Anemia of Prematurity - Portal Neonatal

Other causes of proximal bowel obstruction
Esophageal atresia and tracheoesophageal fistula
Esophageal atresia is a foregut malformation resulting from an error in separation of the esophagus
from the respiratory tree. Newborn infants with esophageal atresia are unable to swallow their
secretions and present with respiratory distress or an inability to nurse. Inability to pass a nasogastric
tube is diagnostic of esophageal atresia.
The common association of a distal tracheoesophageal fistula predisposes a newborn to aspiration of
acidic gastric contents and respiratory distress. Preoperative management must take into account the
danger of respiratory collapse with positive pressure ventilation because ventilated breaths may
preferentially shunt through the tracheoesophageal fistula into the stomach. Repair of esophageal
atresia involves ligation of the tracheoesophageal fistula and anastomosis of the proximal and distal
ends of the esophagus, if possible.
Occasionally, esophageal replacement with bowel or stomach is necessary. Anastomotic stricture,
gastroesophageal reflux, and poor esophageal motility affect long-term outcome.
Hypertrophic pyloric stenosis
Gastric outlet obstruction from pyloric stenosis results from hypertrophy of the pylorus. This condition
is acquired, although its etiology is not fully characterized. Hypertrophy of the pylorus is associated
with reduced nitric oxide levels in the pyloric muscle tissue. Nitric oxide generally mediates relaxation
of gastrointestinal smooth muscle so that pyloric obstruction may be related to a local reduction of
nitric oxide levels in the pyloric muscle.
Most children with pyloric stenosis present with nonbilious vomiting and dehydration at 4-6 weeks,
although hypertrophic pyloric stenosis can be observed in babies younger than 1 week. The thickened
pylorus muscle is often palpable; ultrasonography and contrast studies may be helpful in diagnosis.
Operative pyloromyotomy is curative.
DISTAL BOWEL OBSTRUCTION Section 6 of 11
In contrast to obstruction in the duodenum or proximal small bowel, patients with a distal bowel or
colonic obstruction often present in the newborn period with subacute clinical and radiographic
features characterized by distention. In most patients with distal obstruction, the bowel is not
immediately in danger of compromise, thus time is available for appropriate workup and diagnostic
studies. Distention, rather than vomiting, is frequently the dominant clinical feature. Imperforate anus
and other anorectal anomalies may be readily diagnosed on inspection of the perineum. Plain
radiographic findings often suggest a distal obstruction with a pattern of proximal air-filled dilated
small-bowel loops but no distal air. In these patients, a contrast enema may be both diagnostic and
therapeutic.
A contrast enema, usually with hyperosmolar Gastrografin (diatrizoate), can help differentiate causes
of distal bowel obstruction. The colonic and distal small-bowel lumen may be obstructed with thick
meconium in patients with meconium ileus. Colon dilated proximal to a thick obstructing mass of
meconium suggests meconium plug syndrome. A contrast enema may demonstrate a transition zone
between small-caliber distal colon and more dilated proximal colon in patients with Hirschsprung
disease. More proximal obstructions can produce a contrast enema picture of a small-caliber colon,
termed congenital microcolon or small left colon syndrome.
Meconium ileus: Meconium ileus is the term used to describe neonatal presentation of distal smallbowel
obstruction from thickened meconium in patients with cystic fibrosis. Meconium ileus is the
earliest manifestation of cystic fibrosis in the newborn period. Cystic fibrosis is an autosomal recessive