Congenital malformations - Edocr

256 PART VII RENAL MALFORMATIONS
anal, cardiac, tracheal, esophageal, renal, and
limb) association in 19%, unrecognized multiple
malformation syndrome in 17%, and chromosomal
disorder were identified in 6% of the cases. 10
Chromosomal abnormalities were also reported
in 7% of cases with bilateral renal agenesis from
a large population based study from Europe. 9
Table 39-2 provides a brief list of syndromes
frequently associated with renal agenesis.
EVALUATION AND MANAGEMENT
A detailed history of index pregnancy, family
history and complete physical examination to
evaluate for any associated congenital anomalies
of other organ systems are necessary and
helpful in the evaluation of an infant with renal
agenesis. A history of oligohydramnios and anuria
with presence of IUGR, Potter facies, and severe
respiratory failure strongly indicate the possibility
of bilateral renal agenesis and an emergent renal
ultrasound should be obtained in these infants.
In contrast, as noted earlier, an infant with
unilateral renal agenesis with normal contralateral
kidney is likely to have normal amniotic
fluid volume, normal urine output and renal
function studies, and be completely asymptomatic.
Renal ultrasound is the quickest and the
best test to evaluate kidneys in a newborn infant.
However, it is important to remember that
the absence of kidney/kidneys in its normal position
does not always mean renal agenesis as
they could be ectopic or dysplastic and small. A
renal scan or magnetic resonance imaging (MRI)
should be considered if ultrasound is inconclusive.
A fetal MRI to evaluate renal anomalies is
particularly promising because oligohydramnios
can impair visualization of the fetal kidneys
on ultrasound examination. Color Doppler
sonography has also been shown to be helpful
in these situations. A skeletal survey and
echocardiogram should be done in all infants
with renal agenesis because of high likelihood
of VACTERL association and congenital heart malformations
in these infants. A plain film of abdomen
after placing a nasogastric tube and careful
perineal examination for imperforate anus are helpful
in excluding common GI anomalies. A cranial
ultrasound and karytope should be considered in
the presence of extrarenal anomalies but the likelihood
of an abnormal result is low in infants
with unilateral renal agenesis with no extrarenal
anomalies. It has been recommended that renal
ultrasound should be performed on parents and
siblings of an infant with renal agenesis. Roodhoft
et al reported a 9% incidence of asymptomatic
renal malformations including unilateral
renal agenesis in 4.5% of parents and siblings. 15
The evaluation of contralateral kidney and lower
genitourinary tract on both sides should be done
in all infants with unilateral renal agenesis. Routine
urine analysis, serum chemistries with blood
urea nitrogen, and serum creatinine are necessary
to assess the degree of renal impairment
and follow-up of renal function. All infants
should receive prophylactic antibiotics pending a
complete evaluation. Renal scan and voiding cystourethrogram
(VCUG), with or without cystoscopy
are helpful in evaluation of contralateral kidney
and lower urinary tract. Pelvic ultrasound or computed
tomography (CT) and colposcopy may be
helpful in female patients for early identification of
associated anomalies of uterus and vagina. The
recommended evaluation for all infants with renal
agenesis is summarized in Table 39-3.
PROGNOSIS
Bilateral renal agenesis is incompatible with life.
Majority of infants die secondary to respiratory
failure unresponsive to maximal medical management.
Use of extracorporeal membrane oxygenation
(ECMO) is usually contraindicated in
these infants and withdrawal of support is considered
acceptable after parental consent. There
are no reports of long-term survival among infants
with bilateral renal agenesis.
Infants with unilateral renal agenesis with normal
contralateral kidney have a good prognosis
with high likelihood of normal life span in the
majority of cases. The contralateral kidney in
these infants undergoes a prenatal and postnatal