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Serial 99mTc dimercaptosuccinic acid (DMSA) scans after urinary infections presenting before the age of 5 years
1Queen Mary's Hospital for Children, Carshalton Hospital, Sutton.
Insights
Sequential technetium dimercaptosuccinic acid (DMSA) scans reveal that initial kidney damage from urinary tract infections in young children often persists. Early DMSA scans are crucial for understanding factors influencing renal damage development.
Area of Science:
- Pediatric Nephrology
- Diagnostic Imaging
Background:
- Urinary tract infections (UTIs) are common in children under five.
- Renal scarring can result from UTIs, potentially leading to long-term complications.
- The role of sequential imaging in assessing UTI outcomes needs further clarification.
Purpose of the Study:
- To evaluate the persistence of renal cortical defects after a first urinary tract infection (UTI) in children under five.
- To identify factors influencing the development and progression of renal damage using sequential 99mTc dimercaptosuccinic acid (DMSA) scans.
- To understand the relationship between vesicoureteral reflux (VUR), recurrent infections, and renal scarring.
Main Methods:
- A cohort of 45 children under five with their first proven UTI underwent sequential 99mTc DMSA scans.
- Renal defects and relative DMSA uptake were assessed at presentation and during follow-up.
- Data on vesicoureteral reflux (VUR) grade and symptomatic recurrences were collected.
Main Results:
- Eighty percent of initial renal defects detected by DMSA scans persisted on follow-up.
- Defect changes were independent of initial VUR grade or infection recurrence.
- Deterioration was associated with new infection and grade 3 VUR; kidneys with <35% uptake did not improve.
- New defects developed only in one patient with bilateral grade 3 VUR and breakthrough infections.
Conclusions:
- The outcome of a UTI is significantly influenced by the initial renal damage sustained.
- Sequential DMSA scanning is valuable for assessing renal damage progression in pediatric UTIs.
- Widespread DMSA scan use can enhance understanding of factors leading to renal damage.
Abstract:
Forty five children presenting with a first proven urinary tract infection under the age of 5 years were studied by sequential 99mTc dimercaptosuccinic acid (DMSA) scans. Forty nine kidneys in 40 children had definite defects at presentation, and 39 (80%) of these defects were still present when the DMSA scan was repeated. Changes in the appearance of defects were independent of the presence or degree of reflux at presentation and of symptomatic recurrence of infection, though the combination of new infection and grade 3 reflux (reflux reaching the renal calices with distension) was associated with deterioration. No kidney with a relative DMSA uptake of less than 35% showed any improvement in its cortical defects. Only two kidneys that were initially without defects, in a single patient who had bilateral grade 3 reflux and breakthrough infections, developed defects on subsequent scans. The outcome after urinary tract infection is dependent on the effect of the first infection on the kidney. Occasionally children with grade 3 reflux develop damage during subsequent infections. More widespread use of DMSA scans should improve our understanding of the factors that determine the development of renal damage.