Congenital intestinal atresias, stenosis, and webs typically present
early in neonatal life due to the associated obstructive symptoms.
The reported incidence varies from 1 to 2 in 5000 births in the United
States. These malformations can occur throughout the intestinal
tract, but are most commonly found in the duodenum (50%)
and the jejunum or ileum (35–40%). A colonic location
is identified in 5% to 10% of atresias, and rarely,
pyloric or gastric lesions are present (< 1%).1
The etiology most commonly accepted for jejunoileal and colonic
atresias involves intrauterine mesenteric ischemia from a variety
of vascular accidents, encompassing umbilical cord infarcts, volvulus,
internal hernias, fascial defects, intussusception, and intestinal perforation.
The affected segment is then reabsorbed. In contrast, duodenal atresia
is attributed to a failure of the recanalization process. Genetic
links and familial patterns of intestinal atresias (mostly autosomal
recessive) are also well described, although the specific genes or
mutations involved have yet to be identified. Duodenal atresia is
associated with anomalies including trisomy 21, congenital heart
disease, malrotation, esophageal atresia, imperforate anus, genitourinary
disorders, and gallbladder agenesis. Recently, an autosomal recessive
syndrome comprising neonatal diabetes mellitus, intestinal atresias,
and gallbladder agenesis has been described.2 An
autosomal recessive genetic disorder called Herlitz syndrome is
linked to some cases of pyloric atresia. Patients with this syndrome
suffer from epidermolysis bullosa lethalis, which results in severe
vesiculobullous lesions after minimal skin friction.
Clinical Features, Diagnosis,
The majority of infants with intestinal atresia present as newborns
with signs and symptoms of intestinal obstruction (see Chapter 389), including vomiting (which may be bilious), varying degrees
of abdominal distension, and often failure to pass meconium. Antenatal diagnosis
has been reported, facilitating prompt postnatal diagnosis and management
but without proven impact on long-term outcome.3
Antral and Pyloric
Atresia and Webs
Antral or pyloric atresias and webs are rare lesions that present
typically with nonbilious emesis and failure to thrive.4 Unlike
acquired hypertrophic pyloric stenosis, these neonates present with
polyhydramnios in utero and an enlarged stomach at the time of birth.
Partial antral and duodenal webs can also present with chronic vomiting,
often commencing upon the advent of solid feedings, due to intermittent
or partial obstruction.5 The most common abnormality
is a pyloric web, which is a membrane that can become redundant over
time and prolapse into the pyloric channel, creating a classic “windsock” finding.
Diagnosis of pyloric atresia typically requires an upper GI contrast
study and/or endoscopy. Following adequate fluid resuscitation
and gastric decompression, treatment includes laparotomy followed
by pyloroplasty, gastroduodenostomy, or primary anastomosis, depending on
the type and severity of the lesion. Endoscopic laser treatment of
an antral web has been reported.6
Duodenal atresia and webs account for half of all intestinal
atresias. In contrast to jejunoileal atresias, duodenal lesions
are more commonly associated with other anomalies, occurring in
50% to 80% of cases.1 As described
for pyloric lesions, there are 3 types of atresias in the duodenum,
with equal distribution between the incidence of webs and atresias.
The usually presentation is bilious vomiting in the newborn. Incomplete
obstruction from a fenestrated web (with or without a windsock)
or stenosis may have a delayed presentation. Prenatal imaging along
with polyhydramnios may suggest the diagnosis, but it is confirmed
with an X-ray at birth revealing the classic double-bubble sign
(air in both duodenal bulb and stomach as shown in Fig.
399-1). With complete duodenal obstruction, no distal gas will
be seen and no further imaging is warranted. If an incomplete obstruction
is present, distal gas may confuse the diagnosis with malrotation,
and thus an upper GI contrast study should be performed. If malrotation
is ruled out, other associated anomalies can be evaluated before proceeding
to the operating room. The vast majority of duodenal malformations
occur distal to the ampulla of Vater, and hence, great care must
be taken to avoid injury to the biliary system intraoperatively.
The surgical procedure of choice is a Kimura diamond duodenoduodenostomy.
Duodenal webs are managed with incision or partial excision through
a duodenotomy. Postoperatively, nasogastric decompression is sufficient while
awaiting bowel function return and normal gastric emptying.
Double-bubble sign on plain radiography in patient with
Jejunoileal atresia occurs far more commonly than jejunoileal
webs (90% vs 10%). In contrast to pyloric, duodenal,
and colonic atresia, other anomalies are rarely associated with
jejunoileal atresia. The classification system used for other intestinal
atresias is expanded to include type 3a (eFig.
type 3b, and type 4 atresias, unique types seen in the small intestine
as shown diagramatically in Figure 399-2.7,8 Infants present with
bilious vomiting and abdominal distension. They may or may not pass
some meconium. Plain films will demonstrate multiple dilated bowel
loops. Contrast studies from above and below aid in diagnosis. The
classic “microcolon” seen on contrast enema suggests
a more proximal complete small intestinal obstruction (eFig.
resuscitation and operative intervention are necessary. The surgical
repair chosen depends on the type of atresia present.9 Other
atresias should be excluded intraoperatively, with irrigation of the
proximal and distal bowel. The surgeon must evaluate the blood supply,
bowel length present, and diameter of proximal and distal lumens
to determine the most appropriate operation. Preservation of bowel
length is the goal of reconstruction. Primary anastomosis is preferred,
with or without a tapering enteroplasty.10 Patients
with shortened bowel length may require support with parenteral
nutrition. In some cases, stomas and bowel-lengthening procedures
may be required.
Photograph of a type 3a intestinal atresia.
Classification of intestinal atresias. Type I is a membrane
or web, type II is an atretic segment with a solid cord between
the two ends, and type III is atretic, with a gap between the stomach
and duodenum. Type IIIA refers to the previously described wedge-shaped
gap in the mesentery between 2 blind ends of small bowel. Type IIIB
refers to the “Christmas tree” or “apple-peel” atresia
with an abnormal mesenteric blood supply. This latter type often
results in significant bowel loss as the distal end is corkscrewed
around a marginal artery. Type IV of atresia encompasses the presence
of multiple atresias, which can result in a “string of
Contrast enema demonstrating the classic microcolon in
a patient with jejunoileal atresia.
Colonic atresia is a rare cause of distal bowel obstruction and
can have the same clinical presentation as a small bowel atresia.11 Bilious
emesis, abdominal distention, failure to pass meconium, and absent
distal gas on X-ray, combined with contrast enema findings consistent
with incomplete colonic filling, confirm the diagnosis. Because
colonic atresia can be associated with aganglionosis, a rectal biopsy
should be performed as part of the evaluation. Colonic atresia may
also be associated abdominal wall, skeletal, cardiac, or ophthalmologic
defects. Intraoperatively, the entire intestinal tract must be evaluated for
additional obstructing lesions, as colonic atresia can be associated
with multiple small bowel atresias. Surgical repair is required, which
can be accomplished with segmental resection and either primary
anastomosis or diversion. Recent reports on management of colonic
atresia demonstrate good outcomes of primary anastomosis repairs
when the disparity in proximal and distal bowel diameters did not
exceed a 3:1 ratio.
The overall survival of infants with intestinal atresias, stenosis,
and webs has risen dramatically over the past several decades, mainly
due to advances in neonatal nutrition, anesthesia, and perioperative
care. Before 1950, the mortality rate was greater than 90%,
whereas currently, greater than 90% of infants with these anomalies
survive. Infants with atresias or webs, and other congenital anomalies
are at higher risk of mortality. Atresia location does not affect
mortality, but children with multiple intestinal atresias are more
likely to require prolonged nutritional support.12 Late
complications that require repeat surgical interventions are somewhat
more frequent in patients with duodenal atresia.13 Other
complications include iron deficiency due to gastrointestinal bleeding14 and
bacterial overgrowth, which has been described with persistence
of dilated bowel in some patients who underwent side-to-side anastomosis.