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At
the beginning of a pregnancy, the trachea ("windpipe") and
the esophagus ("foodpipe") are one single tube, called the
primitive foregut*. Between the 23 rd and
the 28th day of pregnancy, a time when many women
are not even sure they are pregnant, this single tube divides
into two tubes – the trachea, which takes the air you breathe
to the lungs, and the esophagus, which takes food, water,
and saliva to the stomach.
 
Three week old human embryo during stage 10 of development
23 to 28 days after conception. During this stage the esophagus
and trachea are formed. During this stage the spine is already
developing. If you look close you can see the spine developing.
If
something should ever go wrong with this division, as it
does in approximately one out of every 3,500 – 4,000 births,
the baby is born with a medical condition known as esophageal
atresia and/or tracheoesophageal fistula.
The anomalies are thought to arise from 1) a defective division
of the primitive foregut into the trachea and esophagus,
2) defective growth of the entodermal* cells leading to
atresia, or 3) incomplete fusion of the lateral side walls
of the foregut during separation of the trachea from the
foregut causing a tracheoesophageal fistula.
Atresia means an absence or closure of
an orifice or tubular organ. In this case, the esophagus
has a gap between its upper and lower segments, so that
nothing can pass through, not even saliva. The fistula
is a connection between the esophagus and trachea, which,
depending on its position, either lets food or acidic stomach
juices into the lungs.
When a fetus has esophageal atresia,
the inability to swallow and eliminate amniotic fluid may
result in polyhydramnios.* This is the first sign
of possible atresia at some level in the upper gastrointestinal
tract and may lead to premature birth.
Many babies born with this defect have
other medical problems – all associated with organs that
were being formed during the same period at the beginning
of the pregnancy. At least 25% of these babies are
premature, and 25% have additional critical problems such
as congential heart disease, Down's Syndrome*, hydronephrosis*,
duodenal atresia*, and tracheomalacia*. Ten percent
of the babies have an imperforate anus*, and one-half have
vertebral or skeletal anomalies.
Researchers found that it was not
uncommon to have vertebral (V), anal (A), tracheo-esophageal
(TE), and/or radial limb or renal (kidney)
(R) anomalies, which was abbreviated as VATER syndrome (or
VATER association) by Quan and Smith in 1973. This
syndrome is also currently being termed as VACTERL, the
C referring to cardiovascular problems, and the L to limb
defects, because of the high percentage of children with
VATER syndrome born with these latter anomalies.
How is this anomaly discovered?
In type A atresia, both esophageal segments
are blind pouches, and neither connected to the trachea.
It maybe termed as pure esophageal atresia and may
be considered either short or long gap, depending on the
space between the segments. An infant born with pure
esophageal atresia may appear normal at birth, but as they
swallow, secretions fill the esophageal pouch, causing an
overflow into the oropharynx*, and the infant will drool
excessively.
When the infant is fed, vomiting and respiratory
distress follow (aspiration). Continual suctioning
temporarily relieves these symptoms. Both the excessive
secretions and drooling in a newborn strongly suggest esophageal
atresia.
In type E (or H-type tracheoesophageal
fistula without atresia) the fistula may occur anywhere
between the level of the cricoid cartilage* and the mid-esophagus.
However, the fistula is usually higher in the trachea than
in the esophagus. A fistula such as this may be as
small as a pinpoint.
Symptoms that may signal this H-type fistula
are repeated episodes of lung inflammation (pneumonitis),
infection of the lungs or respiratory system (pulmonary
infection), and swollen abdomen (abdominal distention).
When a child with this disorder drinks, he coughs, chokes,
and becomes cyanotic (bluish discoloration of the skin and
mucous membranes).
The reasons for this are that excessive
mucous builds up in the esophagus, producing abdominal distention.
This type of tracheoesophageal fistula may be overlooked,
since such a child may appear normal at birth. It
is possible for diagnosis to be delayed as long as a year.
In types B and D, the upper portion of
the esophagus opens into the trachea, a life-threatening
condition since an infant with this anomaly can aspirate
saliva or food into the trachea. Both type B (proximal
fistula and type D (fistula to both segments) cause immediate
inhalation of saliva into the trachea airway and bacterial
pneumonitis*.
The
most common tracheoesophageal fistula is Type C, which includes
esophageal atresia. The upper section of the esophagus ends
in a blind pouch, and the lower section ascends from the
stomach and connects with the trachea by a short fistulous
tract.
A newborn with tracheoesophageal fistula with esophageal
atresia appears to swallow normally, but soon after swallowing
coughs, struggles, becomes cyanotic (skin turns blue in
color), and stops breathing since he is inhaling aspirating)
fluid returning from the blind pouch of the esophagus through
his nose and mouth.
In this infant stomach distention may cause respiratory
distress. Also air and gastric contents (bile and
gastric acid secretions) may reflux through the fistula
into the trachea, resulting in chemical pneumonitis*.
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