Diagnostic ultrasound ( PDFDrive )

CHAPTER 38 The Fetal Gastrointestinal Tract and Abdominal Wall 1329
FIG. 38.34 Omphalocele-Exstrophy–Imperforate Anus–Spinal
Defects (Cloacal Exstrophy). T2-weighted MRI of twins. The upper
twin was normal with normal amniotic luid. The lower twin had oligohydramnios
with a lower anterior abdominal wall defect (arrow). See
also Video 38.15.
FIG. 38.35 Ectopia Cordis. Transverse image through the chest on
one of a dichorionic twin pair shows that the liver and heart (arrow) are
external to the thorax. Sp, Spine. This is a lethal malformation, in this
case, caused by amniotic bands, which were visible in real time. The
co-twin was normal and was delivered at term.
probably low and it is likely that many cases of OEIS are misdiagnosed.
Once this diagnosis has been made, genetic counseling
is recommended, and amniocentesis may be considered to identify
gender prior to birth.
Ectopia Cordis
Ectopia cordis is a midline defect of the upper fetal ventral body
wall through which all or part of the heart extrudes, with or
without a membrane (Fig. 38.35). Most commonly the heart
protrudes at the level of the chest through a defect involving the
sternum, but the heart can be located at the cervical or abdominal
region. Association with structural cardiac anomalies or other
abdominal wall defects is common. 236 Prognosis is poor, although
survivors have been reported. 237 Trisomy 18 has been associated
with this diagnosis, especially in the presence of additional
abnormalities. 238,239
Other Complex Body Wall Defects
In cases when the insult during the formation of the ventral
abdominal wall is severe and takes place at an early embryonic
developmental stage, the result is large and/or multiple defects
of the ventral body wall, with evisceration of multiple organs of
the abdomen, chest, and pelvis. hese disorders are oten associated
with other anomalies involving the limbs, urinary system,
external genitalia, and spine. Several syndromes and associations
have been suggested to describe these conditions, each including
diferent combinations of the previously listed defects. However,
given the considerable overlap between these syndromes, it
remains unclear whether they represent distinct pathogenetic
entities or diferent manifestations of a single basic disorder.
his overlap oten results in a signiicant confusion in the terminology
used to describe these conditions.
Pentalogy of Cantrell
Pentalogy of Cantrell is a rare complex disorder of the ventral
body wall that refers to a combination of defect of the sternum,
ectopia cordis, cardiac anomalies (e.g., septal defects, tetralogy
of Fallot, transposition of great arteries), defect of the anterior
diaphragm and diaphragmatic pericardium, and supraumbilical
abdominal wall defect (most commonly omphalocele). 240,241
Other associated anomalies include midline abnormalities such
as facial clet and encephalocele. Given the association with
trisomies 18 and 13, genetic consultation is recommended. Most
of these cases are sporadic, and the risk of recurrence is low.
he prognosis of this disorder is poor. 242
Body Stalk Anomaly
Body stalk anomaly (also known as limb–body wall complex)
is a rare and lethal disorder of the anterior abdominal wall. here
are three hallmarks of this disorder: (1) here is a severe disruption
of the abdominal and thoracic walls. (2) he abdominal and
thoracic organs (e.g., heart, lungs, liver, bowel, bladder) are located
outside the body cavity and are contained within a sac that is
closely attached to the placenta, leading to a relatively ixed
position of the fetus. (3) he umbilical cord is very short or
absent, possibly because of a failure of the body stalk to develop
properly. Associated musculoskeletal abnormalities are common
and include severe kyphoscoliosis and limb defects such as
club foot and absent or malformed limbs. 243-245
he pathogenesis of this disorder is unclear, and several
hypotheses have been suggested, including early vascular disruption,
disruption due to amniotic bands following early amniotic
rupture, or complete failure of the folding process of the embryonic
disc. 246 his disorder is always lethal.