Diagnostic ultrasound ( PDFDrive )

1308 PART IV Obstetric and Fetal Sonography
S
A
B
FIG. 38.4 Dilated Stomach. (A) Dilated fetal stomach (S) in the second trimester. In sagittal view the stomach is visible extending inferiorly
into the pelvis. Although this fetus had a persistently dilated stomach during an anatomic survey, it resolved by the next ultrasound, and the fetus
had a normal outcome. (B) Pyloric stenosis. Transverse ultrasound in 32-week fetus shows a dilated stomach (St) with prominent sustained contraction
of the pylorus (arrow).
S
A
B
FIG. 38.5 Stomach in Abnormal Location. (A) Midline stomach in fetus with heterotaxy. Transverse view of the abdomen shows a midline
stomach (arrow). This was the only abnormality seen at time of fetal survey; fetal echocardiogram revealed anomalous pulmonary venous return,
and the diagnosis of heterotaxy was conirmed postnatally. (B) Heterotaxy syndrome with right-sided stomach. Coronal T2-weighted fetal magnetic
resonance image (MRI) at 34 weeks shows left-sided liver and right-sided stomach (St). The cardiac apex (arrow) is directed left. B, Bladder.
Intraluminal Gastric Masses
he presence of irregular echogenic content or debris within
the fetal stomach can oten be seen on routine ultrasound exams
(Fig. 38.7, Videos 38.2 and 38.3). his inding is nonspeciic and
when found in isolation it is most likely to be a normal inding.
Such debris most oten represents blood, skin cells, or meconium
swallowed by the fetus. 29-32
Small Bowel and Colon
In the irst trimester and early in the second trimester, the small
and large bowel appear somewhat heterogeneous, with an
echogenicity similar to that of the liver. Later in pregnancy, luid
can be seen in the small bowel loops, and meconium can be
seen in the colon. Most cases of GI atresia are thought to represent
a failure of recanalization of the bowel lumen, which is a solid
tube early in fetal life.
Bowel Obstruction
Duodenal Obstruction. Dilatation of the duodenum resulting
from duodenal stenosis or duodenal atresia is the most common
type of bowel obstruction in the fetus, occurring in 1 or 2 per
10,000 live births. 33-35 Duodenal atresia may result from failure
of recanalization of the duodenal lumen, periampullary obstruction,
complete absence of a duodenal segment, or vascular
ischemia. 36-39 Less commonly, duodenal obstruction may be
secondary to mechanical factors such as annular pancreas,
superior mesenteric artery syndrome, or volvulus. 40,41
Associated anomalies are common and are present in more
than half of cases 42 ; most notably, 30% to 44% of cases of
duodenal atresia are associated with trisomy 21. 33,43 Familial
cases of duodenal atresia have also been reported. 44 Duodenal
atresia is also associated with anomalies of the VACTERL
spectrum. 45,46