Diagnostic ultrasound ( PDFDrive )

CHAPTER 38 The Fetal Gastrointestinal Tract and Abdominal Wall 1315
Aneuploidy. he conirmation of hyperechogenic bowel on
second-trimester ultrasound requires careful evaluation of the
fetus because of the association with chromosomal abnormalities
(Fig. 38.16A). In most series, fetuses with chromosomal abnormalities
are likely to have other abnormal sonographic indings. 109
he risk of aneuploidy in fetuses with echogenic bowel as an
isolated inding is 1.4% to 6.7%. 109-111 In a study of 281 fetuses
with echogenic bowel, the rate of chromosomal abnormalities
was 6.7% in cases of isolated echogenic bowel compared with
17.4% in cases of echogenic bowel accompanied by major
anomalies.
he most common chromosomal disorder associated with
echogenic bowel is trisomy 21 110,111 ; in a recent meta-analysis of
second-trimester markers for trisomy 21, echogenic bowel was
associated with a positive likelihood ratio of 11.4 for trisomy
21. 112 he reason for the association between trisomy 21 and
Conditions Associated With Echogenic Bowel
FIG. 38.15 Echogenic Bowel. Transverse image through fetal pelvis
shows bowel loops (arrow) that are as echogenic as bone (arrowheads
on ischial tuberosities). The image was obtained with the 4-MHz vector
transducer and harmonics turned off. See also Video 38.8.
Aneuploidy—mainly trisomy 21; less commonly trisomies
13 and 18, 45,X0, triploidy
Cystic ibrosis
Intraamniotic bleeding—swallowed blood (placental
hemorrhage, postprocedural)
Fetal infection—CMV, parvovirus B19, varicella, herpes
simplex, toxoplasmosis
Gastrointestinal tract atresias, obstructions, dysmotility or
stasis
Fetal growth restriction
Fetal anemia
Fetal demise
E
I
A
B
EB
C
Stomach with
debris
FIG. 38.16 Echogenic Bowel. (A)
Transverse fetal pelvis at 18 weeks
in a fetus with trisomy 21 and duodenal
atresia shows echogenic bowel
(arrow E). The image of the bowel is
taken in a plane to include iliac crest
(arrow I) for comparison. (B) Echogenic
bowel (arrows) in fetus with cytomegalovirus
infection. (C) Echogenic
bowel (arrow EB) in fetus with previously
seen subchorionic hemorrhage.
Note small amount of debris
in stomach.