Review Question - QID 104603

Following the acute phase of her illness, imaging with a renal bladder ultrasound (RBUS) is recommended in order to identify any urinary tract anatomic abnormalities that may predispose a child to recurrent urinary tract infections. A RBUS is also useful in predicting renal scarring.

A renal bladder ultrasound (RBUS) is recommended among children who fulfill any of the following criteria: younger than 2 years of age with a first febrile UTI, child of any age with recurrent UTIs, children with a UTI and a family history of renal disease, inadequate growth or hypertension, or a child who did not respond to empiric therapy for a UTI. A RBUS is able to identify any gross anatomic abnormalities, ureter duplication, or renal or perirenal abscesses. It cannot definitively diagnose vesicoureteral reflux, but is useful in predicting the risk of renal scarring.

In his review, White discusses the epidemiology of UTIs in children. Eight percent of female children and 2 percent of boys experience a UTI by 7 years. The most common causative organism is E. coli. With increasing rates of E. coli resistance to amoxicillin, empiric therapy with trimethoprim/sulfamethoxazole or third generation cephalosporins is appropriate.

Nagler et al. discuss interventions for vesicoureteral reflux in their review. Compared with no treatment, the use of prophylactic antibiotics decreased the risk of new or progressive renal damage but did not decrease the overall incidence of recurrent febrile of symptomatic UTIs. The benefit of surgical correction over antibiotic therapy is also unclear. While there was a decrease in the number of recurrent, febrile UTIs, there was no difference in renal damage.

Illustration A is an image from a renal bladder ultrasound demonstrating a dilated ureter as seen in vesicoureteral reflux (normal diameter of ureter is 2-4 mm with diameters larger than this are considered dilated). Illustration B in an image from a VCUG that demonstrates bilateral grade III reflux, with contrast infiltrating the renal parenchyma.

Incorrect Answers:
Answer 1: While currently available studies are in conflict with regard to efficacy, prophylactic antibioitic therapy should be considered in children who have documented VUR, a family history of VUR or a severe UTI. This child does not fulfill these criteria.
Answer 2: A VCUG is the test of choice to determine the presence of and extent of vesicourethral reflux. Given the radiation associated with this test, a RBUS is typically the first choice. Among children with their first febrile UTI, a VCUG is recommended if 1. Abnormalities are found on RBUS, 2. They have a fever >39°C with an organism other than E. coli, or 3. They have poor growth or hypertension.
Answer 4: Repeat urine culture is unnecessary in a child who has clinical improvement and is treated with an appropriate antibiotic.
Answer 5: Renal scintigraphy can be used to determine how extensively the kidneys are affected by a UTI. However, given this test's expense and greater exposure to radiation, RBUS and VCUG are preferred diagnostic methods.