David I. Magilner
The causes of abdominal pain and gastrointestinal (GI) bleeding vary by age and are listed in Tables 76-1 and 76–2.
TABLE 76-1 Classification of Abdominal Pain by Age Group
TABLE 76-2 Age-Based Causes of Upper and Lower GI Bleeding
Abdominal pain can be caused by infection, inflammation, or obstruction of any of the GI or genitourinary (GU) organs. In addition, abdominal pain may be caused by a systemic illness, pregnancy, or its complications, or may be referred from an extra-abdominal site. See Chapter 38 for further discussion on the pathophysiology of abdominal pain.
GI bleeding can occur anywhere along the GI tract from the esophagus to the anus, or be swallowed from bleeding in the nose or mouth. Bleeding can be caused by mucosal injury from a localized process; by infection, food allergy, and ingestion of a toxin or foreign body; or by a condition that increases bleeding.
Pain: The quality, timing, location, and exacerbating factors of abdominal pain provide clues to diagnosis. The two main types of abdominal pain in emergent conditions are peritoneal and obstructive: peritoneal pain is exacerbation by motion, while obstructive pain is spasmodic, and usually causes restlessness.
Associated symptoms and exposure to ill close contacts may also provide clues to etiology. In children less than 2 years of age, abdominal pain may be nonspecific and manifest as fussiness or lethargy.
Bleeding: The volume and quality of bleeding, along with associated symptoms, helps identify the cause of GI bleeding.
Associated symptoms: In addition to pain and bleeding, patients with abdominal emergencies may have associated symptoms such as vomiting, diarrhea, constipation, fever, anorexia, or jaundice. Jaundice often indicates a serious condition. Bilious vomiting in the first year of life should always be considered a symptom of obstruction and a true surgical emergency.
Physical examination in the child with abdominal pain or GI bleeding must first identify the need for resuscitation by assessment of general appearance, vital signs, perfusion, mental status, and hydration status. Abdominal examination may reveal distension, masses, localized tenderness, or peritoneal signs such as guarding, rebound pain, and “shake” or “hop” tenderness. A rectal examination should be considered to test for blood.
Non-GI sources of abdominal pain, such as pharyngitis, pneumonia, and testicular torsion, should be sought and all patients examined for hernias. A pelvic examination should be considered in any female patient who is post-menarchal.
DIAGNOSIS AND DIFFERENTIAL
The specific diagnosis for abdominal emergencies can be narrowed by the patient’s age. Tables 76-1 and 76–2 list the age-based causes of abdominal pain and GI bleeding. The most important diagnoses and some of their key characteristics are discussed below.
Intussusception may occur at any age, but has a peak incidence of 3 months to 2 years. Key features may include colicky abdominal pain, vomiting, “currant jelly” stool, and listlessness between episodes of pain. A sausage-like mass may be felt in the right abdomen. Diagnosis can be suggested by abdominal radiographs, but ultrasound has a higher sensitivity and specificity, and air contrast enema provides definitive diagnosis and potential treatment. Ultrasound may show a classic “target sign” (Fig. 76-1). A surgeon should be consulted prior to enema in case of failure or perforation.
Malrotation and volvulus can also occur at any age, but the vast majority of patients present in the first year of life. Volvulus occurs when a malrotated gut twists, compromising perfusion and leading to bowel ischemia and necrosis. Key features may include sudden abdominal pain and distension, bilious emesis, irritability, and eventually peritonitis and shock. If the diagnosis is in question and the patient is stable, radiographs including plain films and an upper GI series may aid in diagnosis, but surgical consultation should never be delayed.
Incarcerated hernia can present at any time in life, and the diagnosis is made by the presence of an inguinal or scrotal mass. Additional symptoms may include poor feeding, irritability, or vomiting. See Chapter 45 for further discussion on hernias.
Appendicitis can occur at any age, but peak incidence is between 9 and 12 years. Patients under 5 years of age are at high risk of perforation because of atypical symptoms and delayed diagnosis. Key features include periumbilical pain that migrates to the right lower abdomen, anorexia, nausea, vomiting, and fever; diarrhea may occur. However, this constellation of symptoms is present in <50% of cases. Studies that may aid in the diagnosis include the white blood cell (WBC) count, which if normal or low makes appendicitis less likely, and ultrasound (US) or CT imaging. Both ultrasound and CT are highly sensitive and specific (around 90%), but US is operator dependent. If a CT is performed, it should be done with IV (and possibly PO or rectal) contrast.
Necrotizing enterocolitis (NEC) is more common in low-birth-weight and premature infants, but 10% to 15% of cases occur in term infants. Most cases present in the first week of life. Key features include poor feeding, lethargy, and abdominal distension, and peritonitis and shock can result from intestinal perforation. Stool may test positive for occult blood, and plain films of the abdomen show air bubbles in the wall of the bowel (pneumatosis coli), which is diagnostic of NEC, and possibly portal venous or free air.
Nonspecific (or functional) abdominal pain is a diagnosis of exclusion. It is the most common diagnosis in children who present to the emergency department with abdominal pain, and may be considered a provisional diagnosis if the history, physical examination, and laboratory and radio-logic studies (if needed) are normal. Most children have vague, periumbilical, or lower abdominal pain, which can be associated with nausea. All children discharged with this diagnosis should follow up with a physician within 24 hours if pain is not resolved.
Constipation is a clinical diagnosis, defined by either infrequent and hard stools or pain with defecation. Most cases are functional or related to diet, but constipation may be indicative of a more serious condition such as Hirschsprung’s disease or cystic fibrosis. Physical examination should include examination of the spine for signs of dys-raphism (dimples, clefts, tufts of hair) and possibly rectal examination to assess sphincter tone and the presence or absence of stool in the vault.
Henoch–Schönlein purpura (HSP), also known as anaphylactoid purpura, is a vasculitis that affects vessels in the skin, intestine, kidneys, and joints. The rash is purpuric and palpable, and typically presents on the lower extremities and buttocks first. Arthritis and arthralgia are migratory and usually involve the ankles and knees. Renal involvement may manifest as hematuria or hypertension (see Chapter 28). Abdominal pain is present in 60% to 80% of cases, and is usually diffuse and colicky. It may be accompanied by vomiting and/or GI bleeding. In most cases, the pain is a direct result of intestinal vasculitis, but in about 5% of patients an intussusception will develop secondary to the vasculitis.
Pyloric stenosis presents with projectile non-bilious vomiting that occurs after feeds, and may present anytime from 2 to 12 weeks of life. The diagnosis may be suggested by palpation of an “olive” in the left upper abdomen, confirmed by ultrasound. Laboratory evaluation may show a hypokalemic, hypochloremic metabolic alkalosis, but this is a late finding.
Meckel’s diverticulum most commonly causes painless hematochezia, but may act as a lead point for volvulus or intussusception.
Other causes of GI bleeding are listed in Table 76-2. In most cases, the responsibility of the emergency room caregiver is to ensure that the patient is stable by assessing vital signs, hydration status, and presence or absence of anemia. Most entities will require either emergent or non-emergent referral to a pediatric gas-troenterologist or surgeon for definitive diagnosis (eg, endoscopy or biopsy) and management.
Systemic infectious and noninfectious diseases that may cause abdominal pain are discussed elsewhere, but include streptococcal pharyngitis, pneumonia, diabetic ketocidosis, urinary tract infection, and sickle-cell disease.
Other important causes of abdominal pain discussed elsewhere include colic (Chapter 69), gastroenteritis (Chapter 75), cholesystitis (Chapter 44), pancreatitis (Chapter 44), renal stones (Chapter 58), and inflammatory bowel disease (Chapter 39).
FIG. 76-1. A and B. US image of intussusception showing the classic target appearance of bowel within bowel. (Reprinted with permission from Reardon RF, Joing SA: Cardiac, in Ma OJ, Mateer JR, Blaivas M (eds): Emergency Ultrasound, 2nd ed. © 2008, The McGraw-Hill Companies, All rights reserved, New York. Figure 9–15A&B.)
EMERGENCY DEPARTMENT CARE AND DISPOSITION
In all cases the first responsibility is to assess whether the patient is stable. This includes an assessment of general appearance, vital signs, perfusion, mental status, and hydration. Standard resuscitation efforts should begin immediately when necessary.
Treat shock from abdominal emergencies with aggressive isotonic crystalloid boluses: 20 mL/kg of normal saline or lactated Ringer’s solution should be administered and repeated until clinical improvement is noted.
Consider administration of blood products (eg, packed red blood cells, fresh frozen plasma—see Chapter 87) for patients with life-threatening and ongoing GI bleeding.
Treat significant pain with parenteral narcotics such as morphine 0.1 milligram/kg IV; administration of narcotics does not alter the reliability of the physical examination to detect peritoneal signs and should not be withheld.
Obtain laboratory and radiographic studies as directed by the presentation and suspected etiology.
Obtain surgical or GI consultation as indicated, and consider rapid transfer to a pediatric facility after initial resuscitation for patients with a suspected surgical process.
For further reading in Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 7th ed., see Chapter 124, “Acute Abdominal Pain in Children,” by Anupam B. Kharbanda and Rasha D. Sawaya, and Chapter 125, “Gastrointestinal Bleeding in Children,” by Robert W. Schafermeyer and Emily MacNeill.