Diagnostic ultrasound ( PDFDrive )

1408 PART IV Obstetric and Fetal Sonography
A
B
FIG. 40.38 Achondroplasia and the “Trident Hand” Coniguration. (A) Homozygous achondroplasia with trident coniguration with the digits
ending at the same level (yellow line), with inability to approximate the second, third, and fourth digits (pink lines). (B) Homozygous achondroplasia
with ultrasound appearance of severe brachydactyly with trident coniguration.
uteroplacental insuiciency. Triploidy is an exception, occurring
with a severe asymmetrical form of IUGR.
Trisomy 21 (Down syndrome) is the most common chromosome
abnormality in newborns, with an incidence of 1 in 600
to 1 in 800. About 95% of such cases result from an additional
chromosome 21, 3% result from translocation, and 2% are mosaic.
Most cases are sporadic and there is an association with advanced
maternal age. Characteristic skeletal indings include mild
shortening of the femur and humerus, clinodactyly of the ith
inger, sandal gap toes, lat nasal bridge, frontal bossing, and
brachycephaly.
Trisomy 21: Musculoskeletal Features
Mild shortening of femur and humerus
Clinodactyly of ifth inger
Sandal toes
Flat nasal bridge
Frontal bossing
Brachycephaly
Trisomy 18 (Edwards syndrome) is a sporadic condition, in
most cases associated with advanced maternal age and with an
incidence of 1 in 5000 live births. he classic appearance is a
persistently clenched hand with overlapping of the second and
third digits and the fourth and ith digits, oten in association
with clinodactyly of the ith digit. he indings are usually bilateral
and occur in more than 50% of trisomy 18 cases. Other musculoskeletal
indings include radial ray defect in 10% to 50%, syndactyly
of the second and third toes, single palmar creases,
clubfoot or rocker-bottom foot, incomplete clavicle ossiication,
and vertebral and rib anomalies. he prognosis is poor; 90% of
neonates succumb in the irst year of life, and all survivors have
profound mental retardation.
Trisomy 18: Musculoskeletal Features
Persistent clenched hand with overlapping digits
Radial ray aplasia variants
Syndactyly
Talipes equinovarus (clubfoot)
Rocker-bottom foot
Vertebral and rib anomalies
Trisomy 13 (Patau syndrome) is in most cases a sporadic
disorder with an incidence of 1 in 10,000 live births. he
musculoskeletal anomalies include postaxial polydactyly of hands
and feet, possible clenched hand (with or without overlapping
digits), clinodactyly, and possibly associated hypoplastic ribs and
pelvic bones.
Trisomy 13: Musculoskeletal Features
Polydactyly
Persistent clenched hand with or without overlapping
digits
Clinodactyly
Hypoplastic ribs and pelvic bones
Microcephaly
Hypotelorism
Facial clefts
Triploidy (69,XXX, 69,XXY, or 69,XXY) occurs in 18% of all
early miscarriages, but the incidence is only 1 in 2500 births. In
60% of cases, triploidy results from dispermy, and in 40%, from
diploid sperm or diploid egg. Early severe asymmetrical IUGR
and oligohydramnios suggest the diagnosis. he placenta may be
either small or enlarged and hydropic. Associated musculoskeletal
indings include syndactyly of the third and fourth ingers, simian
crease, talipes equinovarus, and hitchhiker toe deformity.