Page 1 - Canadian Urological Association/Pediatric Urologists of Canada guideline on the investigation and management of antenatally detected hydronephrosis

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CUA GUIDELINE

Canadian Urological Association/Pediatric Urologists of Canada

guideline on the investigation and management of antenatally

detected hydronephrosis

John-Paul Capolicchio, MD ; Luis H. Braga, MD ; Konrad M. Szymanski, MD, MPH 3
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1 Montreal Children’s Hospital, McGill University Health Centre, Montreal, QC, Canada; McMaster Children’s Hospital, McMaster University, Hamilton, ON, Canada; Riley Hospital for Children at Indiana
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University Health, Indianapolis, IN, United States
Cite as: Can Urol Assoc J 2018;12(4):85-92. http://dx.doi.org/10.5489/cuaj.5094 Characterizing the patient population

Published online December 22, 2017 The literature on AHN suffers from a lack of good-quality
prospective studies, which precludes any recommendations
with a high level of evidence. Published prospective stud-
See related commentary on page 93 ies are hindered by the limitation that to this date no single
gold standard diagnostic test for urinary obstruction exists. In
order to appreciate this dilemma, it is imperative to under-
Introduction stand the difference between hydronephrosis and urinary
tract obstruction. Hydronephrosis simply refers to dilation
Prior to the advent of maternal ultrasonography in the of the renal collecting system. Congenital renal obstruction
1980s, children with significant congenital hydronephrosis has been defined as, “impaired urinary drainage, which, if
requiring surgery presented symptomatically with abdom- uncorrected, will limit the ultimate functional potential of
inal pain, urinary infection, hypertension, hematuria, or the developing kidney.” To date, no single imaging study
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failure to thrive. Antenatal hydronephrosis (AHN) became exists that can prove the presence of renal obstruction, con-
one of the most commonly detected ultrasound (US) find- tributing to the controversy surrounding management.
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ings, affecting 1‒5% of pregnancies. The majority of AHN The differential diagnosis of AHN, in order of likelihood,
in the third trimester is discovered due to US for maternal includes transient primary hydronephrosis, uretero-pelvic
indications. The benefits of this early detection of urinary junction obstruction (UPJO), vesicoureteric reflux (VUR),
tract dilation include a reduction in the renal damage due uretero-vesical junction obstruction (UVJO) or primary
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to obstruction and infection. On the other hand, many of non-obstructive megaureter, ureterocele, ectopic ureter,
these antenatally detected cases spontaneously resolve with and causes of megacystis. Megacystis, or dilated urinary
observation and consequently can be submitted to unneces- bladder, includes causes of bladder outlet obstruction due
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sary investigations and continued medical followup. The to posterior urethral valves (PUV) and, less commonly,
challenge to this day remains to predict which of these pre- Prune Belly syndrome, megacystis-megaureter syndrome,
natally detected infants will require corrective surgery, prior megacystis-microcolon intestinal hypoperistalsis syndrome
to the development of symptoms or potentially irreversible (MMIHS), anterior urethral valves, megalourethra, urethral
renal damage, thus permitting a more tailored screening. atresia, and cloacal anomalies. Some of these entities have
gender-specific and hereditary predispositions, which have
Methodology potential diagnostic implications not discussed herein.
Various grading systems for the severity of AHN exist,
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This article presents an update to the 2009 guidelines, based which are paramount in decision-making. The simplest
on review of the current literature. The available evidence is grading is the antero-posterior renal pelvic diameter (APD),
summarized and recommendations provided based on the which is an objective measure of the degree of pyelecta-
modified Oxford Centre for Evidence‐Based Medicine grad- sis or dilation of the renal pelvis in the transverse plane.
ing system for guideline recommendations, as employed by Descriptors such as mild, moderate, or severe should not
the International Consultation on Urologic Disease. 6 be used in isolation, as they are subjective and undefined.
Since 1993, the standard among pediatric urologists in North

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