Hydronephrosis is common during pregnancy and is often physiological; however, it may also result from true obstruction requiring intervention. Differentiating between physiological and obstructive hydronephrosis remains a clinical challenge using conventional ultrasound.

This prospective observational study aims to evaluate the diagnostic accuracy of renal cortical stiffness measured by shear wave elastography (SWE) in differentiating obstructive from physiological hydronephrosis in pregnant women. Participants presenting with hydronephrosis will undergo clinical assessment, laboratory investigations, and ultrasound evaluation including SWE measurements.

The diagnostic performance of SWE will be assessed using receiver operating characteristic (ROC) analysis, and optimal cut-off values will be determined. The study aims to provide a safe, non-invasive, and quantitative tool to improve diagnosis and guide management in pregnant patients with hydronephrosis.

This is a prospective observational diagnostic accuracy study conducted at Beni-Suef University Hospital from April 2026 to April 2027.

Pregnant women aged 18 years or older, at ≥12 weeks of gestation, presenting with loin pain and sonographic evidence of hydronephrosis will be included. Patients with chronic kidney disease, congenital renal anomalies, preeclampsia, or poor acoustic window will be excluded.

All participants will undergo clinical evaluation, laboratory investigations, and conventional ultrasound assessment including hydronephrosis grading and cortical thickness measurement. Renal cortical stiffness will be assessed using shear wave elastography (SWE). Measurements will be obtained with the patient in a semi-left lateral position, with the region of interest placed within the renal cortex at a depth of 1.5-3.5 cm. Ten valid measurements will be recorded for each kidney, and the median value will be used for analysis.

Measurements will be performed at baseline, with follow-up at 2-4 weeks, after any intervention (if applicable), and 6-8 weeks postpartum.

The reference standard for diagnosing obstructive hydronephrosis will be based on clinical course, need for intervention (e.g., ureteral stenting or nephrostomy), and postpartum resolution of hydronephrosis.

The primary outcome is the diagnostic accuracy of SWE, assessed by the area under the receiver operating characteristic (ROC) curve. Secondary outcomes include determination of optimal SWE cut-off values and correlation with hydronephrosis grade and cortical thickness.

Statistical analysis will include ROC curve analysis, calculation of sensitivity and specificity, logistic regression analysis, and assessment of reproducibility using intraclass correlation coefficient (ICC). A p-value <0.05 will be considered statistically significant.

• Inclusion Criteria:

  • Pregnant women ≥12 weeks gestation with Loin Pain.
  • Sonographic evidence of hydronephrosis.
  • Age ≥18 years.
  • Provided informed consent

• Exclusion Criteria:

  • Chronic kidney disease (CKD).
  • Congenital renal anomalies.
  • Pre-eclampsia
  • Poor acoustic window.
  • Contraindication to examination position.

pregnant women

Pregnant women aged 18 years or older presenting with loin pain and sonographic evidence of hydronephrosis at Beni-Suef University Hospital.