Diagnostic ultrasound ( PDFDrive )

CHAPTER 40 The Fetal Musculoskeletal System 1401
FIG. 40.27 Radial Ray Anomaly Diagnosed at 13 Weeks’ Gestation.
Three-dimensional ultrasound surface display demonstrates the
hypoplastic radius and ulna in association with talipomanus (clubhand)
(arrow).
Diamond-Blackfan (Aase syndrome) is genetically a heterogeneous
condition with an autosomal dominant mode of
inheritance. It is associated with hypoplastic anemia, a hypoplastic
distal radius with radial clubhand, and a triphalangeal thumb.
Associated cardiac defects (ventricular septal defect, coarctation
of aorta) may be present. Triphalangeal thumb may also be found
in Holt-Oram syndrome, chromosomal abnormalities, and fetal
hydantoin exposure.
hrombocytopenia–absent radius syndrome is an autosomal
recessive blood dyscrasia characterized by hypomegakaryocytic
thrombocytopenia and bilateral absence of the radii. 93 he thumb
is present. he humerus and lower extremities are variably
involved. One-third of such patients have CHD, typically tetralogy
of Fallot or septal defects. Fetuses are at risk of intracranial
hemorrhage, so delivery by cesarean section is recommended
(Fig. 40.29). he causative gene is TBX5.
Holt-Oram syndrome is an autosomal dominant disorder
consisting of a congenital heart defect (atrial or ventricular septal
defect) in combination with a variety of upper limb anomalies.
he limbs are asymmetrically afected, with the let limb usually
showing more efects than the right. he lower extremities are
not involved. he causative gene is TBX5.
Roberts syndrome, or pseudothalidomide syndrome, is an
autosomal recessive disorder characterized by tetraphocomelia
and bilateral clet lip and/or palate. he limb reductions are
most prominent in the upper extremities. Typically it is associated
with premature separation of the centromere and homozygous
or compound heterozygous mutation in the ESCO2 gene.
Other conditions associated with radial ray abnormalities
include trisomies 18 and 13, the VACTERL association,
acrorenal syndrome, Cornelia de Lange syndrome, Goldenhar
syndrome, Nager acrofacial dysostosis, and Klippel-Feil
syndrome.
Amniotic Band Sequence
Amniotic band sequence is suspected to be secondary to irsttrimester
rupture of the amnion, resulting in amniotic bands
that extend from the chorionic surface of the amnion to the fetal
tissue. 94,95 he incidence is approximately 1 in 1200 live births
but is much higher in spontaneous abortions. Depending on the
timing and orientation of the bands, the resultant disruption of
fetal organs includes amputations of limbs or digits (Figs. 40.30
and 40.31), bizarre facial or cranial cleting, and thoracoabdominal
schisis. he distribution is asymmetrical. Constriction
ring defects are the most common inding. Fibrous bands of
tissue with a constricting ring and distal elephantiasis or protrusion
of uncovered bone distally are pathognomonic for this
anomaly (Fig. 40.32). Antenatally, an aberrant band attached to
the fetus, with characteristic deformities and restriction of motion,
permits the diagnosis. An amniotic sheet is a synechia, or scar
in the uterus, and is distinguished from an amniotic band by a
thickened base and a free edge. 96 Synechiae are not associated
with amniotic band sequence.
he limb–body wall complex is a sporadic disorder that
occurs in approximately 1 in 4000 births with a similar, but
more severe and lethal, complex of fetal malformations. 97
Additional indings include evisceration of internal organs,
myelomeningocele, marked scoliosis, and short straight
umbilical cord.
Caudal Regression Syndrome and
Sirenomelia
Caudal regression syndrome consists of partial to complete sacral
agenesis and abnormalities of the lumbar spine, pelvis, and lower
limbs. 98-100 he majority of cases are associated with maternal
diabetes, but familial cases have been reported. Sirenomelia is
characterized by an absent sacrum, fusion of the lower extremities,
anorectal atresia, and renal dysgenesis or agenesis (Fig. 40.33).
Severe oligohydramnios and single umbilical artery are typically
present. Prevalence is approximately 1 in 60,000 births.
Arthrogryposis Multiplex Congenita
Arthrogryposis multiplex congenita is etiologically a heterogeneous
group of disorders with multiple joint contractures of
prenatal onset 101 (Fig. 40.34). Normal fetal motion by approximately
7 or 8 weeks onward is required for development of the
musculoskeletal system, and the lack of movement results in
joint contractures. Some cases result from extrinsic causes,
such as oligohydramnios, twinning, or uterine masses, and
most of these have a good prognosis. Intrinsic causes include
neuromuscular disorders (most cases) and skeletal and connective
tissue disorders. Typically, the severity of the deformity
increases distally, with maximal deformity in the hands and feet.
his may result in the “Buddha position” of the fetus, with
arms and legs crossed and ending in clubhand or clubfoot (Fig.
40.34D). he fetal akinesia sequence refers to the combination
of decreased or no fetal movements, multiple joint contractures,
in most cases IUGR, underdevelopment of the bones, pulmonary
hypoplasia, typical craniofacial abnormalities, and a short
umbilical cord.