Anemia of Prematurity - Portal Neonatal

demonstrate the normal fixation pattern to the right and left paracolic gutters. Ultrasonography may
also be helpful in confirming the diagnosis. Normally, the superior mesenteric artery (SMA) lies to the
left of the superior mesenteric vein (SMV). An SMA that lies to the right or anterior to the SMV
suggests malrotation. Contrast enema may demonstrate the abnormal position of the cecum but is no
longer considered the best study to establish the diagnosis of malrotation.
Malrotation with midgut volvulus is a true surgical emergency in the newborn. Delay in operation may
result in catastrophic loss of a large portion of the small bowel. In patients with severe midgut volvulus,
the entire midgut is necrotic and the child cannot survive. Surgical treatment for malrotation is the
Ladd procedure. A Ladd procedure includes evisceration of the midgut and immediate
counterclockwise derotation of the gut to release the volvulus and reestablish flow of blood to the
bowel. Obstructing Ladd bands from the colon to the duodenum are released.
The position of the mesentery does not allow the bowel to be placed in a normal position within the
abdomen; therefore, the bowel is returned to the abdomen in a manner that spreads out the
mesentery as much as possible. The duodenum and small bowel are placed on the right side of the
abdomen, and the colon is placed on the left, with the cecum in the left lower quadrant. Because the
ileocecal valve now is on the left side of the abdomen, the appendix is removed. Development of new
postoperative adhesions may secure the bowel in this new configuration to avoid recurrent volvulus.
Morbidity and mortality from malrotation and volvulus are directly related to the extent of bowel
necrosis. The mortality rate may be as high as 65% if more than 75% of the small bowel is necrotic at
the time of laparotomy. Survivors may develop short bowel syndrome, with its associated
complications of malabsorption and malnutrition. The Ladd procedure does not address the intestinal
dysmotility associated with malrotation but rather prevents the risk of midgut volvulus. Thus, patients
with constipation and motility problems from malrotation may not note improvement in their symptoms
following the Ladd procedure.
Duodenal atresia
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