Ultrasound and 99mTc-DMSA Scan Versus Voiding Cystourethrography in Diagnosis of Vesicoureteral Reflux in Children

Abstract

Background: Early detection of vesicoureteral reflux (VUR) is crucial to prevent potential complications such as recurrent urinary tract infections and kidney damage. Noninvasive diagnostic alternatives to voiding cystourethrography (VCUG), such as ultrasound (US) and 99mTc-DMSA scan, offer effective and safe methods for identifying VUR without exposing children to ionizing radiation. This investigation aimed to evaluate the efficacy of US and 99mTc-DMSA scan in detecting VUR compared with VCUG among children with urinary tract infection (UTI).

Methods: In this observational study, we included 540 hospitalized children with UTI in Aliasghar Children`s Hospital between April 2017 and May 2019. US and VCUG were performed on all patients, with 99mTc-DMSA administered to some to detect VUR. Sensitivity, specificity, positive and negative predictive values, overall accuracy, and kappa agreement were calculated to evaluate ultrasound efficacy in predicting VUR based on VCUG-confirmed existence or nonexistence of VUR.

Results: Out of 540 patients, VCUG identified VUR in 143 cases, with 90 (63%) classified as grades III to V. US results were abnormal in 97 of the 143 patients (67.8%) confirmed to have VUR via VCUG, while the 99mTc-DMSA scan showed abnormalities in 41 out of 69 (59%) cases detected by VCUG. The sensitivity and negative predictive value (NPV) of the 99mTc-DMSA scan for diagnosing VUR were recorded at 59.42% and 46.59%, respectively. For ultrasound, the overall accuracy was 61.30%, with sensitivity at 67.83%, specificity at 58.94%, NPV at 37.31%, and positive predictive value (PPV) at 83.57%. In children with high-grade VUR (grades III-V) as determined by VCUG, the sensitivity, specificity, and NPV for ultrasound were found to be 80%, 58.2%, and 93.60%, respectively. However, when both US and 99mTc-DMSA scan results were utilized for detecting high-grade VUR, the sensitivity, specificity, and NPV were calculated to be 92%, 42.30%, and 93.20%, respectively.

Conclusion: While both US and the 99mTcDMSA scan are not fully reliable in detecting all grades of VUR individually, integration of US and ^99mTc-DMSA scan demonstrates reliable sensitivity and NPV for effectively excluding high-grade VUR. These findings suggest that in children with normal results from both US and ^99mTc-DMSA scans, there may be no need for VCUG. This approach could significantly reduce unnecessary VCUG procedures, minimizing patient exposure to radiation and enhancing overall diagnostic efficiency in pediatric care.

Keywords: Technetium-99m-Dimercaptosuccinic acid; Ultrasound Urinary tract infection; Vesicoureteral reflux.