To V(CUG) or Not to V(CUG) in Infants with Prenatal Hydronephrosis?

THIS is a critical question that may throw even the The idea of being able to more accurately use ul-

noblest of pediatric urologists into a quandary. Ourdesire to help our patients simply will not allow usto stand idle and watch them “suffer the slings andarrows of outrageous fortune” that vesicoureteralreflux (VUR) can yield.1 “To take arms against asea of troubles” is our alternative.1 The core of thismodern-day conflict is whether diagnosing VURin asymptomatic patients has long-term healthbenefits. Currently it is not clear which patientsdiagnosed prenatally will go on to have clinicallysignificant VUR.2,3 However, we do know that notall patients with VUR are created equal. In fact,some patients have no sequelae from VUR whileothers have recurrent urinary tract infections(UTIs) and a minority of these patients has renalscarring.

Before the widespread use of prenatal ultraso-nography, VUR was discovered in patients whenthey manifested clinically with febrile UTI. Radio-logic investigation with voiding cystourethrography(VCUG) was required to determine the etiology ofthe problem and guide therapy. Prenatal ultraso-nography reversed this paradigm through theidentification of urinary tract abnormalities in thefetus, specifically with the detection of prenatalhydronephrosis.

Studies have linked prenatal hydronephrosis topostnatal pathology. With increasing grades ofprenatal hydronephrosis, the likelihood of postnatalurinary tract pathology increases, but neither thepresence nor degree of hydronephrosis on prenatalstudies necessarily equates to the presence of VUR.4

Moreover a normal prenatal study defined by a lackof hydronephrosis does not exclude VUR.5 Never-theless, prenatal hydronephrosis often triggerspostnatal evaluation for VUR with VCUG. This hascontributed to the 2 separate issues of over-testingand over diagnosis. Because prenatal hydro-nephrosis is not a good predictor of VUR, a largeproportion of voiding cystourethrograms performedare negative.6,7 This is not inconsequential. VCUGcan cause stress for the patient and parent, mayincite UTI and exposes the child to radiation.8e10

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trasound findings to predict which patients needVCUG is a practical solution to over-testing. In thisissue of The Journal Lee et al (page 914) soughtto determine if any 1 of 3 additional renal andbladder ultrasonography criteria including hydro-ureter, renal dysmorphia and/or duplication couldimprove the ability to predict VUR in patients withprenatal hydronephrosis compared with the detec-tion rate when the trigger for VCUG is exclusivelyprenatal hydronephrosis.10 Applying the authors’criteria for radiographic investigation only 97 void-ing cystourethrograms were performed comparedwith 262 when prenatal hydronephrosis alonetriggered the test. With any 1 of the 3 aforemen-tioned findings positive on ultrasound, the positiveand negative likelihood ratios were 2.71 and 0.33,respectively. Assuming a VUR prevalence of 10% to15% among patients with prenatal hydronephrosis,the post-test probability that a patient had VURafter a positive test (ultrasound meeting at least 1of the 3 criteria) was 23% to 32%, and after a nega-tive test was 6.7%.

Using their proposed criteria 11 patients whohad VUR would have been missed (5 with highgrade VUR and 6 with low grade VUR). However, inthis subset 8 of 11 patients had VUR resolution ata mean followup of 17.3 months and only 1 of 11had a UTI that actually occurred after VUR reso-lution. Since some physicians more selectivelyobtain VCUG only when high grade prenatalhydronephrosis is present, the authors applied thiscriterion to their prenatal hydronephrosis popula-tion. Using this parameter they would have per-formed 163 voiding cystourethrograms and wouldhave missed a similar number of patients with VUR(10 vs 11).

The ability to more accurately predict whichpatients with prenatal hydronephrosis will haveVUR on VCUG based on ultrasound findings is animportant step in decreasing over-testing. However,we are still left with the more problematic issue ofover diagnosis. For many patients with prenatallydetected VUR the condition is a benign entity that

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often resolves spontaneously.5 The diagnosis ofVUR in this subset of patients carries little to noclinical benefit and arguably may be detrimental.

By limiting diagnosis to those with clinically sig-nificant VUR, we could prevent not only the poten-tial iatrogenic consequences of VCUG in clinicallyinsignificant cases, but also the downstream effectsof diagnosis such as antibiotic exposure, repeat im-aging, clinic visits, and patient and parental anxiety.Central to the solution is the ability to consistentlyidentify those patients who will have sequelae fromVUR. Although specific ultrasound findings may

enhance our ability to predict which patients shouldbe evaluated with VCUG, unnecessary testing forand diagnosis of VUR will continue until we estab-lish better markers to identify which children are athighest risk for clinically significant VUR.

To V(CUG) or not to V(CUG) is not precisely thequestion we should be asking. Rather, for whom dowe obtain VCUG? “That is the question.”1

Sisir Botta and Hillary L. CoppDepartment of Urology

University of California, San Francisco

San Francisco, California

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