ultrasound diagnosis of fatal anomalies

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GROWTH DISTURBANCE
Growth Restriction
Definition: Varying limits have been defined:
birth weight lower than the 10th, 5th, or 3rd centile.
It is important to differentiate between infants
who are small as a result of placental insufficiency
and those who are small due to
genetic disposition.
Incidence: Depending on the definition (see
above), 3–10% of pregnancies, if correct birth
weight percentiles are applied.
Clinical history: The birth weight depends on
genetic factors. There are families in which small
infants are more frequent and these cases are not
the result of inadequate placental function.
Genuine placental insufficiency causing growth
restriction occurs, usually repeatedly, in
mothers who have certain underlying diseases—
for example, kidney disease, hypertension, or
thrombophilic disorders. Other important factors
for placental insufficiency include smoking
and alcohol consumption during pregnancy.
Embryology: Growth restriction may be the result
of uteroplacental insufficiency, environmental
factors, drugs, maternal infections,
or genetic disposition to small stature. Asymmetrical
growth restriction is characteristic for
placenta insufficiency: the head circumference
and femur length are larger than the abdominal
circumference, which is considerably smaller for
the gestational age.
Associated syndromes: Cornelia de Lange syndrome,
Russell–Silver syndrome (asymmetrical
growth restriction with normal head circumference
and dwarfism), Seckel syndrome, Smith–
Lemli–Opitz syndrome, Miller-Dieker syndrome,
Neu–Laxova syndrome, Freeman–Sheldon
syndrome, osteopetrosis (autosomal-recessive
disease with diffuse sclerosis of the skeletal
system, increased bone density, bone fractures,
widening of cranial ventricles and shortening of
the long bones), Wolf–Hirschhorn syndrome, Jacobsen
syndrome (11q deletion), triploidy,
trisomy 9, trisomy 10, trisomy 18, Harlequin syndrome
(autosomal-recessive disease with callus
formation and characteristic facial features:
“clown-like face”).
Ultrasound findings: Fetal measurements lie
belowthe expected values for the gestational
age. For accurate diagnosis of fetal growth restriction,
early measurements of crown–rump
length at 8–12 weeks of gestation are indispensable.
There are two types of growth restriction: 1,
symmetrical: in this type, the measurements of
head and abdominal circumference and femur
length are all belowthe expected values; and 2,
asymmetrical: the head circumference is normal,
but the abdominal circumference and length of
the extremities are too small. Oligohydramnios
is a common feature when there is placental insufficiency.
Using color-coded Doppler imaging,
pathological values are obtained in fetal vessels
and also in maternal vessels (increased vascular
resistance).
Clinical management: In severe forms of growth
restriction (belowthe 5th centile), especially if
the growth restriction is symmetrical and diagnosed
early in pregnancy and the Doppler values
are normal, karyotyping and exclusion of maternal
infections (TORCH) are necessary. Serial ultrasound
assessment, including Doppler
measurements, are indicated. If the maternal hematocrit
is high, hemodilution can be carried
out. Some centers have tried to nurture the fetus
artificially by infusions of amino acids or glucose
into the amniotic fluid or umbilical vein, but
without much success. Premature delivery is
often opted for, in severe cases by cesarean section.
A very high perinatal mortality rate of 75%
is caused by intrauterine fetal death and results
from severe placental insufficiency. Very early
premature delivery—as early as 24 or 25 weeks
of gestation—may be necessary to prevent intrauterine
mortality. When placental insufficiency
occurs repeatedly and very early, or if
there is a clinical history of fetal demise in a previous
pregnancy, anticardiolipin antibody, lupus
anticoagulant, or thrombophilic disorders may
be the causative factors. In such cases, early therapy
with low-dose acetylsalicylic acid and
possibly heparin may be needed.
Procedure after birth: A pediatrician should be
present at birth. There is a high incidence of fetal
distress during labor and delivery.
Prognosis: There is a fourfold to eightfold increase
in perinatal mortality in severe cases of
growth restriction (below the third centile). The
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