Pediatric emergency medicine trisk 638

weeks. Infants will present with progressive, projectile nonbilious emesis, and in
advanced cases, severe dehydration, electrolyte imbalances, and hypoglycemia.
Some infants may tolerate clear fluids, such as Pedialyte, but will vomit with
milk. Early exposure to macrolides has been associated with the development of
hypertrophic pyloric stenosis. Diagnosis can be confirmed by clinical
examination of a palpable mass in the epigastrium that is roughly the size and
shape of an olive. In the absence of a palpable mass, diagnosis can be made by
US, which would reveal increased diameter, thickness and length of the pylorus.
Definitive treatment remains surgical pyloromyotomy. As hypertrophic pyloric
stenosis is not a surgical emergency, the infant should be fully stabilized and
resuscitated with adequate fluids and any electrolyte disturbances corrected prior
to surgical repair (see Chapter 12 Abdominal Distention ). Preterm infants with
hypertrophic pyloric stenosis are not affected by corrected gestational age at
presentation, however are more likely to have a higher complication rate and
longer length of stay compared to term infants.
Meconium Syndromes
Meconium syndromes can result in intestinal obstruction due to thick, inspissated
meconium. Meconium ileus occurs in up to 20% of infants with cystic fibrosis
and is often the first manifestation of the disease. Abnormal mucosal cell
secretion in this population results in thickened meconium throughout the small
intestines and into the colon. It often presents with failure to pass meconium
within 48 hours, progressive abdominal distention, eventual feeding intolerance,
and clinical signs of bowel obstruction, including bilious vomiting. Abdominal
radiography may reveal distended bowel loops typical of obstruction, as well as a
granular appearance of the retained meconium within the bowel. Complications
of meconium ileus include volvulus, necrosis, or perforation—which can also
occur prenatally. Contrast enema will often demonstrate microcolon, but can also
be therapeutic if the contrast can reflux into the ileum and the retained meconium
is washed out. The infant must be well hydrated to compensate for fluid shifts
associated with the hyperosmolar enema, and care must be taken to avoid
perforation or enterocolitis. If the enema is incomplete or the patient has

complicated meconium ileus, management typically requires surgical intervention
to irrigate the bowel and evacuate the meconium, as well as address any
associated atresia, necrosis, perforation, or volvulus. Meconium peritonitis can
occur from in utero bowel necrosis and perforation with subsequent leak of
meconium into the peritoneal cavity. Meconium in the peritoneum is often
accompanied by inflammatory changes that may result in peritoneal calcifications


and abdominal scarring. Infants with meconium peritonitis and signs of intestinal
obstruction often require exploratory laparotomy.
Meconium plug syndrome is thought to occur because of colonic hypomotility,
and is commonly seen in preterm infants and infants of diabetic mothers. Similar
to meconium ileus, neonates typically present with failure to pass meconium
within the first few days of life and progressive abdominal distention. Contrast
enema is often diagnostic and therapeutic, with much higher success rate of fully
evacuating the meconium than with meconium ileus. The need for surgical
evacuation of the meconium is uncommon; however, meconium plug syndrome
may be associated with Hirschsprung disease and cystic fibrosis, so patients
should be evaluated for both.
Hirschsprung Disease
Hirschsprung disease results from an aganglionic segment of the colon that
results in a distal intestinal obstruction. Up to 90% of infants present in the
neonatal period with abdominal distention, emesis, and failure to pass meconium.
The abdomen is often soft, and a digital rectal examination may result in
explosive stool. Contrast enema can be diagnostic in up to 80% of cases when a
transition zone is identified. Definitive diagnosis is achieved by identification of
complete aganglionosis on a biopsied specimen. Eight percent of cases will have
total colonic Hirschsprung. Hirschsprung-associated enterocolitis occurs in up to
10% of cases but can be life threatening if unrecognized. Treatment for
enterocolitis requires emergent decompression of the rectum and broad-spectrum

antibiotics. Definitive treatment of Hirschsprung disease requires surgical
resection of the aganglionic segment.
Anorectal Malformations
Anorectal malformations leading to intestinal obstructions include the
imperforate anus. Most patients have associated fistulas that result in some
meconium passage that can delay diagnosis. In males, the fistulas can occur
between the rectum and urinary tract, and in females between the rectum and
perineum, vestibule, or bladder. Clinicians should examine the perineum closely
and look for associated malformations of the sacrum, spine, spinal cord, and
genitourinary tract. Treatment requires surgical correction of the malformation,
which may include primary repair or colostomy, depending on the presence of
associated anomalies.
Adhesions


Infants with a history of bowel surgery can develop adhesions that present with
intestinal obstruction. This could include patients with a history of congenital
diaphragmatic hernia, omphalocele, gastroschisis, intestinal atresia, or meconium
syndrome, as well as patients with a history of NEC.

Necrotizing Enterocolitis
CLINICAL PEARLS AND PITFALLS
Although necrotizing enterocolitis (NEC) is most common in the
premature infant, up to 10% of cases occur in the term infant.
Term infants with NEC often have specific risk factors that increase the
risk of intestinal asphyxia or altered gut perfusion.
Infants with a history of NEC can present with small bowel obstruction
months after resolution of NEC.
Current Evidence
NEC is a gastrointestinal emergency where progressive mucosal injury and

inflammation result in bowel necrosis. While the incidence of NEC is inversely
proportional to gestational age, up to 10% of cases occur in the term neonate. Up
to a third of cases of NEC result in death, and postsurgical survivors have an
increased risk of developing short-bowel syndrome. While the exact etiology
remains unknown, elements of ischemic injury, intestinal hypoxia, coagulation
necrosis, acute or chronic inflammation, and bacterial overgrowth of the GI tract
are all likely contributors. Term infants with a history of intrauterine growth
restriction or SGA, congenital heart disease, meningomyelocele, and
gastroschisis have increased risk of developing NEC. Similarly, term and preterm
infants with a history of polycythemia, exchange transfusion, umbilical
catheterization or asphyxia, are also at increased risk of developing NEC.
Goals of Treatment
The primary goal of treatment is early recognition of NEC so that supportive
therapy can ameliorate bowel necrosis. Treatment includes fluid resuscitation and
blood pressure support, bowel rest, and broad-spectrum antibiotics that cover
enteric bacteria. Acidosis, anemia, and thrombocytopenia should be corrected.
Evidence of intestinal perforation (up to 50% of cases) requires surgical
intervention with either a drain procedure or laparotomy. Patients with necrotic
bowel may present without perforation but worsening abdominal discoloration


and distention and persistent thrombocytopenia and acidosis. Exploratory
laparotomy is often indicated in this group to identify and remove the necrotic
segment.
Clinical Considerations
Clinical Recognition. The signs associated with NEC are often nonspecific and
can include hematochezia, emesis or feeding intolerance, abdominal distention,
lethargy, and apnea and bradycardia. In advanced disease, there is also
tachycardia, abdominal tenderness with discoloration, respiratory failure, and
shock. Laboratory analysis may reveal neutropenia, thrombocytopenia, metabolic

acidosis, and/or hyponatremia.
Triage Considerations. Neonates with suspected NEC should be triaged urgently
as the disease can progress rapidly to respiratory failure and shock.
Clinical Assessment. The most common presenting sign in the neonate is emesis.
The examination may reveal a distended abdomen; however signs of peritonitis
or shock are often late findings and may not be present. The diagnosis is made by
the identification of pneumatosis intestinalis, portal venous gas, or
pneumoperitoneum on abdominal radiograph ( Fig. 96.40 ). In mild cases, plain
radiographs may reveal signs of ileus but no evidence of pneumatosis; in these
cases, portal venous gas may be appreciated by US.
Management. There is no specific treatment for NEC other than supportive
therapy. Bowel rest is indicated, with gastric decompression. Fluid resuscitation
is often required, and in advanced disease, may also require blood pressure
support. Due to the mucosal injury and bacterial translocation of intestinal flora,
broad-spectrum antibiotics are indicated. Blood cultures should be drawn prior to
the initiation of antibiotics, and will be positive in approximately one-third of
cases. Two-view radiographs of the abdomen are indicated to detect pneumatosis
and/or pneumoperitoneum. Laboratory evaluation should include blood cultures,
complete blood count, basic metabolic profile, blood gas, and, in severe cases
accompanied by disseminated intravascular coagulation, coagulation studies.
Surgical intervention is warranted if there is evidence of intestinal perforation or
if there is worsening of clinical symptoms that suggest a necrotic segment. Bowel
necrosis is often accompanied by persistent thrombocytopenia and acidosis, with
systemic signs of respiratory failure and shock.