“Mommy, my tummy hurts!” is a complaint heard frequently from children. Abdominal pain plagues almost all children at some point in their lives. For some, the pain is an acute, limited experience of viral gastroenteritis; others experience recurrent or chronic pain, such as in Familial Mediterranean Fever or Henoch-Schönlein purpura. Most cases require nothing more than observation and reassurance, although some require extensive evaluations or surgical interventions. Regardless of etiology, the provider will face the challenge of determining the best course of action for each patient with abdominal pain.

All people perceive pain differently. The perception of pain varies among individuals and cultures. The perception of pain may even vary for the same individual from one day to the next. Though perceptions and responses to pain vary, however, the pain stimulus is the same. Abdominal pain is caused by stimulation of afferent fibers within cells in the dorsal root ganglia. Some fibers cross the midline and ascend to the medulla, midbrain, and thalamus. The pain is perceived in the post-central gyrus of the cerebral cortex.

Organs in the abdomen do not detect painful stimuli caused by cutting or burning; yet they are sensitive to distention, compression, and torsion. It is the peritoneal covering and the skin and muscles overlying the abdomen that detect painful stimuli as a sharp sensation. Inflammation and infarction also cause pain when they affect the peritoneum.

The peritoneum, of mesodermal origin, covers the organs within (visceral layer) and the inner surface (parietal layer) of the abdominal cavity. Autonomic nerves innervate the visceral layer, and the pain detected tends to be midline. Somatic nerves of spinal origin innervate the parietal layer, and the pain is perceived at its location (Martin & Rossi, 1997). Additionally, different types of nerve fibers, originating at T7-L2, innervate the two peritoneal layers. The visceral peritoneum contains C fibers, which are slow and give the sensation of dull, aching pain. A-λ fibers innervate the parietal peritoneum; these fibers are much quicker and cause the sensation of sharp, severe pain. Thus, in early appendicitis, abdominal pain first is dull and central due to visceral peritoneal inflammation. As the process progresses, the parietal peritoneum becomes inflamed. The pain localizes to the right lower quadrant and becomes sharper and more severe.

The etiologies of abdominal pains can be divided into acute, chronic, and acute on chronic. They also can be divided into surgical, medical, and idiopathic. They may further be subdivided into age groupings, such as infant, toddler, and adolescent (Table 38-1).

Gastroenterological complaints are found in 5.4% to 13% of all children ages 17 years and younger [Centers for Disease Control and Prevention, 1994]. Abdominal pain may be acute, chronic, or recurrent. Recurrent abdominal pain is defined as three or more episodes of abdominal pain over a 3-month period (Seller, 1996). Patients with recurrent abdominal pain, however, may present with a new episode as “acute abdominal pain”.

Acute abdominal pain usually is defined as abdominal pain lasting less than 3 days. It accounts for approximately 5% of all unscheduled visits to primary care providers, urgent care centers, and emergency rooms (Scholer, Pituch, Orr, & Dittus, 1996). Fever, vomiting, anorexia, cough, and sore throat often accompany it. Most often, a “self-limiting” or medical condition such as “abdominal pain of uncertain etiology,” gastroenteritis, or constipation causes acute abdominal pain (Mason, 1996).

In most cases, medical treatment, supportive therapy, appropriate antibiotics, and observation are sufficient. In 1% to 2% of cases, however, surgical intervention is necessary (Scholer, Pituch, Orr, & Dittus, 1996).

Appendicitis is the most common reason that older children with abdominal pain require surgical intervention (74%). In 50% to 60% of cases of children admitted for possible appendicitis, however, observation and further evaluation preclude the need for surgical intervention. When surgery is performed, 10% of cases reveal no pathology (Holland & Gollow, 1996). In children younger than age 4 years, diagnosing appendicitis is often more difficult. In children younger than age 5 years, incarcerated hernias and intussuception are the most common reasons for abdominal pain requiring surgical intervention.

As with all diseases, the history and the physical exam are the guides to establishing a clinical diagnosis. Common questions to answer are the “PQRSTs” of pain:

P—place of pain. Where is it? Can the child point to it with one finger? Surgical etiologies tend to be more localized.

Q—quality of pain. Is it sharp? dull? aching? burning? colicky? crampy?

R—radiation of the pain. Does the pain stay in one place or go to the back? to the chest? Has the pain itself migrated?

S—symptoms associated with the pain. Is there vomiting? fever? anorexia? diarrhea? sore throat? The provider must explore a sexual history in all patients (including abuse as well as consensual activities).

T—timing of the pain. When did it start? How long does it last? How often does it occur? Has it happened before?

—things that make the pain better or worse. Does position, bowel movement, or medication affect the pain?

The provider must do the physical exam carefully and kindly, remembering that the patient is in pain. Since the abdomen is hurting, it is often best to examine it last. A thorough exam, starting with vital signs and including respiratory rate, pulse, blood pressure, and temperature, is essential. Tachypnea is seen with pneumonia. Tachycardia and hypotension occur with sepsis, peritonitis, or profound anemia and hemorrhage. Observing the skin, looking for any rash or pallor, may help identify hemolytic or sickle cell anemia, as well as purpura. A cardiac evaluation may reveal a murmur secondary to anemia (from GI bleeding, sickle cell
disease, or other etiologies). Auscultation of the lungs may uncover lower lobe pneumonia.

The abdominal exam should begin with observation. The provider should approach the child gently. This is best done after first talking with the child and parent and establishing trust. The clinician should note the child’s facial expression, so he or she can compare it to a “grimace” while palpating the abdomen. A grimace is often a more sensitive tool than any verbal acknowledgment of pain (Wagner, McKinney, & Carpenter, 1996). The clinician should observe the patient’s position, noting if he or she is bent over or writhing with pain. The provider should note the skin over the abdomen. Discoloration of the flank (Gray-Turner sign) or periumbilical discoloration (Cullen sign) occurs with hemorrhagic pancreatitis.

Auscultation should precede palpation; palpation that elicits pain may cause a paralytic ileus, and the provider may not be able to hear bowel sounds. The absence of bowel sounds indicates ileus and thus requires hospital admission. High pitched/hyperperistaltic sounds suggest mechanical obstruction. Prior to auscultation, allowing the child to touch the stethoscope and even place it on his or her abdomen eases anxiety.

The provider should perform palpation gingerly, starting with an area that is not painful and moving clockwise toward the painful area. The patient should lie supine, with knees slightly flexed. Engaging the child in conversation helps to distract him or her from the pain and the exam. Superficial palpation should precede deep palpation.

The clinician should note signs of guarding, rebound, and any masses. The cough test (in which voluntary coughing elicits abdominal pain) has a sensitivity of 78% and a specificity of 79% for diagnosing peritonitis (Bennett, Tambeur, & Campbell, 1994) and is more sensitive than the manual test for rebound. The “heel drop jarring test,” in which the patient drops onto his or her heels after standing on the toes for 15 seconds, or to have the patient hop on one leg several times also may be used to diagnose peritonitis.

A rectal exam is part of the routine exam when the provider suspects a diagnosis of an acute abdomen. It may not aid in diagnosis, however, and is not always necessary (Mason, 1996). Though generally the rectal exam is uncomfortable, reproducing the pain on rectal exam when pressing on the appendix increases the suspicion of appendicitis. Stool guaiac testing reveals occult blood. Sexually active females should have a gynecological (speculum and bimanual) exam.

After performing the history and physical exam, the provider should begin a diagnosis-specific approach. He or she may treat obvious etiologies for abdominal pain, such as simple gastroenteritis, irritable bowel syndrome (IBS), upper respiratory illness, and otitis media without further testing. When testing is appropriate, the clinician should perform tests to confirm or exclude specific diagnoses.

Treatment of acute abdominal pain depends on its etiology. First and foremost is the necessity to identify the causes and development of the pain. Even if a diagnosis is not possible, the provider must determine a disposition. Is the patient stable enough to be sent home, or does he or she require hospitalization? If a child is found to have signs of an acute abdomen, then hospitalization, observation, and consultation with a surgeon is needed. If symptoms seem benign and recurrent (as suggestive of irritable bowel), then counseling and reassurance are appropriate. In all cases, the clinician must address severity of the pain, employ appropriate analgesics (when warranted), and correct and maintain hydration status. Specific treatments are described below for each disease.

Appendicitis is the most common diagnosis considered when children younger than age 14 years present with abdominal pain to the emergency room or provider’s office (Simpson & Smith, 1996). Only a small percentage of patients, however, actually have appendicitis. Because of the high morbidity and mortality that can result from a perforated appendix, it is a diagnosis that must not be missed. The incidence of pediatric patients with perforated appendices at the time of diagnosis ranges from 30% to 65%. The diagnosis becomes even more difficult when the child is younger (Mason, 1996).

Up to 22% of the U.S. adult population has irritable bowel syndrome (IBS). Most of these individuals are diagnosed in young adulthood and adolescence (Lynn & Friedman, 1995). These patients comprise up to 25% of referrals to gastroenterologists. The condition is twice as common in females than in males (except in India and Sri Lanka, where it is more common in males). Ten to 15% of school-aged children have recurrent abdominal pain, 52% of whom were diagnosed with IBS (Hyams, 1995).

Peptic ulcer disease most frequently occurs in adults. It may afflict adolescents and children but is rare in toddlers. The bacteria Helicobacter pylori usually is found. Research shows it to be more common in patients from lower socioeconomic status, but some studies have challenged this finding (Macarthur, Saunders, & Feldman, 1995). Symptoms range from chronic abdominal pain to GI bleeding. Treatment consists of eradication of H. pylori with proton pump inhibitors and antibiotics. Short-term continuation of acid reduction (with proton pump inhibitors, H₂ blockers or antacids) is usually necessary. If the diagnosis is questionable, treatment seems suboptimal, or complications are suspected, a gastroesophagoduodenoscopy (EGD) or an upper GI series is warranted.

Pancreatitis may occur throughout childhood and most commonly results from a mumps infection. When secondary to other etiologies, pancreatitis in childhood is rare and often associated with trauma, medications (eg, thiazides, steroids, estrogens), diseases (eg, diabetes mellitus, cystic fibrosis, hemolytic uremic syndrome, or liver diseases), or familial causes.

The pain is usually epigastric, and boring, drilling straight to the back. Nausea and vomiting are often present. Laboratory evaluation must include a CBC, amylase, lipase, serum glucose, BUN, electrolytes (SMA 6), liver function tests, and calcium. Additionally, an arterial blood gas is warranted. Treatment includes appropriate anal-gesia and sufficient hydration. Hospitalization, with intravenous hydration and bowel rest with nasogastric suction, is usually necessary. Complications include pseudocysts, abscesses, thrombosis, and necrosis of intraabdominal vessels and organs.

Henoch Schönlein Purpura—also known as anaphylactoid purpura or nonthrombocytopenic purpura—is a vasculitis of unknown etiology. Children present with abdominal and joint pain and a characteristic rash. The rash classically begins as large patches of urticaria predominantly on the lower extremities but also on the arms and ears. The trunk is relatively spared. The rash then progresses to purpuric lesions, which become edematous, hence the term, palpable purpura. Gross hematuria and bloody stools also may be seen. Intussusception, as a result of edematous nubbins of intestinal mucosa acting as leading points, is a dangerous complication. Evaluation of the urine may reveal signs of a glomerulonephritis (proteinurea and hematuria); fortunately, this resolves without permanent renal damage in the vast majority of cases. Treatment with systemic steroids is useful for the child with severe GI symptoms but does not appear to help either the arthritis or nephritis. Nor does treatment appear to alter the natural course of the illness, which may last for 3 to 4 weeks. Fortunately, the prognosis in almost all children is uniformly excellent.