99mTc dimercaptosuccinic acid (DMSA) scan as first investigation of urinary tract infection

A total of 115 children under 5 years who presented with a first symptomatic urinary tract infection and who had a 99mTc dimercaptosuccinic acid (DMSA) scan were studied to assess its value and compare the findings with those of other imaging techniques. Renal cortical defects were detected in 65 kidneys by DMSA scan, intravenous urogram, and ultrasound scan combined; 62 (95%) being seen on DMSA scan. The finding of reflux on micturating cystourethrography showed a highly significant correlation with renal defects seen on DMSA scanning, a less close but still significant correlation with abnormalities on intravenous urography, but none with ultrasound scan findings. The sensitivity of the DMSA scan in screening for all grades of reflux is estimated as 0.66, which is higher than that previously reported for the intravenous urogram or ultrasound scan. DMSA scans were less likely to miss grade 3 reflux than the other two methods. DMSA scans are more useful than other upper renal tract imaging techniques in detecting renal defects. Consideration should be given to their use as a first investigation in place of routine intravenous urograms. Ultrasound scans alone will overlook potentially serious urinary tract abnormalities.