Chapter 74. Pediatric Abdominal Emergencies

Pediatric abdominal pain is a common presenting complaint in the emergency department. The assessment of acute abdominal pain can be challenging given the preverbal state of young children, the varied number of diagnoses that present similarly, and increasing appreciation of risks associated with pediatric diagnostic imaging.

Clinical Features

Presenting signs and symptoms differ by age. The key gastrointestinal (GI) signs and symptoms include pain, vomiting, diarrhea, constipation, bleeding, jaundice, and masses. Pain in children younger than 2 years typically manifests as fussiness, irritability, lethargy, or grunting. Toddlers and school age children often localize pain poorly and point to their umbilicus. Pain may be peritoneal and exacerbated by motion, or obstructive, spasmodic, and associated with restlessness. Abdominal pain may originate from non-GI sources, and associated symptoms may help localize extra-abdominal causes such as cough with pneumonia, sore throat in streptococcal pharyngitis, and rash in Henoch-Schönlein purpura (HSP).

Vomiting and diarrhea are common in children. These symptoms may be the result of a benign process or indicate the presence of a life-threatening process. Bilious vomiting is almost always indicative of a serious process, especially in the neonate. GI bleeding can result from upper or lower sources. Upper GI bleeding in children presents with hematemesis, which is often frightening to caretakers, but rarely serious in an otherwise healthy infant or child. Lower GI bleeding presents with melena or hematochesia, and the distinction between painless and painful rectal bleeding can help differentiate likely etiologies (see GI Bleeding below). Jaundice can be an ominous sign, and all icteric infants should be fully evaluated for sepsis, congenital infections, hepatitis, anatomic problems, and enzyme deficiencies. Abdominal masses may be asymptomatic (eg, Wilms tumor) or associated with painless vomiting (eg, pyloric stenosis) or colicky abdominal pain (eg, intussusception).

Diagnosis and Differential

Obtain a thorough history from parent and child (if possible), including the quality and location of pain, chronology of events, feedings, bowel habits, fever, weight changes, and other systemic signs and symptoms. Begin the physical examination with an assessment of the child's overall appearance, vital signs, and hydration status. The patient should be disrobed, and thorough inspection with nontouch maneuvers should precede auscultation and palpation. Extraabdominal areas including the chest, pharynx, testes, scrotum, inguinal area, and neck should also be evaluated. Adolescent females with lower abdominal pain may require a bimanual exam. The likely etiologies of abdominal pain change with age. Table 74-1 classifies emergent and nonemergent conditions by age group.

Neonates and Young Infants (0 to 3 Months)

Life-threatening abdominal conditions in young infants include necrotizing enterocolitis, and malrotation with midgut volvulus. Other urgent conditions include pyloric stenosis, incarcerated hernias (see Chapter 46), testicular torsion, and nonaccidental trauma. Inconsolability, lethargy, and poor feeding may be the only indication of serious underlying disease. Bilious vomiting in an infant indicates intestinal obstruction and should be considered a surgical emergency until proven otherwise. Common non-life-threatening causes of abdominal pain in young infants include colic (see Chapter 67) and constipation. Fever requires thorough investigation for a source (see Chapter 66). Other causes of irritability in infants should be considered, including hair or thread tourniquets of the digits and genitalia, and corneal abrasions (see Chapter 67).

Helpful studies in this age group include abdominal radiographs to identify obstruction or free air, abdominal ultrasound to diagnose pyloric stenosis, testicular torsion, and hernias, and upper GI contrast studies to identify malrotation. Useful laboratory studies include serum electrolytes to identify abnormalities resulting from vomiting and dehydration and a CBC and coagulation panel to identify DIC in abdominal catastrophe with perforation.

Malrotation of the intestine can present with life-threatening volvulus. Symptoms include bilious vomiting, abdominal distention, and obstipation, or, occasionally, streaks of blood in the stool. The vast majority of cases presents within the first month of life. Patients are ill appearing and may present in compensated or decompensated shock. Distended loops of bowel overriding the liver on abdominal radiographs, and a “bird's beak” appearance on an upper GI series are suggestive of this diagnosis. Immediate surgical consultation and aggressive fluid resuscitation are critical to maximize outcomes.

Pyloric stenosis usually presents with progressive nonbilious, projectile vomiting occurring just after feeding. Infants with pyloric stenosis are often described by parents as ravenous. Pyloric stenosis occurs most commonly in the third or fourth week of life, is familial and more common in first-born males. A left upper quadrant pyloric mass, or “olive,” may be present, and peristaltic waves may be noted following a feeding trial in the ED. Ultrasound is the imaging modality of choice. Electrolytes may demonstrate a characteristic hypochloremic metabolic alkalosis, which must be corrected prior to definitive surgical care. While pyloric stenosis is not a surgical emergency, the resultant dehydration from persistent vomiting requires immediate medical treatment.

Older Infants and Toddlers (3 Months to 3 Years)

The differential diagnosis of acute abdominal pain in this age group includes intussusception, gastroenteritis (see Chapter 73), constipation, urinary tract disease (see Chapter 75), and nonaccidental trauma. Though less common in this age group, acute appendicitis and malrotation with midgut volvulus must be considered.

Imaging studies are guided by the differential diagnosis: radiographs can help rule out free air or obstruction, and confirm suspected constipation; ultrasound can help identify intussusception or appendicitis; and air-contrast enema is both diagnostic and potentially therapeutic for intussusception. A CBC and electrolytes may be helpful in evaluating complications of vomiting and diarrhea, and urinalysis will identify pyelonephritis as a potential cause of abdominal pain in this age group.

Intussusception occurs when one portion of the bowel telescopes into another, which can result in a partial or complete obstruction, bowel-wall edema, and eventually ischemia. The greatest incidence occurs between 6 to 18 months of age. The classic presentation of intermittent paroxysms of abdominal pain with pain-free intervals (or lethargy), vomiting (may be bilious) and “currant jelly stool” are not present in all patients. Stool guaiac testing may reveal occult blood. Providers must have a high index of suspicion for intussusception in patients presenting with nonspecific changes in mental status or who are ill appearing without any apparent etiology. In equivocal cases, ultrasound is a sensitive test with a high negative predictive value and may demonstrate the classic “target sign” (see Fig. 74-1). In more classic cases, air or barium enema can be both diagnostic and therapeutic. Radiologic reduction requires the presence of a pediatric surgeon for irreducible cases or perforation during the procedure.

Constipation, defined as infrequent, hard stools, is a common cause of abdominal pain in children and may be a sign of either a pathologic (eg, Hirschsprung disease, cystic fibrosis, spinal cord abnormality) or functional process. History is key to the diagnosis. For neonates, verify passage of meconium in the first 24 hours of life. A rectal examination is recommended to assess presence of stool, rectal tone, sensation, and size of the anal vault. A careful lower extremity neurologic examination should be completed to assess for neuromuscular causes. A single upright abdominal radiograph may be helpful to visualize fecal retention or impaction, and to help rule out the concern for obstruction. Treatment in the ED with suppositories or enemas may be necessary, and outpatient maintenance therapy is essential to prevent recurrence. Admission is indicated for patients with impaction associated with vomiting, dehydration, and failure of outpatient treatment.

Children (3 to 15 Years Old)

Acute abdominal pain in children 3 to 15 years old includes a range of diagnoses, including appendicitis (Chapter 43), constipation (see above), gastroenteritis (Chapter 73), urinary tract infection (Chapter 75), streptococcal pharyngitis (Chapter 68), pneumonia (Chapter 71), pancreatitis (Chapter 42) and functional abdominal pain. An unusual but important cause of abdominal pain in this age group is Henoch-Schönlein purpura (HSP), which is discussed further below. The presence of a parent is helpful in examining younger children. Older children may not readily offer important history surrounding embarrassing topics such as constipation and genital pain. Adolescents should be interviewed alone to provide confidentiality and facilitate discussion of potentially important information surrounding sexual activity, substance use, and other sensitive subjects.

Henoch-Schönlein purpura is an idiopathic vasculitis of children between 2 and 11 years of age. HSP classically presents with acute abdominal pain, lower extremity purpura, and arthritis. Routine laboratory testing is not needed for classic cases, but can help rule out other conditions. A urinalysis should be obtained to identify hematuria, with subsequent renal function tests when blood is present. Abdominal pain in HSP is caused by bowel wall edema and GI vasculitis. Microscopic and even gross GI bleeding is not uncommon, though rarely life threatening. HSP is a known risk factor for intussusception in older children and this must be considered in patients with significant abdominal pain. Treatment of HSP is primarily supportive: joint pain responds well to non-steroidal antiinflammatory medications; severe abdominal pain may improve with corticosteroids. Consultation and follow-up with a pediatric rheumatologist or nephrologist may be necessary for more severe symptoms or renal involvement with hypertension.

Upper GI (UGI) bleeding is distinguished from lower GI (LGI) bleeding anatomically at the Ligament of Treitz. The presentation of GI bleeding in children varies, and includes bright red blood in small strands or clots in emesis or stool, vomiting of gross blood (hematemesis), black tarry stools (melena), or profuse bright red blood per rectum. Occult bleeding may present with pallor, fatigue, or anemia.

The first step in management is to evaluate the need for acute resuscitation, and distinguish the bleed as UGI or LGI. Confirmation through gastric or fecal occult blood testing is useful to distinguish substances that grossly mimic blood. A thorough history and physical examination is important to determine the location, amount, and etiology of the bleed. Examination for extragastrointestinal sources is also important (eg, epistaxis as a cause of hematemesis). The differential diagnosis of upper and lower GI bleeding by age group is summarized in Table 74-2. In general, upper GI bleeding in children without underlying portal hypertension is rarely life threatening. While most causes of lower GI bleeding in children are also benign, potential emergent causes include vascular malformations, Meckel diverticula, hemolytic uremic syndrome, and intussusception. In cases of melena, evaluate for causes of upper abdominal bleeding, and HSP. In cases of bright red blood per rectum, evaluate for anal fissure, or hemorrhoids. For painless hematochezia, consider Meckel diverticulum, or arteriovenous malformation. For hematochezia in the setting of abdominal pain, the differential is larger including: HSP, hemolytic uremic syndrome, infections gastroenteritis, inflammatory bowel disease, milk protein allergy, intussusception and necrotizing enterocolitis.

Laboratory studies and imaging should be completed as dictated by other associated signs and symptoms. Mild bleeding can typically be managed by a consultant on an outpatient basis. Moderate and severe bleeding requires acute resuscitation with isotonic crystalloid and, potentially, blood products. While acute shock should be treated immediately, overexpansion of intravascular volume should be avoided, particularly for variceal bleeding or more chronic conditions. Consultation with a pediatric surgeon, gastroenterologist, or critical care physician may be necessary, depending on the etiology.