antenatally diagnosed hydronephrosis

8/22/2019 Antenatally Diagnosed Hydronephrosis

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Antenatally diagnosed hydronephrosis:

current postnatal management

Michael T. Davenport Paul A. Merguerian

Martin Koyle

Pediatr Surg Int (2013) 29:207214


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INTRODUCTION


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Since the late 1970s, prenatal screening with

ultrasound has become a routine component

of care for pregnant women worldwide.

Studies have found that approximately 1 % of

ultrasounds detect fetal anomalies.

Of these detected anomalies, genitourinary

abnormalities are amongst the most common,

accounting for 20 % of identified anomalies


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Antenatal hydronephrosis (ANH), defined as

dilation of the fetal renal collecting system

affects between 1 and 5 % of pregnancies


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The differential diagnosis of antenatal

hydronephrosis is quite broad ranging from

ureteropelvic junction obstruction, vesicoureteral

reflux, and posterior urethral valves

Left untreated these pathologies may result in

postnatal morbidity including nephrolithiasis,

urinary tract infection, renal scarring andultimately, renal loss, and chronic kidney disease


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ANH represents a spectrum, with most cases

being a trivial and inconsequential finding on

maternal fetal ultrasound.

the vast majority of ANH is transient in nature

and resolves spontaneously without

intervention or complication, and hence is a

benign, yet worrisome peculiarity


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Current practice regarding the evaluation and

treatment of children with ANH remains in flux

within the pediatric urology community and is far

from uniform and often is based on dogma,training, and personal or institutional bias.

Although algorithms have been devised to

investigate the infant with ANH, none are perfectfor each and every patient that is referred for

evaluation


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This manuscript reviews the primary literatureand consensus statements pertaining to ANHand sets forth our own recommendations

regarding management of infants with thisfinding.

The vast majority of this work is based onupper tract pathology relating to ureteropelvicjunction obstruction as the subject is far tooimmense to similarly review all causes of ANH


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NATURAL HISTORY OF ANTENATALHYDRONEPHROSIS


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PRENATAL DETECTION OF ANH


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Prenatal ultrasound screening is mostcommonly performed at 1820 weeksgestation, which also coincides with the point

at which renal architecture becomes visiblydistinct.

The most commonly utilized parameter fordetermining the presence and severity of ANHon prenatal screening is the anteriorposteriordiameter (APD) of the renal pelvis.


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as of yet no predetermined APD value which

discriminates pathological from benign ANH

Establishing such a threshold is difficult

because of variation in APD associated with a

number of factors including gestational age

and maternal hydration status.


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Multiple studies have examined the APD

measured on prenatal ultrasound necessary to

predict postnatal pathology


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Ismaili et al. prospectively followed

213 infants

APD cut off of 10 mm in the third trimester

detected only 23 % of renal anomalies.

APD cut off of 7 mm in the same patient

cohort detected 68 % of abnormalities

suggesting that a lower APD cut off provides

greater sensitivity in detecting pathology


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Coplen et al retrospectively evaluated a

cohort of 257 neonates

APD cut off of 15 mm detected renal

pathology in approximately 80 % of fetuses

with a sensitivity of 73 % and a specificity of

82 %.


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CLASSIFICATION OF ANTENATALHYDRONEPHROSIS


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A number of grading systems have been

utilized to classify ANH, but they are all

complicated by subjectivity and inter-provider

variability

In order to overcome this subjectivity, more

objective parameters have been implemented,

namely APD


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Lee et al

meta-analysis of 17 studies and a total of

1,308 subjects with antenatal hydronephrosis

and were able to stratify ANH based on the

size of the APD on prenatal ultrasound.

Their analysis also found a difference in APD

threshold based on gestational age.


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Mild disease was categorized by an APD


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Animal models have shown that urinary obstructionnot only results in renal dysplasia and kidney failure,but due to decreased amniotic fluid, normal pulmonarydevelopment is impeded

Currently, intervention, such as open fetal surgery,vesicocentesis or renal pelvis aspiration, is reserved for

fetuses with solitary kidney and severe hydronephrosisand oligohydramnios or in fetuses with posteriorurethral valves and oligohydramnios. Intervention is

only recommended in the second and third trimestersand carries significant morbidity and mortality limitingits utility


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While APD measurement provides an

objective means of predicting pathology, most

in the field would agree that other features

are also important in determining severity ofthis finding. Therefore,

features such as calyceal dilation and

parenchymal thinning should be considered ingrading the severity of ANH.

th S i t f F t l U l (SFU)


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the Society for Fetal Urology (SFU)

took these

factors into account The system grades hydronephrosis on a five-point scale with

grade 0 representing normal renal ultrasound

grade 1 demonstrates the onset of

hydronephrosis

grade 4 hydronephrosis with dilation of the

pelvis and major calyces in addition to

thinning of the parenchyma


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LONG-TERM OUTCOMES


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Perhaps the best data about long-term

outcomes in patients with antenatal

hydronephrosis come from the anecdotal

accounts of Dhillon [11] and the experience atthe Great Ormond Street Hospital in London

and as further described by Thomas


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cohort of 76 children

all having function < 40 %

observed for a minimum of 16 years.


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52% significant or complete resolution of

hydronephrosis without recurrence

11 % stable hydronephrosis without

complication or intervention.

37 % eventually underwent pyeloplasty for

increased dilation, decreased differential

function or onset of symptoms such as

infection


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Ulman et al

104 neonates with severe unilateral ANH

23 children eventually required surgery.

Of the remaining , 69 % resolved within 2.5

yrs

31% had persistent but improvedhydronephrosis

Children with differential function of


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Ismaili et al.

Retrospective data for a cohort of 234 neonates

Over longer period of time, up to 13 years.

22 % required early pyeloplasty for reduced

function. Remaining 182 children managed conservatively

with observation and 137 found to have stable orimproved renal function.

Delayed pyeloplasty was performed in 45 of the182 neonates for decline in differential functionor UTI at a mean age of 18 months


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OBSERVATION VERSUS EARLYINTERVENTION


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Majority children with antenatally diagnosed

hydronephrosis will have spontaneously

resolving dilation or remain asymptomatic

with persistent dilation

~ 2533 % of cases will worsen over the

course of observation with decreased renal

function or infection and require surgicalintervention


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Organizations such as the Society for Fetal

Urology (SFU) and Canadian Urological

Association (CUA) have put forth

recommendations to guide practitioners,

But the community remains divided on their

interpretation of the available data


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ANTIBIOTIC PROPHYLAXIS


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As of date, there have not been any

prospective randomized trials evaluating the

utility of prophylactic antibiotics in children

with ANH.

There are multiple conflicting retrospective

studies, some showing an increased risk of UTI

and others not, and the topic remainscontroversial


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Retrospective cohort analysis

Walsh et al:Infants with hydronephrosis 12times more likely to be hospitalized forpyelonephritis in the first year of life

Coelho et al.: incidence of infection with mild,moderate, and severe hydronephrosis was 11,18, and 36 %, respectively, at 36 month

Lee et al.: rate of infection ~40 % in neonateswith SFU grade 4 hydronephrosis, even whencontrolling for reflux


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An equal number of studies that demonstrate

a low risk of urinary tract infections in children

with ANH without vesicoureteral reflux.

Estrada et al. :1,514 /2,076 with ANH grade 2

hydronephrosis screened for VUR

Of the 828 patients who did not have reflux,

only 11, or 1.3 % ultimately developed UTI


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Roth et al.: h/o UTI in only 4.3 % of 92 children

with grade 3 or 4 hydronephrosis without

reflux

a slightly higher rate ofUTI, 8.3 %, in children

with hydroureter


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Canadian Urological Association (CUA) recognizedthe ambiguity surrounding the issue and onlyconferred a grade D recommendation for caseswithout reflux

SFU recommended the use of prophylacticantibiotics in all cases of hydronephrosis exceptfor the most mild.

recommends antibiotic use for children withadditional risk factors for UTI such as hydroureterand reflux


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CIRCUMCISION


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Even more ambiguous and controversial thanthe the use of prophylactic antibiotics

Most recently, the American Academy of

Pediatrics increased their support of theprocedure given the evidence of preventingurinary tract infection, HIV transmission, andpenile cancer

but does not recommend routine circumcisionfor all newborns


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Several studies have shown that circumcisioncan prevent UTI with VUR and PUV.

Mukherjee et al.:retrospective analysis of 78

uncircumcised pts with PUV 27 circumcised : 83 % reduction in the

incidence of UTI

Herndon et al. found similar results in theirmulticenter study of children withvesicoureteral reflux


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HDN without hydroureter/ PUV : less prolific.

Roth et al: none of the circumcised children

grades 3 and 4 hydronephrosis developed UTI


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all retrospective studies

to date, no prospective randomized trials to

verify the utility of circumcision.

Unlikely in the future given the delicate and

personal nature of the procedure

decision to pursue circumcision must be

individualized to each child and family


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RENAL ULTRASOUND


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Important means of evaluating infants with

ANH both in both initial and follow-up phases

Allows for the differentiation of low- and high-

risk disease based on SFU grading criteria of

02 and 34, respectively


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Advantages

absence of radiation

ease of use

non-invasive

readily accessible in most locations

The available data: monitoring SFU criteria

and measuring APD can help predict whichpatients will require surgical intervention and

guide further treatment


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Disadvantages

a high degree of interoperator variability inskill and interpretation which can decreasepredictive value

Hydration status of the infant can also affectthe ability of ultrasound to predict pathology.

At birth, infants are relatively dehydrated andtherefore an ultrasound performedimmediately after birth can underestimate thedegree of hydronephrosis


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Vast majority of ANH is detected during the

second trimester around 20 weeks gestation

Abnormal findings then generally followed

with repeat prenatal ultrasound during the

third trimester and almost always with renal

ultrasound during the postnatal period

SFU: recommendation in all cases of ANH

CUA: grade A recommendation


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SFU & CUA recommend postponing the initialpostnatal renal ultrasound until at least 1 weekafter birth

unless necessitated by symptoms such as febrileinfection or rising creatinine

Children with additional risk factors for renaldamage including those with severe bilateral

hydronephrosis and any grade of hydronephrosisin a solitary kidney: ultrasound be performedprior to discharge from the hospital at birth.


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The CUA recommends using ultrasound inconjunction with SFU grading criteria toclassify patients into observational groups and

cases requiring additional evaluation. SFU grades 02 can be observed closely with

annual imaging to detect worsening ofhydronephrosis, but more severe disease,

grades 34, often necessitate a moreextensive workup

Dhill d i h G


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Dhillon and associates at the Great

Ormond Street Hospital

Measuring APD can help predict the need forsurgical intervention

Differential function > 40 % over a period of 613

years with conservative management. For kidneys with an APD between 30 and 40 mm,

21 out of 25 eventually required surgery tocorrect obstruction.

Additionally, they followed 36 kidneys with anAPD < 40 mm and found that all of themeventually required surgical correction


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VOIDING CYSTOURETHROGRAM


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Standard component in the evaluation of

infants with ANH to detect vesicoureteral

reflux and lower tract pathology such as

posterior urethral valves, ureteroceles orbladder diverticula


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SFU & CUA have recommended that all casesof ANH found on renal ultrasound to have SFUgrade 4 dilation undergo VCUG to rule out

reflux and other potential pathology Also recommend that VCUG be deferred for

less severe cases of ANH, SFU grades 02, asthe modality is more invasive than ultrasound

and these children have not been shown toprogress to significant pathology


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The recommendations become equivocal,however, when dealing with ANH classified asSFU grade 3 as this group of kidneys has the mostconflicting data regarding progression ofpathology

recommended that a more

individualized approach be taken with these

patients and the decision to pursue VCUG be made on a case

by case basis


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Factors which would influence the decision to

recommend VCUG include any findings which

suggest lower urinary tract disease like

posterior urethral valves.

These findings include bilateral

hydronephrosis, dilated ureter, duplex kidney,

abnormal renal echogenicity, and abnormalappearance of the bladder


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SUMMARY ANDRECOMMENDATIONS


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Antenatal hydronephrosis is the most commonlydiagnosed

anomaly on prenatal ultrasound. Meta-analysis hasshown

that these children have an increased risk of pathology

postnatally when compared with children within thenormal

population. However, the degree of this risk, like the

severity of hydronephrosis, varies largely betweenchildren.


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RECOMMENDATIONS


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SFU grades 02

Long-term data indicate that infants with low-

grade antenatal hydronephrosis have

resolution of dilation or remain stable without

pathological complication in the majority ofcases

Consequently, initial surgical intervention is

not indicated or recommended by either theSFUorCUA


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a protocol of expectant management

As per the recommendations of both the SFU

and CUA, all infants with antenatally

diagnosed hydronephrosis should have a renalultrasound shortly after birth, but no sooner

than 2 weeks of life to avoid the initial

postnatal diuretic phase


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SFU grade 3

antibiotic prophylaxis until the studies are

completed, particularly if the family chooses

to pursue a VCUG.

Ultrasound should be performed at 714 daysafter birth in an otherwise healthy infant


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counsel the family on performing a VCUG toevaluate for reflux.

If VCUG is negative for reflux we would

recommend discontinuing antibiotic prophylaxis.If no VCUG is performed, again a frank discussionwith the family is in order, and a decision madeafter providing the data available and respecting

their sense of comfort. Circumcision also becomes a decision based on

similar models


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We would recommend repeating the

ultrasound at around 3 months of age and if

the degree of hydronephrosis remains the

same or worsens a Tc-MAG 3 diuretic renalscan should be performed.


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SFU grade 4

should be placed on prophylactic antibiotics

until the studies are completed. Particularly, if

there is ureteral dilation, a VCUG should be

encouraged. If the VCUG shows no reflux antibiotics may

be discontinued, even realizing that the

retrospective data suggests an increased riskof UTI in this group of children


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Children with grade 4 hydronephrosis have

the most severe renal anomalies and, as

shown in the above longterm follow-up data,

the greatest risk for developing renalpathology.

most often require surgical intervention to

prevent said adverse events.


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that renal ultrasound should be performed after 2weeks of

life to reassess renal dilation. Furthermore, because ofthe

increased risk of pathological outcomes in thesechildren,

VCUG should be encouraged. If vesicoureteral reflux is

found a DMSA scan may be offered in selected cases in

order to evaluate differential function.


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If the VCUG is

negative for reflux a diuretic renogram should beperformed

to elucidate etiology of hydronephrosis and plan for

potential surgical management. Again, because of the

conflicting data regarding antibiotic prophylaxis andcircumcision

in children with ANH, we recommend that they be reserved for symptomatic cases


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Hydroureter

risk of developing urinary tract infection isgreater than in children with dilation limited tothe kidney

It is our recommendation, and that of the SFU,that these children undergo imaging within thefirst 7 days, including at least a renal ultrasound.

Similarly, these patients should also be placed on

antibiotic prophylaxis until imaging studies arecomplete because of their increased risk ofinfection.


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Bilateral hydronephrosis

there is new evidence, which, while limited,suggests that children bilateral hydronephrosismay benefit from early evaluation and

antibiotic prophylaxis. at increased risk of infection

Increases with the grade of hydronephrosiswith bilateral severe hydronephrosis havinghigher incidence of infection than mildercases.


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we recommend, along with the SFU and CUA, thatthese children be placed on antibiotic prophylaxiswhile awaiting studies to be completed.

Bilateral hydronephrosis not only carries an increased

risk of infection, it may also be a sign of more severeunderlying pathology such as posterior urethral valvesin boys.

Therefore, it is recommended that these children be

evaluated with ultrasound and potentially VCUG priorto being discharged from the hospital after birth

antenatally diagnosed hydronephrosis

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