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DUODENAL ATRESIA IN THE NEWBORN
Category: Child Health
Abstract : Duodenal atresia in the newborn : Duodenal obstruction from atresia or web
affects as many as 1 in 6,000-10,000 infants. Polyhydramnios is present in as
many as 50% of fetuses with duodenal obstruction and frequently leads to
prenatal diagnosis of duodenal atresia. This polyhydramnios may lead to fetal
distress and premature delivery in one third of patients. Vomiting, abdominal
diste
Duodenal atresia in the newborn :
Duodenal obstruction from atresia or web
affects as many as 1 in 6,000-10,000 infants. Polyhydramnios is present in as
many as 50% of fetuses with duodenal obstruction and frequently leads to
prenatal diagnosis of duodenal atresia. This polyhydramnios may lead to fetal
distress and premature delivery in one third of patients.
Vomiting, abdominal
distention, and a dilated loop of bowel on plain radiography are consistent
features of duodenal atresia or web. Some atresias may be obstructing
incompletely; in these situations, a small amount of distal bowel gas may be
observed on plain radiography. Duodenal atresia is believed to occur from a
failure of revacuolization of the lumen of the duodenum at 8-10 weeks'
gestation.
At earlier phases in fetal development, the lumen of the
duodenum is obliterated by the proliferation of the layers of duodenal wall.
Beginning at 8 weeks' gestation, a lumen is regenerated in the previously solid
duodenum. If this process is incomplete, an atresia or web may occur.
Duodenal web results from an obstructive band of mucosa that stretches
across the duodenal lumen. These webs may be incomplete, or a web may stretch
out distally in the lumen of the duodenum like a windsock. Duodenal atresia may
also occur from an improper rotation of the pancreas to the right of the
duodenum and may be associated with an annular pancreas. Development of duodenal
atresia follows a different embryologic pattern from that of jejunoileal
atresias. Unlike jejunoileal atresias, which are believed to result from a
mesenteric accident, in patients with duodenal atresia, the mesentery of the
duodenum is intact.
The finding of duodenal atresia suggests an early
error in development, and duodenal atresia may be associated with other
congenital anomalies in as many as 50% of patients. Associated disease processes
include trisomy 21 (40% of patients), imperforate anus, and congenital cardiac
disease.
An infant with duodenal atresia may present with bilious or
nonbilious vomiting. If a complete duodenal atresia or web lies upstream of the
ampulla of Vater, the vomiting is nonbilious. In 85% of patients
with
duodenal atresia, the obstruction lies distal to the ampulla or is
incomplete. In these situations, vomiting is bilious. The abdomen is usually
distended by the dilated duodenal loop but may be scaphoid if the obstruction is
incomplete. Preoperative treatment for these patients includes fluid
resuscitation and nasogastric decompression.
Consultation with a
cardiologist and echocardiography may be helpful because of the high incidence
of associated anomalies. If the obstruction is incomplete as evidenced by some
distal gas on plain radiography, urgent laparotomy may be necessary to
differentiate duodenal atresia from malrotation with volvulus. Surgery involves
resection or bypass of the atretic segment. A web must be identified and
completely resected to the degree that it no longer obstructs the distal
lumen.
Many pediatric surgeons bypass rather than resect the atretic
segment to avoid injury to the ampulla or to the pancreatic blood supply that
usually is nearby. A severely dilated duodenum may require a tapering
duodenoplasty to mitigate the poor long-term duodenal motility that can be
observed in these dilated proximal segments. A nasoenteric feeding tube is often
placed across the duodenal anastomosis for early decompression and late feeding.
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