Shear Wave Elastography for Evaluation of Hydronephrosis in Pregnancy

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.