Strange and Schafermeyer's Pediatric Emergency Medicine, Fourth Edition (Strange, Pediatric Emergency Medicine), 4th Ed.

CHAPTER 45. Late-Presenting Neonatal Surgical Emergencies

Curt Stankovic

Prashant Mahajan

HIGH-YIELD FACTS

• Necrotizing enterocolitis (NEC) can occur in full-term newborns with existing medical conditions.

• Vomiting in a newborn should be considered bilious if it shows a color other than white.

• A newborn with vomiting, especially bilious emesis, should be evaluated for malrotation with midgut volvulus.

• Any patient who has suspicion of malrotation with midgut volvulus should undergo an emergent upper GI contrast study with small bowel follow-through.

• Patients with Hirschsprung’s disease can present with chronic, progressive constipation and failure to thrive.

Although an uncommon occurrence, the presentation of neonatal surgical emergencies after discharge from the newborn nursery are often life-threatening and require prompt evaluation, stabilization, and emergent referral to a pediatric surgeon. Three such conditions are necrotizing enterocolitis (NEC), malrotation with midgut volvulus, and Hirschsprung’s disease.

NECROTIZING ENTEROCOLITIS

Necrotizing enterocolitis (NEC) is the most common gastrointestinal emergency and the most common cause of intestinal perforation in the newborn period.1 It is usually a disease of preterm infants with low birth weight,2 although nearly 5% to 15% occur in term infants.24 Term infants are more likely than their preterm counterparts to have predisposing risk factors25 (Table 45-1). The vast majority of term infants with NEC have some underlying illness.5Over 90% of full-term infants with NEC present within the first 4 days of life and the disease tends to advance more rapidly than in preterm infants.5 Mortality rates of infants with NEC have been reported between 12% and 30%.2,4The diagnosis of NEC is based upon a three-stage classification system.6,7 Stage I is suspected disease; Stage II is definite disease; and Stage III is advanced disease (Table 45-2).

TABLE 45-1

Risk Factors for Necrotizing Enterocolitis in Full-Term Infants

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TABLE 45-2

Classification System for Necrotizing Enterocolitis

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The development of NEC is multifactorial. Enteral intake in the presence of reduced blood flow and bacteria leads to mucosal inflammation and ulceration.8 A compromise in the intestinal mucosal barrier allows bacteria to spread, leading to intestinal perforation, necrosis, and the development of sepsis.9

SIGNS AND SYMPTOMS

A high index of suspicion should be maintained because clinical findings of early-stage disease may be nonspecific. Infants present with feeding intolerance, decreased activity, vomiting, and diarrhea.10Abdominal examination findings in mild or early disease may be limited to abdominal distention, which is the most common presenting sign. 11 Typically, it rapidly progresses to peritonitis, with bilious emesis, abdominal tenderness, and grossly bloody or guaiac positive stool.12 Erythema or ecchymosis of the abdominal wall occur late in the course of disease. Although some patients experience spontaneous improvement and resolution, many develop signs of DIC, shock, respiratory failure, and eventually death.11

DIAGNOSTIC EVALUATION

The diagnosis of NEC can be confirmed by abdominal radiographs if gas within the bowel wall (pneumatosis intestinalis) or portal venous gas is seen (Fig. 45-1). Finding free air in the abdominal cavity indicates that a perforation has occurred. The presence of a sentinel loop indicates necrotic bowel. Ultrasound can be helpful as an ancillary investigation assisting in the management after the admission to a critical care unit.

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FIGURE 45-1. A 2-week-old infant with Down syndrome presented to the ED with rectal bleeding. The radiograph demonstrates diffuse linear pneumatosis indicative of necrotizing enterocolitis.

Blood tests should be used to identify complications caused by advanced disease such as electrolyte abnormalities, consumptive coagulopathy, or sepsis. In these infants, the WBC may be low due sepsis, and thrombocytopenia signals the presence of DIC. Blood glucose instability may occur and blood-gas abnormalities are found with sepsis and shock. Blood cultures are positive in approximately 30% of patients with NEC.3

MANAGEMENT

The initial ED evaluation focuses on identifying patients with intestinal perforation, peritonitis, shock, or sepsis. Aggressive and prompt management of these complications are essential and may be life-saving. The management of shock and DIC is described in Chapters 19 and 105, respectively. Infants with suspected NEC should be treated with a broad-spectrum antibiotic regimen. Concurrent with stabilization of life-threatening conditions, emergent admission to a critical care unit and referral to a pediatric surgeon is indicated. Supportive care includes a nasogastric tube for gastric decompression, NPO status, and ongoing intravenous fluid and electrolyte therapy.

MALROTATION WITH MIDGUT VOLVULUS

Malrotation is a failure of completion of the embryonic rotation of the gastrointestinal tract. It may result in the suspension of a portion of bowel from a narrow pedicle. Patients with this narrow supporting foundation are at risk for volvulus, which is the twisting of the bowel and its vascular supply, resulting in obstruction and eventually ischemia.13

Malrotation with midgut volvulus typically affects the previously healthy neonate with 50% of all patients presenting in the first week of life and 75% within the first month.14 Malrotation has been estimated at 1 in 6000 live births and is twice as common in boys.15 The median age at diagnosis is 2 months, while the mean age is 3 years.16 Autopsy evidence suggests that malrotation is present in up to 1% of the population.17

SIGNS AND SYMPTOMS

Symptoms typically present acutely and involve bilious vomiting and signs of an acute abdomen. Bilious emesis in a newborn is a surgical emergency because it is the most common presenting complaint of patients with volvulus.16,18 Vomitus of any color other than white should be considered bilious until proven otherwise in the newborn age group. Some patients may present with intense, episodic crying or anorexia.16,19 As the disease evolves, vomiting becomes repetitious, abdominal distention becomes apparent, and irritability progresses to metabolic acidosis and shock. Late examination findings include hematemesis, abdominal ecchymosis, and melena from bowel necrosis.

Many infants do not present in this classic manner. Malrotation with midgut volvulus can go undiagnosed for months or even years due to vague symptoms which include feeding intolerance, episodic abdominal pain or distention, constipation, and failure to thrive.20 Infants over 2 months of age often present with nonspecific complaints such as feeding intolerance, transient and chronic abdominal pain, intermittent vomiting, chronic diarrhea, and malabsorption.14,16 These symptoms are thought to be due to an intermittent or partial twisting resulting in lymphatic and venous obstruction. Nonbilious vomiting is the second most common complaint and is more common outside of the neonatal age group.18

DIAGNOSTIC EVALUATION

Radiography is the key diagnostic investigation for suspected midgut volvulus. Infants with bilious vomiting or with suspicion of volvulus should undergo an emergency upper gastrointestinal contrast study with small bowel follow through (UGI) (Fig 45-2). The radiologist performing the study should provide the clinician with immediate feedback.

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FIGURE 45-2. A previously well 2-week-old infant presented to the ED with bilious emesis. The UGI study showed delayed progression of contrast from the proximal duodenum without visualization of the duodenojejunal junction. This is indicative of malrotation with midgut volvulus.

Abdominal radiographs are less reliable and they should be used to identify free intraperitoneal air or a distal bowel obstruction21 (Fig. 45-2).

MANAGEMENT

Patients with a clinical picture that is suspicious for volvulus should be managed aggressively with intravenous fluid resuscitation, analgesics, nasogastric decompression, and broad-spectrum antibiotics. The management of shock and sepsis is described in Chapters 19 and 105, respectively. Blood tests listed in the previous section on NEC should be obtained. Early surgical consultation even prior to the definitive diagnosis is recommended and may hasten time to laparotomy. Concurrent arrangements for admission to a critical care unit should be undertaken. Patients who present with chronic symptoms should have a more comprehensive laboratory workup including electrolytes, liver function tests, and an albumin level because these patients commonly have protein–calorie malnutrition.20

The risk of catastrophic consequences exists, regardless of age. Mesenteric vascular compromise caused by the twisting midgut rapidly leads to peritonitis, sepsis, and death.22 Aggressive management, prompt imaging, and surgical consultation are imperative for optimal outcome.

HIRSCHSPRUNG’S DISEASE

Hirschsprung’s disease is caused by the congenital absence of parasympathetic ganglion cells in the colon. As a result, the segment of agangliotic colon is unable to relax, resulting in functional obstruction.23The agangliotic bowel begins at the rectal sphincter and extends proximally.24 Short-segment disease is more common than long-segment disease and does not extend beyond the upper sigmoid colon. Long-segment disease involves various lengths of intestine and occasionally involves the small bowel or entire bowel.25 Ultra-short segment Hirschsprung’s disease, the least common type, is limited to the anal sphincter and has been defined as an agangliotic segment less than 4 cm in length.26

It occurs in 1 of every 5000 live births, is more common in boys, and in Asian or Hispanic ethnicities.27 Hirschsprung’s disease has been associated with other abnormalities in 29% of all patients, most commonly trisomy 21 (Table 45-327). The major cause of morbidity and mortality is enterocolitis. Enterocolitis occurs preoperatively in 10% to 30% of patients and is more common if the diagnosis is delayed.27,28

TABLE 45-3

Hirschsprung’s Disease Associated Conditions

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SIGNS AND SYMPTOMS

Symptoms are related to the length of affected colon. Patients typically have infrequent, explosive episodes of diarrhea due to functional abdominal obstruction. Symptoms range from chronic progressive constipation to obstruction. About 70% to 90% of newborns with Hirschsprung’s disease fail to pass meconium in the first 24 hours of life.27,28 If not diagnosed in the neonatal period, most will present with poor feeding, difficulty having bowel movements, and progressive abdominal distention.28 Those who present with abdominal obstruction or enterocolitis are more likely to present in the first week of life.27Older children may have episodes of recurrent fecal impaction, failure to thrive, hypoalbuminemia, malnutrition,29 or infrequent, explosive episodes of diarrhea due to functional abdominal obstruction. Hirschsprung’s disease must be differentiated from functional constipation in older children. The key physical examination finding is a tight anal sphincter with an empty rectum and upon termination of a rectal exam there is an explosive discharge of stool or flatus.30 Patients may also have abdominal distention and palpable fecal material on abdominal examination. Children with Hirschsprung’s enterocolitis initially present with abdominal distention, foul-smelling watery stool, lethargy, and poor feeding. This progresses to fever, dehydration, emesis, and hematochezia. As the disease evolves, intestinal epithelial inflammation progresses to erosion and eventual perforation27 (Fig. 45-3).

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FIGURE 45-3. An 18-day-old infant presented with abdominal distention and diminished stool output with one episode of nonbilious vomiting. The radiograph shows a paucity of air in the rectum and markedly distended large and small bowel suggestive of a distal obstruction. Diagnosis of Hirschsprung’s disease was confirmed with biopsy.

image DIAGNOSTIC EVALUATION AND MANAGEMENT

Children suspected of having Hirschsprung’s disease who are not acutely ill should be referred to a pediatric surgeon or gastroenterologist for assessment, investigation, and management. The key investigations are a contrast enema and a rectal biopsy.

Children with enterocolitis require inpatient management aimed at preventing and limiting disease progression. Those with apparent sepsis or shock require the approach described in the previous section on NEC.

Surgical correction of Hirschsprung’s disease provides near-normal gastrointestinal function for most children.31 However, some patients experience some long-term postoperative complications. Persistent constipation or fecal incontinence ranges from 2.5% to 13%.31 This may be a reason for emergency department presentation months after surgery.

REFERENCES

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image MALROTATION

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image HIRSCHSPRUNG’S DISEASE

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31. Marty TL, Seo T, Matlak ME, et al. Gastrointestinal function after surgical correction of Hirschsprung’s disease: Long-term follow-up in 135 patients. J Pediatr Surg. 1995;30:655–658.