Diagnostic ultrasound ( PDFDrive )

CHAPTER 35 The Fetal Spine 1237
chondriication centers is deicient. he remaining ossiication
center is displaced laterally with respect to the vertebrae above
and below it, leading to a short-segment mild scoliosis. he
abnormalities can be detected prenatally and may be best portrayed
with 3D ultrasound. 31-34 Fetuses with an isolated
Causes of Scoliosis or Kyphosis
Hemivertebrae
Butterly vertebrae
Block vertebrae
Spina biida
Ventral abdominal wall defects
Limb–body wall complex
Amniotic band syndrome
Arthrogryposis
Skeletal dysplasias
VACTERL a association
Caudal regression syndrome
a Vertebral abnormalities, anal atresia, cardiac abnormalities,
tracheoesophageal istula, renal agenesis, and limb defects.
hemivertebra have an excellent prognosis, whereas those with
other fetal anomalies (e.g., Potter syndrome; cardiac, intestinal,
intracranial, and limb anomalies) have a poor prognosis. 110 he
presence of associated anomalies reduces the survival rate to
approximately 50%. If oligohydramnios is also present, the
mortality rate approaches 100%. 111
SACRAL AGENESIS
Sacral agenesis is an uncommon fetal abnormality that may be
present in conditions such as caudal regression sequence,
sirenomelia sequence, cloacal exstrophy sequence, and the
VACTERL association. he caudal regression sequence (caudal
regression syndrome) and the sirenomelia sequence are thought
to be separate pathologic entities. 112,113
CAUDAL REGRESSION
In caudal regression or dysplasia, abnormalities of the lower
spine and limbs occur, including sacral agenesis, lumbar spine
deiciency, and leg anomalies such as femoral hypoplasia (Fig.
35.20). Defects of the neural tube and the genitourinary,
A
B
C
D
FIG. 35.20 Caudal Regression. (A) Sagittal sonogram of spine at 21 weeks shows abrupt termination of ossiied vertebral bodies. (B) Transverse
view of pelvis with legs in long axis shows lack of ossiied pelvic bones and atrophic musculature about the lower extremities. (C) Transverse
color Doppler image at level of bladder shows lack of ossiied pelvic bones. (D) In a different fetal specimen, radiograph shows abrupt termination
(arrows) of the lumbar spine and absence of the sacrum. The pelvic bones are small and deformed.