Symptom-Based Diagnosis in Pediatrics (CHOP Morning Report) 1st Ed.

CHAPTER 7. ABDOMINAL PAIN

MARINA CATALLOZZI

DEFINITION OF THE COMPLAINT

Abdominal pain is a common complaint in pediatrics and has an extensive list of possible causes, not all gastrointestinal in etiology. Additionally, the etiology may be acute and life-threatening or more chronic in nature. The patient’s clinical presentation, history, and physical examination along with directed testing usually elucidate the etiology and help clarify the treatment course.

Abdominal pain is usually stimulated by one of three pathways: visceral, somatic, or referred. Visceral pain is caused by a distended viscus (i.e., one of the organs of the body) that activates a local nerve and sends an impulse that travels through autonomic afferent fibers to the spinal tract and central nervous system. Precise localization of visceral pain is often difficult and frustrating because there are very few afferent nerves that travel from the viscera and the nerve fibers frequently overlap. Visceral pain is generally felt in the epigastric region, the periumbilical region, or the suprapubic area. Somatic pain, because it is carried by somatic nerves in the parietal peritoneum, muscle, or skin, is usually well localized and sharp. Referred pain, defined as abdominal pain perceived at a site remote from the actual affected viscera, can either be sharp and localized or diffuse. There is a great deal of individual variability in the experience of pain so that neuroanatomic, neurophysiologic, pathophysiologic, environmental, and psychosocial factors all play a part in the expression of pain. The frequency of the chief complaint of abdominal pain necessitates categorizing the presentation of abdominal pain into the following: acute abdominal pain and chronic abdominal pain.

In the case of acute abdominal pain, a patient or parent is usually able to pinpoint the onset of the pain to an event or time of day. If the pain is mild initially, it often becomes progressively worse and eventually interferes with sleep and normal activities. Other than intussusception (when one part of the intestine slips into itself), acute abdominal pain that requires surgical intervention does not recur and is not relieved without some intervention. Nausea, vomiting, diarrhea, fever, and anorexia often accompany acute abdominal pain. Patients most often appear acutely ill and position themselves to protect the abdomen from further examination. Chronic abdominal pain is defined as pain that lasts 2 or more weeks. Chronic abdominal pain does not usually require surgical intervention. Although formal definitions and guidelines exist, the definition basically includes any child who has abdominal pain with multiple episodes (minimum of three) over a long period (at least 3 months) without a known cause, for which the family seeks medical attention, and which interferes with the child’s ability to function. In the past, the term recurrent abdominal pain was used as well, but in 2005 the American Academy of Pediatrics Subcommittee on Chronic Abdominal Pain suggested that the term be replaced with functional abdominal pain as it is thought to be the most common cause of chronic abdominal pain. Functional abdominal pain has no pathologic root. Because of the frustration for the family and child, as well as the extensive differential diagnosis for this problem, a consistent approach is vital. The approach must include a thorough history, arguably the most important component, physical examination, laboratory testing, imaging studies, and empiric interventions.

COMPLAINT BY CAUSE AND FREQUENCY

It is vital to remember that abdominal pain, although a frequent complaint, is not in itself a diagnosis, and a thorough evaluation of this symptom is required to determine the cause. The causes of abdominal pain in childhood vary by age (Table 7-1), can be based on whether the abdominal pain is acute or chronic in nature (Table 7-1), and can also be grouped by etiology (Table 7-2).

TABLE 7-1. Causes of abdominal pain by age.

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TABLE 7-2. Causes of abdominal pain in childhood by etiology.

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CLARIFYING QUESTIONS

Accurate diagnosis in a child with abdominal pain requires a thorough history and physical examination. There must be consideration of the type and location of pain to create a working differential to approach the individual patient with abdominal pain. The following questions may be helpful in arriving at a diagnosis:

• When did the pain begin and how long has it lasted?

— The determination of acute or chronic pain is vital in considering the possible etiologies of the pain, identifying a patient who requires surgical intervention (i.e., intestinal obstruction, acute appendicitis, malrotation and midgut volvulus, Meckel diverticulum, incarcerated inguinal hernia, hypertrophic pyloric stenosis, trauma, Hirschsprung disease), and finally determining any other life-threatening causes of abdominal pain that do not require surgical intervention (i.e., intussusception, severe gastroenteritis, toxic overdose, sepsis, hemolytic uremic syndrome, diabetic ketoacidosis, myocarditis, peptic ulcer disease with perforation, fulminant hepatitis, ectopic pregnancy, pelvic inflammatory disease with tuboovarian abscess). Although gastroenteritis is the most common cause of acute pain and constipation considered the most common cause of chronic pain, other etiologies must be ruled out.

While an infant will frequently display pain as a behavior change (i.e., poor oral intake, irritability, inconsolable crying), older children can verbalize the character of the pain. For diagnoses such as irritable bowel syndrome, where the chronicity of the pain is an important feature of the diagnosis, the duration of pain is also vital. Additionally, with chronic pain, the timing of the pain is key. For example, pain that awakens a child from sleep suggests peptic disease whereas pain that occurs during dinner is often associated with constipation. Additionally, paroxysms of pain, where the child has 20-minute intervals of being well in between inconsolability, is classically seen with intussusception.

• What is the location of the pain?

— Even when abdominal pain seems localized, a thorough examination must be performed to rule out other nongastrointestinal causes of the pain. Certain locations may herald specific disease processes. Perhaps, the most important of these is the association of appendicitis with acute pain in the right lower quadrant (even more specifically, tenderness over McBurney point). While appendicitis is the most common cause for emergency surgery (apart from trauma) in children, delayed diagnosis often occurs in children because a progressing disease process often results in the absence of the classic clinical findings. Acute appendicitis often does not have pain as the first symptom, but other surgical emergencies that are potentially life-threatening and catastrophic do (e.g., malrotation with volvulus, intussusception, ovarian torsion). The classic pattern associated with acute appendicitis of periumbilical visceral pain that travels to the right lower quadrant with subsequent nausea, vomiting, and anorexia is far less common in children younger than 12 than it is in adults. For infants, vomiting, pain, diarrhea, fever, irritability, grunting, and refusal to walk or limp are just a few of the nonlocalizing symptoms that lead to misdiagnosis and high rates of intestinal perforation. While the rates are low in children ages 2-5 years of age (<5%), the more classic signs and symptoms of right lower quadrant pain, vomiting, and fever are more common. As the incidence of appendicitis increases in school-aged children and adolescents, when the incidence peaks, so do the more common symptoms of vomiting, anorexia, and right lower quadrant pain.

Right lower quadrant pain can also be associated with Crohn disease, mesenteric adenitis associated with group A streptococcal pharyngitis, bacterial enterocolitis (particularly Yersinia enterocolitica and Campylobacter jejuni), Meckel diverticulitis, and intussusception. Right upper quadrant pain should prompt investigation for cholecystitis, cholelithiasis, Fitz-Hugh-Curtis syndrome, and right lower lobe pneumonia. Left upper quadrant pain often indicates splenomegaly, hemolytic crisis, or splenic trauma. Epigastric pain may indicate peptic disease (such as peptic ulcer disease, esophagitis secondary to gastroesophageal reflux disease, gastritis), or pancreatitis. Suprapubic pain can suggest a urinary tract infection (UTI), menstrual disorders, or pelvic inflammatory disease. Some diagnoses commonly have radiation of pain and should always be investigated—back pain can be seen with pancreatitis or UTI, and gallstones frequently are associated with shoulder pain.

• Has there been a change in stool pattern, blood in the stool, or is the pain relieved with defecation?

—Questions regarding stool pattern and consistency are important in both acute and chronic abdominal pain. In the acute setting, diarrhea early in the history can point toward an infectious etiology such as viral or bacterial gastroenteritis. Additionally, examination of the rectum and stool gives important diagnostic information. While bloody mucoid or currant jelly stools are seen late in the course of intussusception, hemoccult positivity can be seen earlier.

For more chronic etiologies, such as constipation, irritable bowel syndrome, and inflammatory bowel disease, these questions can also clarify the diagnosis.

• Is there associated emesis?

—While vomiting can occur with several of the etiologies of abdominal pain, vomiting in the absence of abdominal pain usually indicates upper intestinal tract disease. Bilious emesis heralds obstruction.

• Can the examination reveal the etiology of the abdominal pain?

— When the diagnosis is unclear and surgical intervention remains a possibility, reassessment and reexamination by the same clinician is an important part of the evaluation. This is particularly important with diagnoses such as appendicitis where there is no definitive piece of historical examination or laboratory data that will make the diagnosis.

Certain physical examination findings suggest the diagnosis—Cullen sign (discoloration of the umbilicus) or Grey Turner sign (discoloration of the flank) with hemorrhagic pancreatitis; Murphy sign (pain with deep palpation of the right upper quadrant) with gallbladder disease; and Rovsing sign (pain in the right lower quadrant with palpation of the contralateral side) in appendicitis.

• Is there an ingestion or toxin exposure?

— Ingestion of certain medications or heavy metals (e.g., lead) can lead to chronic abdominal pain.

• Has there been a recent or preceding respiratory illness?

— An upper respiratory infection frequently precedes intussusception as a mesenteric lymph node is thought to act as the lead point.

• Is there any significant family history?

— This can be a key piece of history in diseases such as inflammatory bowel disease, familial Mediterranean fever, and cystic fibrosis.

• What is the child’s weight and height?

— Failure to thrive indicates a more chronic disease such as inflammatory bowel disease.

The following cases represent less common causes of abdominal pain in childhood.