Abdominal Pain
Claudio Morera
I. Description of the problem.
A. Definition. Chronic abdominal pain (CAP) is episodic or continuous abdominal pain for at least 2 months. It might or might not interfere with daily functioning. Recurrent abdominal pain (RAP) is a clinical description and not a diagnosis. To avoid confusion from initial descriptions of the problem, it is better called CAP and it can be organic abdominal pain and functional abdominal pain (FAP).
B. Epidemiology.
CAP can be 2%-4% of all pediatric visits.
Weekly abdominal pain is reported in 13% of middle school and 17% of high school students.
FAP prevalence in pediatric gastroenterology, using very strict criteria, has been reported in 7.5%.
C. Etiology.
1. Organic abdominal pain. Although the list of possible etiologies is large, only 10%-25% of children presenting with CAP have an identifiable organic etiology. Table 21-1 shows a list of disorders that can present as CAP that can mimic FAP.
2. FAP. FAP is the main cause of CAP in the pediatric age group. It used to be an exclusion diagnosis; currently diagnostic criteria have been developed that allows a positive diagnosis. A combined interaction of altered gastrointestinal (GI) motility, visceral perception, and psychological factors is the main pathophysiologic mechanism. The biopsychosocial model provides the conceptual basis to FAP, including such potential etiologies as genetics, postinfectious, certain foods like sorbitol and other carbohydrates, psychological stress, school stress, other anxiety, etc. The concept of health and disease as well as coping skills also may play a role. Parents of patients with FAP have more GI complaints, anxiety, and somatization. Their understanding and acceptance of the biopsychosocial concept is associated with recovery.
II. Making the diagnosis of FAP. The main purpose is to establish the diagnosis of FAP, which was an exclusion diagnosis, but clinical diagnostic criteria have been developed to make a positive diagnosis of FAP with minimal workup (Rome III Criteria, Table 21-2)
A. Signs and symptoms. The abdominal pain is typically periumbilical, lasts 30-60 minutes, and occurs during the day (rarely awakening the child from sleep). It might or might not be associated with alterations in daily functioning. In most cases, the pain pattern cannot differentiate organic from functional, but the presence of red flags (Table 21-3) has a high positive predictive value for organic disease.
If there is some loss of daily functioning and additional somatic symptoms (headaches, limb pain, or difficulty sleeping), FAP syndrome is present.
B. Differential diagnosis. The initial differentiation is between organic and FAP. Other functional bowel disorders associated with pain should also be considered, that is, irritable bowel syndrome, abdominal migraine, functional dyspepsia, etc.
C. History: key clinical questions.
1. “When did the abdominal pain begin? How often does it occur? Where does it hurt? Has the child locate the area by pointing with one finger?” Establish origin point in time (at least 2 months), frequency (at least once a week), and localization.
2. “Has there been weight loss?” Investigation of red flags.
3. “How is the stooling pattern?” Constipation or diarrhea must be investigated as a potential red flag as well as other functional GI disorder like irritable bowel syndrome.
4. [To both parent and child] “What do you think is going on? What do you do when the pain starts or to control it? How does it interfere with daily functioning, school missing, etc? Are there similar symptoms or other functional disorders in family members?” It is important to start with open questions and let both parents and patient elaborate. We need to determine how much the symptoms impair functioning, what is the reward system in the family, what behaviors are reinforced (health or disease), what are
the fears and prior experiences with chronic pains. The objective is to understand the family concept of health and disease, their understanding of the biopsychosocial concept of disease, coping skills, and presence of anxiety, depression or somatization in the family as well as in the child
Table 21-1. Organic abdominal pain that can mimic functional
Carbohydrate malabsorption
Parasitic (Giardia)
IBD
Constipation
Allergic enteropathy
Celiac disease
Antibiotic-associated diarrhea
Peptic ulcer
GERD
Eosinophilic esophagitis
Crohn’s disease
Cholelithiasis
Pancreatitis
IBD, inflammatory bowel disease; GERD, gastroesophageal reflux disease.
D. Behavioral observations. Observe parent-child interaction (is the patient allowed to answer questions, is he or she treated as if he or she was younger, etc?) and reaction to pain complaints. Observe developmental state of the patient as well as body posture, dressing, etc.
E. Physical examination. A complete physical examination is essential. Any area not examined at this time should be clearly noted so it can be examined in the future.
F. Laboratory evaluation. If the history and physical examination suggest a specific etiology, appropriate tests should be ordered. Otherwise, the initial laboratory evaluation should be quite limited and is oriented to rule out most organic conditions (Table 21-4).
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