Ultrasound in Urinary Tract Infection and Vesico-Ureteric Reflux in Children

Urinary tract infections (UTI) in children are common and are associated with significant morbidity and the need for hospitalisation. The development of a UTI depends upon host factors such as immunity and the presence of urinary tract abnormalities as well as virulence of uropathogens. Microorganisms from the periurethral area can ascend to the urinary bladder causing cystitis; this infection can further climb to involve the upper urinary tract, leading to pyelonephritis and bacteremia. Kidney scars may develop in pyelonephritis and can be responsible in the long term for hypertension and kidney dysfunction which can progress later into end-stage kidney disease as well, especially if recurrent. Radiological assessment in a child with UTI is useful in determining the level of infection, possible complications which may have a bearing on the treatment approach, as well as identifying any structural abnormality which may be the underlying causative factor in a UTI. An ultrasound is an essential investigation in all UTIs in children. It is less accurate in picking up VUR and pyelonephritis than other investigations such as DMSA scan or micturating cystourethrogram (MCUG); however, it remains the most relevant first investigation in all age groups. Dilatation of the collecting system could also result from reflux, which could be primary or secondary to conditions such as neurogenic bladder or posterior urethral valves (PUV). It is also essential to assess the bladder and also postvoid residue in children with recurrent UTI. This chapter shall deal with the essentials of paediatric radiology in childhood urinary tract infections and vesicoureteric reflux.