Radiation-Free Versus Contrast-Based Imaging in Pelviureteric Junction Obstruction: A Head-to-Head Comparison of Serial Diuretic Ultrasound and Intravenous Urography

Abstract

Objective: To compare the diagnostic accuracy of serial diuretic ultrasound with intravenous urography for the diagnosis of pelviureteric junction obstruction, using operative findings as the reference standard.

Study Design, Place and Duration: This cross-sectional diagnostic accuracy study was carried out at Mooud Specialized Center, Tehran, Iran, from January 2021 to January 2022.

Materials and Methods: Sixty patients with clinical suspicion of pelviureteric junction obstruction were enrolled through consecutive sampling. Each patient underwent both serial diuretic ultrasound and intravenous urography. Diuretic ultrasound was performed after intravenous furosemide administration, and sequential anteroposterior pelvic diameter measurements were recorded. Intravenous urography was performed using standard departmental protocol. The results of both modalities were compared against operative findings and clinical follow-up. Sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy were calculated for each modality.

Results: Pelviureteric junction obstruction was confirmed in 27 (45.0%) patients on the reference standard. Serial diuretic ultrasound showed a sensitivity of 88.9%, specificity of 87.9%, and diagnostic accuracy of 88.3%. Intravenous urography demonstrated a sensitivity of 88.9%, specificity of 84.8%, and diagnostic accuracy of 86.7%. The kappa value between the two modalities was 0.499, indicating moderate agreement. No statistically significant difference was found between the two methods on the McNemar test (p=1.000).

Conclusion: Serial diuretic ultrasound performed comparably to intravenous urography in diagnosing pelviureteric junction obstruction and may be considered a practical alternative, particularly in settings where radiation exposure and contrast-related risks are of concern.