A pregnant woman (gravida 2 para 1 with 1 live issue) was referred to our department for routine obstetrical ultrasound. There was no family history of any birth defects. Her ﬁrst child was healthy. According to dates, the fetus was 31 weeks gestation. On ultrasound scanning, she had a single live intrauterine fetus with cephalic presentation of 32 ± 3 weeks by fetal biometry
Sonal Krishan, MD; Ravi Solanki, MD; Sumer Kumar Sethi,
Department of Radiodiagnosis, Lady Hardinge Medical College and
Associated Hospitals, New Delhi, India.
A pregnant woman (gravida 2 para 1 with 1 live issue) was
referred to our department for routine obstetrical ultrasound.
There was no family history of any birth defects. Her first child
was healthy. According to dates, the fetus was 31 weeks gestation.
On ultrasound scanning, she had a single live intrauterine fetus
with cephalic presentation of 32 ± 3 weeks by fetal biometry
Congenital esophageal atresia (CEA)
On ultrasound, amniotic fluid appeared to be a higher volume
than expected for gestational age. Fetal stomach bubble was not
visualized during the 45-minute sonographic examination (Figure 1).
Fetal skull, spine, bilateral kidneys, and urinary bladder were
normal. All four fetal limbs were identified, and there was no
evidence of radial atresia (not shown). On a coronal ultrasound
scan of the fetal neck, a transient anechoic tubular area was
observed in the midline in the fetal neck, which seemed to distend
during fetal swallowing (Figure 2).
The patient had a spontaneous delivery at gestational week 36.
The baby was diagnosed as having esophageal atresia (EA) with the
"coil-up sign" within the dilated blind-ending esophagus on the
plain postnatal chest X-ray (Figure 3) and required immediate
surgical treatment for respiratory distress. The operation was
uneventful, and the patient was discharged in satisfactory
condition. At 8-month follow-up, the child appeared to be
developing normally and could be fed regularly.
Prenatal ultrasonographic suspicion of EA is usually based on
the presence of both polyhydramnios and a fetal stomach that is
either absent or shows reduced filling.
The ultrasound diagnosis is difficult because there is often a
tracheoesophageal fistula that allows passage of fluids and
consequently causes stomach distension. Even in cases of atresia
without fistula, a moderate distension may occur as a consequence
of gastric secretion.
None of these criteria is definite. Furthermore, when the diagnosis
is based on these two signs, the outcome cannot be predicted before
birth. In a study by Stringer et al
the positive predictive value of an absent stomach bubble and
polyhydramnios was 56%. There are numerous other causes than EA of
an absent or small fetal bubble. These are largely related to
impaired fetal swallowing due to mechanical obstruction, facial
clefts, central nervous system abnormalities and neuromuscular
Prenatal diagnosis of EA enables parents to be prepared for the
birth and treatment of their affected child, permits prompt
neonatal management, and may lead to earlier identification of
associated anomalies (eg, VACTERL association). Important clues
include radial atresia, vertebral defects, and renal anamolies.
Eyheremendy et al
originally reported 2 cases of EA with antenatal ultrasonographic
findings of an alternating filling and emptying of a large proximal
esophagus. Satoh et al
extended these preliminary findings to all cases with both
polyhydramnios and a small or absent stomach bubble. Eight of 10
such cases having an anechoic area in utero were confirmed
postnatally to have CEA. These findings were consistent with our
case. Based on postnatal findings, these 8 cases with an anechoic
area in the neck had either Gross type A or type C CEA. Our case
had type A CEA. Both of these types have a proximal pouch. The
anechoic area in the neck presumably indicates transient fluid
pooling in the proximal pouch of the esophagus derived from the
swallowing of amniotic fluid. Kalche et al
found that a pouch with a base situated within the thorax was
always associated with distal tracheoesophageal fistula and primary
esophageal repair. They also illustrated that a neck pouch was more
likely to be associated with a long atretic gap.
For optimal visualization, the fetal neck should be imaged in a
coronal plane. The ultrasonographic transducer is maneuvered so
that hypopharynx, larynx, and trachea are visible in the same
image. As the transducer is moved posteriorly, the trachea
disappears from view and the esophageal region becomes visible. A
cystic pouch is discernable in the region of the esophagus and is
seen periodically to fill and empty in accordance with fetal
Shulman et al
state that a systematic multiplanar imaging of fetal upper body is
a prerequisite for diagnosing EA. A sagittal view is recommended
for visualizing a low-level pouch, and coronal views are optimal
for revealing a high pouch.
However, not all fetuses with CEA will have a positive neck
pouch sign. In a case reported by D'Elia et al,
no fetal neck pouch was detected although the patient had type C
CEA on postnatal follow-up. Therefore, further studies are
necessary to clarify the independent diagnostic value of the fetal
neck pouch sign. In addition, further investigations are needed to
elucidate the diagnostic value of this anechoic area in the
antenatal diagnosis of type B, D, and E CEA, which have a fistula
between the proximal pouch of the esophagus and either the trachea
or the distal pouch. It has also been suggested that CEA may be
associated with abnormal esophageal peristalsis.
Fetal neck pouch sign may not be discernable in such cases.
Earliest reported suspicion of EA was raised in the 22nd week of
pregnancy in the presence of a small stomach bubble associated with
a persistent left superior vena cava.
Kalache et al
have postulated that difficulty in detecting the pouch sign before
the 26th week, even in the most common type of EA (Type C), is due
to the fetus's inability to generate sufficient pressure when
swallowing to permit dilatation of blind-ending esophagus.
Any anechoic area in the fetal neck must be differentiated from
other diseases, such as cervical cystic hygroma, cystic teratoma,
or thyroglossal cyst. The anechoic area, however, can be easily
differentiated from these anomalies by its transient appearance, as
well as its position.
Trisomy 18 was present in almost half of the fetuses in the
series reported by Stringer et al.
If a fetal sonogram suggests the presence of EA, karyotyping should
also be considered, particularly if additional anomalies are
However, karyotyping was not done in our case.
Fetal magnetic resonance imaging (MRI) has recently been added
to the armamentarium of radiologists, guiding prenatal diagnosis
and management. Langer et al
evaluated the accuracy of fetal sonography followed by MRI for the
diagnosis of EA. Fetuses considered to be at risk for EA, based on
detailed obstetric sonography, underwent MRI. They found that
sensitivity of MRI was 100% and specificity was 80% in prenatal
diagnosis of EA. They concluded that MRI appears to be accurate for
establishing or ruling out a prenatal diagnosis of EA and should be
considered in fetuses that are at high risk based on ultrasonic
Prognosis of a fetus with a suspected EA must be guarded and is
influenced by many factors, including the presence of other fetal
anomalies, results of fetal karyotyping, and diagnostic accuracy of
prenatal ultrasonography. Although it is difficult to determine the
individual prognosis, the high probability of fetal neck pouch sign
may assist in deciding perinatal management. Further, fetal MRI
could be carried out in suspected cases to confirm ultrasonographic
findings. Although recent ultrasound techniques have improved their
diagnostic value for EA, further studies are required to prevent
the many false positives and false negatives that may cause
difficulty in the proper counseling of these patients.