Anemia of Prematurity - Portal Neonatal

The prenatal diagnosis of a bowel obstruction may directly improve postnatal outcome by expediting
its surgical management. Immediate surgical intervention may be needed in patients with congenital
diaphragmatic hernia, esophageal atresia, or malrotation with volvulus. Many children with a
prenatal diagnosis of bowel obstruction are referred for delivery in a center where pediatric surgeons
are readily available.
In situations where prenatal imaging has been used to diagnose an anatomic cause of bowel
obstruction, focused resuscitation in the delivery room may facilitate preoperative stabilization. If
positive pressure respiratory support is needed, rapid intubation without prolonged bag-mask
ventilation may minimize bowel distention and improve outcome. A child born with a possible bowel
obstruction should undergo immediate nasogastric decompression because progressive bowel
distention from swallowed air may cause further compromise. Fluid sequestration in a dilated loop of
obstructed bowel may require aggressive parenteral fluid administration to maintain the patient's
hemodynamic stability. Preoperative laboratory studies, antibiotics, and vitamin K may also be an
appropriate part of the delivery room resuscitation.
PREOPERATIVE WORKUP AND DIFFERENTIAL DIAGNOSIS
OF NEWBORN BOWEL OBSTRUCTION
Section 4
of 11
The diagnostic evaluation of a neonatal bowel obstruction must be expeditious because some
causes of bowel obstruction rapidly cause ischemia leading to necrosis and bowel death. Bilious
vomiting is perhaps the most common symptom that initiates an emergent workup for bowel
obstruction. Physical signs, such as abdominal distention or tenderness, abdominal wall erythema, a
palpable mass, or visible loop of bowel, also demand further investigation. In some situations, an
exploratory laparotomy is the best diagnostic test. Most infants pass meconium in the first 12-24
hours after birth. No newborn should be discharged from the hospital before passing meconium.
The pattern of bowel gas on plain radiography can be used to differentiate between proximal and
distal bowel obstruction. Duodenal atresia, a common cause of proximal small-bowel obstruction,
often creates a double bubble sign on plain radiographic examination. A dilated stomach and
obstructed duodenum, indented at the waist by the pylorus, produces this characteristic
appearance. Plain radiography revealing malrotation with midgut volvulus may show a bowel gas
pattern in the duodenum with an abrupt cutoff in the distal duodenum. A bird's beak sign may be
observed. Radiography of jejunal atresia may also show a few dilated proximal loops of bowel with
no distal bowel gas. If many nondilated loops of bowel are gas-filled but no air is observed in the
rectum, a more distal cause of bowel obstruction is suggested.
Ultrasonography can be helpful in making the diagnosis in newborns with a palpable abdominal
mass. Tumors, intestinal duplication, mesenteric cysts, ovarian masses, or cystic lymphatic
malformations may be identified by ultrasonography. A mass in the inguinal region may represent an
incarcerated inguinal hernia. The use of upper GI series, ultrasonography, and contrast enema are
discussed below in the context of each specific cause of bowel obstruction.
An ileus, or functional bowel obstruction, may result from causes other than those requiring surgical
intervention. Premature infants frequently demonstrate abdominal distention because of small
amounts of subcutaneous fat making the abdominal wall more distensible and because of immature
peristaltic function. Abdominal distention may also be the first sign of necrotizing enterocolitis, a
particularly ominous disease process that can cause death in a neonate. Ileus can also be a
symptom of neonatal sepsis, as well as a result of a central nervous system (CNS) lesion such as
hydrocephalus or a subdural hematoma. Polycystic kidney disease may mechanically obstruct the
bowel as well as predispose to an ileus. Metabolic disorders, such as hypothyroidism, are rare
causes of chronic neonatal ileus that can masquerade as bowel obstruction for several months
before the definitive diagnosis is made. Hirschsprung disease, the absence of ganglion cells in the
distal bowel, can also cause chronic obstructive signs until the definitive diagnosis is finally made by
rectal biopsy.