Fig. 8.39 A micturating cystourethrogram showing grade V VUR. Note also the enlarged urinary bladder

8.6Investigations

•VUR not only increases the frequency of UTI’s, but also the risk of damage to upper urinary structures.

•Vesicoureteral reflux can result in substantial morbidity, both from acute infection and from the sequelae of reflux nephropathy.

•Early diagnosis and treatment of VUR is crucial to avoid permanent renal cortical scarring and subsequent renal insufficiency.

•CBC

•ESR and C-reactive protein

•BUN, serum electrolytes and creatinine

•The diagnosis of UTI depends on urine analysis and urine culture.

•The 2011 American Academy of Pediatrics (AAP) guidelines specify that both a urinalysis showing pyuria and a culture growing more than 50,000 CFU/mL should be the basis for a diagnosis of UTI.

•To diagnose UTI, it is important to obtain a non-contaminated urine specimen.

–A clean-catch midstream urine specimen is the most acceptable method especially in children who are toilet trained.

–Growth of more than 100,000 CFU/mL is a significant finding on a midstream-voided specimen.

–Suprapubic urine aspiration is used in infants and children.

–Any growth in suprapubic urine sample should be considered significant.

–Urethral catheterization is an alternative way to obtain a clean urine sample but it is more invasive.

–Growth of more than 1,000 colony-form- ing units (CFU)/mL is considered significant in a urine sample obtained by urethral catheterization.

–The least reliable method is the most common method of obtaining a urine specimen in babies. A urine sample is obtained from a urine collection bag. This method is not reliable and should be discouraged.

–This method is more useful if there is no growth in the urine sample as false-negative results are unlikely.

–As many as 10 % of urine specimens obtained by this method grow more than 50,000 CFU/mL with no correlation to actual presence of infection.

•Imaging studies are the basis of diagnosis and management of VUR.

•The standard imaging tests include renal and bladder ultrasonography and voiding cystourethrography (VCUG) (Figs. 8.40 and 8.41).

•Indications for imaging studies are as follows:

–After the first UTI in all children younger than 5 years

–Children of any age with febrile UTI

–Boys of any age with UTI

–Children with prenatally diagnosed hydronephrosis should be evaluated postnatally.

–Ultrasonography should be performed after the first 3 days of life.

–Ultrasonography performed during the first 3 days of life may have a high rate of falsenegative results because of relative dehydration during the neonatal period.

•The following radiological investigations can be performed to evaluate for VUR:

•Ultrasonography

•VCUG or radionuclide cystography (RNC)

•Grade II: Reflux into renal pelvis and calyces without dilation

•Grade III: Reflux with mild to moderate dilation and minimal blunting of fornices

•Grade IV: Reflux with moderate ureteral tortuosity and dilation of pelvis and calyces

•Grade V: Reflux with gross dilation of ureter, pelvis, and calyces, loss of papillary impressions, and ureteral tortuosity

–VCUG should not be performed in the presence of UTI and should be delayed till the child has fully recovered from the UTI. This should be confirmed with a fresh urine analysis and culture.

–Performance of VCUG during an episode of acute cystitis can result in overestimation of the grade of reflux because of paralysis and laxity of the ureteral musculature by bacterial endotoxin. Conversely, some children demonstrate reflux only during an episode of cystitis.

–VCUG outlines the urethra in males with posterior urethral valves.

–VCUG provides information in both boys and girls about bladder capacity and emptying and may reveal signs of outlet obstruction, such as bladder trabeculae or diverticula.

–Standard VCUG is recommended as the initial study in boys.

•Radionuclide cystography:

–This is performed by instillation of technetium-99m pertechnetate into the bladder and observation with a gamma camera.

–This is a highly sensitive test to diagnose VUR.

–The disadvantage of this investigation is the poor anatomical detail and failure to precisely classify the degree of VUR.

–Grade I reflux is poorly detected by this study, because the distal ureters are commonly obscured by the bladder

–Grading of VUR by nuclear cystography is limited to mild, moderate, and severe grades.

–Many clinicians use VCUG for the initial diagnosis and use RNC for follow-up studies.

•Dimercaptosuccinic acid (DMSA) renal scan:

–Although the traditional approach in children with UTI has been evaluation for vesicoureteral reflux with VCUG or radionuclide cystography (RNC), some authorities are now advocating a “topdown” approach for children with UTI.

–In this approach, a child with a history of febrile UTI undergoes a dimercaptosuccinic acid (DMSA) renal scan to assess for evidence of kidney involvement, kidney scarring, or both.

–Negative DMSA scan findings suggest that clinically significant vesicoureteral reflux is unlikely, obviating the need for VCUG.

–However, if DMSA scan findings are positive, VCUG is recommended.

–Reflux grade was significantly associated with the prevalence of renal scarring.

–VCUG is recommended after the first acute episode of infection is confirmed using dimercapto-succinic acid scintigraphy.

–Areas of acute inflammation or scarring do not take up the radiopharmaceutical and are revealed as cold spots on imaging.

–DMSA is used to identify and monitor progression of renal scarring.

–Patients who are medically treated and develop new or progressive scarring are often considered candidates for surgical correction of vesicoureteral reflux.

–DMSA can also be used as a diagnostic tool during suspected episodes of acute pyelonephritis but this role is not well defined.

•Urodynamic studies (Cystometrography):

–These reveal functional abnormalities of the lower urinary tract.

–These studies are however difficult to perform in infants and small children.

–Urodynamic studies are important in patients with secondary VUR, such as patients with spina bifida, detrusor instability or boys whose VCUG is suggestive of residual posterior urethral valves.

–Antireflux surgery is much less successful in patients with secondary reflux, and because of this it is important to identifying