Tc-99m DMSA renal scan in first-time versus recurrent urinary tract infection-yield and patterns of abnormalities.

PURPOSE: To determine the yield and patterns of abnormalities noted by Tc-99m DMSA renal imaging in cases of first-time versus recurrent urinary tract infections (UTIs) in children.

MATERIALS AND METHODS: We reviewed 101 Tc-99m DMSA studies performed for 52 first-time and 49 recurrent UTIs in 99 children during a period of 1 year. The average age of the patients was 4.4 years, and the female:male ratio was 7:1. Static images of the kidneys were acquired 2 hours after injection of Tc-99m DMSA in anterior, posterior, and right and left posterior oblique views. SPECT was performed in 9% of the cases. The studies were scored as normal or abnormal.

RESULTS: The yield of abnormal scans in first-time UTIs was 22 (42%) and in recurrent UTI 27 (55%). Three categories of abnormalities were noted: 1) renal cortical defects (55% of the abnormal scans in first-time UTIs and 59% of the abnormal scans in recurrent UTIs; P = 0.40); 2) dilated pelvicalyceal system (27% of the abnormal studies in first-time UTIs and 63% of the abnormal studies in recurrent UTIs; P < 0.01); and 3) renal swelling showing disproportionate function with size (41% of the abnormal scans in first-time UTIs and 22% of the abnormal scans in recurrent UTIs; P = 0.21).

CONCLUSIONS: The high yield of renal abnormalities by Tc-99m DMSA scanning emphasizes the importance of testing all cases of UTI, including patients with a first-time infection. Documentation of the pattern of abnormalities may help in planning for subsequent management of UTIs in these patients.