NEONATAL BOWEL OBSTRUCTION DIAGNOSIS
Category: Child Health
Abstract : 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
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.
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