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Gastrointestinal obstructions are categorized according to etiology
as either congenital or acquired.
These broad categories are not mutually exclusive. For example,
congenital lesions of the intestine such as an enteric duplication
or Meckel diverticulum may not cause obstruction until later in
life. Congenital anatomic defects and acquired disorders of the
intestine presenting in the first 30 days of life are characterized
as neonatal intestinal obstruction.
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Clinical Features
and Differential Diagnosis
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Neonatal Intestinal
Obstruction
++
The anatomic conditions that present with neonatal intestinal
obstruction and their diagnostic features are summarized in Table 389-1. Accurate diagnosis of neonatal
intestinal obstruction relies on a thorough history, careful examination,
and directed radiological studies.1 In a newborn
infant, postprandial nonbilious emesis, or spitting up, is quite
common and does not require urgent evaluation (see Chapter 394). In contrast, neonatal intestinal obstruction is usually
characterized by feeding intolerance, abdominal distention, bilious
emesis, and failure to pass meconium. Bilious emesis is most frequently
a consequence of mechanical intestinal obstruction, and prompt evaluation
is necessary to exclude life-threatening conditions such as necrotizing
enterocolitis or volvulus. The history provides clues to the potential
etiology of intestinal obstruction, but history and physical examination
alone are generally not reliable for establishment of a diagnosis.
For example, a 3-week-old infant with bilious emesis who has passed meconium
and previously tolerated feeding is unlikely to have intestinal
atresia as a cause of emesis and more likely to have intestinal
malrotation with midgut volvulus. Infants with trisomy 21 are more
likely to have congenital duodenal obstruction2 and
Hirschsprung disease. Neonates with anomalies of vertebral, anorectal,
cardiac, esophageal, renal, and limbs are more likely to have esophageal
atresia and anorectal malformations as
possible causes of intestinal obstruction (VACTERL association).
Extremely low birthweight, premature infants are much more likely
than term infants to develop necrotizing enterocolitis.
++
++
Given the widespread practice of prenatal ultrasound, several conditions
such as proximal jejunal atresia and congenital duodenal obstruction
may be diagnosed prior to delivery. The presence of polyhydramnios
on prenatal ultrasound requires careful review for anatomic lesions
causing obstruction of the developing foregut. The prenatal identification
of anatomic intestinal obstruction allows for prospective education
and counseling of parents. Presently, the prenatal ultrasound diagnosis
for more distal intestinal conditions, and in particular, imperforate
anus and Hirschsprung disease, is not reproducibly accurate and
of limited clinical value.3
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Nonanatomic conditions may also lead to clinically significant
feeding intolerance and abdominal distention that may be difficult
to distinguish from anatomic obstruction. In particular, neonatal
sepsis is a common cause of feeding intolerance, emesis, and abdominal
distention. A variety of disorders cause gastrointestinal pseudoobstruction
that mimics mechanical obstruction, but these should be considered
only after careful evaluation for causes of mechanical obstruction (see Chapter 407).
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Intestinal Obstruction
in the Older Infant or Child
++
Table 389-2 lists selected, more commonly
encountered causes of intestinal obstruction occurring in older
infants and children. Consideration of the age of the infant or
child is useful because the more common causes present at characteristic
ages. Additionally, there are symptoms and signs characteristic
of childhood diseases causing anatomic intestinal obstruction. The
constellation of a history, examination, and clinical knowledge
allow a pediatrician to form a rational approach to the use of appropriate
diagnostic tools and development of a therapeutic plan for intestinal
obstruction.
++
++
Volvulus from intestinal malrotation is more
common in the first week to year of life but may occur at any age.
Prompt diagnosis of volvulus mandates a high degree of clinical
suspicion in any infant or child with bilious emesis. Emergent diagnosis
of volvulus by upper gastrointestinal contrast study in a hemodynamically
stable child without peritonitis is critical for successful outcome.
However, it is important to recognize that intestinal obstruction
from volvulus may occur in the absence of bilious emesis as well.
++
Progressive, postprandial, and nonbilious “projectile” emesis
in a 1- to 2-month-old male infant previously tolerant of feeding
suggests a diagnosis of hypertrophic pyloric stenosis (see Chapter 398). Infants with pyloric stenosis
are often initially diagnosed with gastroesophageal reflux or formula
intolerance, and as the pylorus becomes progressively more hypertrophic,
symptoms of gastric outlet obstruction worsen. A careful history
reviewing the timing and nature of the emesis and an examination
of the abdomen with the infant’s legs raised to relax abdominal
musculature may allow for palpation of the hypertrophied pylorus. Lethargy,
feeding intolerance, emesis, and hematochezia (“currant-jelly” stools)
in a 6-month to 3-year-old child is characteristic of intussusception. Careful
clinical examination will detect a palpable mass in the majority
of infants with intussusception, and plain films may demonstrate
an obstructive bowel gas pattern if symptoms have been present for
more than 1 day. A previous history of neonatal necrotizing enterocolitis, inflammatory
bowel disease, or abdominal operations in an older child with suspected gastrointestinal
obstruction increases the probability of obstruction from either intestinal
stricture or intra-abdominal adhesions.
++
Perforated appendicitis and Hirschsprung
disease both may present with obstructive symptoms. Many
children with perforated appendicitis present with a several-day
history of unremitting abdominal pain associated with anorexia,
occasional emesis, and reproducible tenderness in the right iliac
fossa. While CT scan has become a popular diagnostic adjunct in
the workup of appendicitis, it has probably not reduced the negative
appendectomy rate in children, and there is significant exposure
to ionizing radiation.4-6 Most children with Hirschsprung
disease are diagnosed during infancy. Occasionally, a child presents
with a long history of constipation, failure to thrive, explosive
stool on digital rectal examination, and obstructive plain films
(see Chapter 407). Additional diagnostic examination,
including retrograde contrast enema, rectal biopsy, and anorectal
manometry, may be useful in the diagnosis of Hirschsprung disease
in older children.
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Diagnostic Evaluation
+++
Neonatal Intestinal
Obstruction
++
Diagnosis of neonatal intestinal obstruction may be made with
careful physical examination and directed diagnostic imaging studies. Figure 389-1 outlines a diagnostic approach
to suspected neonatal intestinal obstruction. Examination of oropharynx,
abdomen, perineum, and anus may help guide the diagnostic evaluation.
The presence, position, and patency of the anus should be confirmed.
Incarceration of an indirect inguinal hernia is a common cause of
neonatal intestinal obstruction and can be easily diagnosed by physical
examination alone. Abdominal distention is commonly observed in
distal bowel obstruction, whereas the abdomen may be scaphoid in
proximal obstruction. For example, infants with ileal atresia or
meconium ileus will present with abdominal distension; in contrast,
infants with clinically evident trisomy 21, feeding intolerance,
and a nondistended or scaphoid abdomen should be evaluated for more
proximal intestinal obstruction, such as duodenal atresia.
++
++
The mainstay of diagnostic imaging for neonatal intestinal obstruction
is a plain abdominal radiograph. Swallowed gas acts as an excellent
contrast media for most neonates, and the degree of abdominal distention
found on examination generally correlates with the amount of intestinal
distention observed on abdominal films. For example, an infant with
duodenal atresia would be expected to have a relatively scaphoid
abdomen; a plain abdominal radiograph will typically demonstrate
a gas-filled stomach and duodenum, creating a “double-bubble” sign,
while the remainder of the unused intestine remains gasless (see Fig. 399-1). More distal intestinal obstruction
will be characterized by greater abdominal distention and gas-filled
loops of intestine proximal to the obstruction. The presence of
pneumatosis intestinalis on plain film in a premature infant with
abdominal distention, feeding intolerance, and hematochezia is diagnostic
for necrotizing enterocolitis.
++
Many causes of neonatal intestinal obstruction that may be diagnosed
by history, examination, and plain films alone. Contrast studies are
particularly useful in suspected distal intestinal obstruction or
for suspected intestinal malrotation. Retrograde contrast enema
studies are helpful for determining the anatomic site of distal
obstruction. Occasionally, contrast enemas are also therapeutic,
for example, in the resolution of meconium plug syndrome or simple meconium
ileus. The finding of a small, unused microcolon on contrast enema
may be observed with more proximal intestinal atresia or complete
obstruction. An upper gastrointestinal series is the diagnostic
procedure of choice in suspected intestinal malrotation to determine the
anatomic location of the duodenojejunal junction (ligament of Treitz)
and to assess whether there is associated volvulus or mesenteric
twisting of the small intestine.4
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Intestinal Obstruction
in the Older Infant or Child
++
Many of the principles outlined for neonates apply to intestinal
obstruction in the older infant or child. The urgency of the evaluation
and specific diagnostic approach usually depend on findings on physical
examination, laboratory results, and plain films of the abdomen.
Ultrasound examination of the pylorus is the diagnostic test of
choice if the history suggests pyloric stenosis and the pylorus
is not readily palpable; however, if the diagnosis is uncertain,
a radiographic upper gastrointestinal contrast study is preferred.
In a child with suspected intussusception and the absence of peritonitis,
a fluoroscopic retrograde enema using either contrast or air is
diagnostic and may be therapeutic in reducing the intussusception
in approximately 60% to 80% of children (see Chapter 404).5 Additional
diagnostic examination, including retrograde contrast enema, rectal
biopsy, and anorectal manometry, may be useful in the diagnosis
of Hirschsprung disease.
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Initial Management
of Intestinal Obstruction
++
Initial management of any infant or child with suspected intestinal
obstruction includes discontinuation of feeding, proximal decompression
of the gastrointestinal tract with orogastric or nasogastric tube,
intravenous fluid resuscitation to euvolemia, and addressing any
coexisting medical or electrolyte issues. Diagnostic imaging may
be accomplished either at the bedside or, if stable, in the radiology
suite. Most causes of neonatal intestinal obstruction are readily
diagnosed by history, examination, and plain abdominal films, with
the remainder diagnosed by retrograde contrast enema. Diagnosis of
intestinal obstruction in the older infant or child requires individualized
adjunctive tests directed by the child’s age, symptoms,
signs, and clinical suspicion.
++
Anatomic lesions causing intestinal obstruction require operative
treatment with variable urgency. While malrotation with midgut volvulus requires
emergent intervention to prevent bowel loss and death, obstruction
due to intestinal atresia is generally repaired electively within
the first few days of life. Prompt evaluation and early surgical
consultation is warranted for any suspected anatomic intestinal
obstruction. If expert pediatric subspecialty surgeons are readily
available, their consultation is preferred. However, if such consultation
is not readily available, emergent evaluation and consultation by
a general surgeon is recommended because a delay in diagnosis of
volvulus can have profound long-term outcomes.