Antenatally Diagnosed Hydronephrosis
Transcript of 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