Abdominal pain is 1 of the most common complaints in children, accounting for approximately 15% of all children evaluated in pediatric emergency units. Abdominal pain can be acute and sudden in onset or chronic with continual or intermittent symptoms. Most episodes of pain are benign and are usually self-limited. One study found that only 20% of all children evaluated in an emergency department for acute abdominal pain required surgical intervention, most often for appendicitis. Differentiating abdominal pain that requires prompt surgical intervention from pain due to nonsurgical conditions is often challenging, especially for infants and younger children. The evaluation and management of abdominal pain varies depending on the severity and character of the pain, associated symptoms, and age and sex of the child. The difficulties in diagnosis can be reduced by considering the most likely diagnosis based on the child’s age, the presence of associated symptoms, and the physical examination.
The sensation of abdominal pain is transmitted to the central nervous system via somatic and visceral afferent fibers. The visceral afferent system innervates the visceral peritoneum and its structures. Visceral pain localizes poorly, but pain originating from the stomach, duodenum, and pancreas generally localizes to the epigastrium; pain originating from the small bowel, colon, and spleen localizes to the periumbilical region; and pain originating from the rectosigmoid and bladder localizes to the hypogastrium. Renal or ureteral pain is usually localized to the flank. Gallbladder pain is often poorly localized but may localize to the right upper quadrant. Pain originating from the parietal peritoneum from inflammation or abdominal wall pain is well localized. Referred pain results from the convergence of visceral and somatic pain pathways in the spinal cord, so pain originating in abdominal viscera may be perceived as originating at a distant, well-isolated somatic location. For example, diaphragmatic irritation secondary to pancreatitis, a splenic hematoma, cholecystitis, or liver abscess may be interpreted as pain arising in the vicinity of the lower neck and shoulders because the diaphragm and shoulder pain pathways converge in the spinothalamic tracts at the C4 vertebra. Similarly, gallbladder inflammation may be sensed in the right infrascapular region, pancreatic pain may be sensed in the posterior flank, a migrating ureteral stone may be felt progressing toward the ipsilateral groin, and rectal and gynecologic discomfort may be sensed in the vicinity of the sacrum. Conversely, pain originating in somatic locations, such as the right pleural surface with pneumonia, may be perceived as originating in the lower abdomen because pain afferents from both regions converge at the T10 to T11 vertebrae.
CLINICAL MANIFESTATIONS AND DIFFERENTIAL DIAGNOSIS
Pain of sudden onset is likely associated with colic, perforations, and acute ischemia (eg, torsions, volvulus). Slower onset of pain generally is associated with inflammatory conditions such as appendicitis, pancreatitis, and cholecystitis. Colic results from spasms of a hollow muscular viscus (eg, biliary tree, pancreatic duct, gastrointestinal tract, urinary system, ...