tract anomalies likely to independently affect renal function, including vesicoureteral reflux, megaureter, duplex system, posterior urethral valves, or ectopic kidney.
• Active urinary tract infection at the time of assessment.
• Known intrinsic renal parenchymal disease unrelated to obstruction.
• Inability to obtain reliable shear wave elastography measurements.
• Incomplete planned follow-up.

Children aged 6 months to 18 years with unilateral primary ureteropelvic junction obstruction who are scheduled for open dismembered pyeloplasty at the Department of Urology, Faculty of Medicine, Beni-Suef University.

Individual participant data will not be shared. Only aggregated, de-identified study results will be reported. Individual-level pediatric clinical and imaging data will remain confidential and will be accessible only to the study investigators and authorized regulatory or ethics committee representatives if required.