Ultrasound looks for obstruction and structural anomalies; the micturating cystourethrogram grades vesicoureteric reflux (I–V); DMSA shows scarring — who needs which depends on age and the type of infection (NICE/AAP pathways).
Orient first
- Not every child with a UTI needs an MCUG; atypical or recurrent infection and abnormal ultrasound raise the need (verify the pathway your hospital follows).
- International reflux grading I–V by the calyceal and ureteric appearance on MCUG.
- DMSA at 4–6 months after infection shows permanent scarring; acutely it shows pyelonephritis.
Acquire the study
- Curvilinear probe; both kidneys and the bladder, full and post-void.
The manoeuvre
- Kidney length in cm against age centiles; corticomedullary differentiation.
- Pelvicalyceal dilatation: APRPD in mm (UTD classification).
- Ureteric dilatation behind the bladder; ureterocele.
- Bladder wall thickness; post-void residual volume in ml.
What confirms it
- Reflux demonstrated on MCUG with a grade; scarring on DMSA at the right interval.
What licenses you to exclude it
- A normal MCUG excludes reflux at the time of the study.
The classic misread
- A normal ultrasound does not exclude reflux.