CHAPTER 53 ■ PAIN: ABDOMEN VINCENZO MANIACI, MARK I NEUMAN INTRODUCTION Abdominal pain is a common complaint of children who seek care in the ED Although most children with acute abdominal pain have self-limiting conditions, the presence of pain may herald a serious medical or surgical emergency The diverse etiologies include acute surgical diseases (e.g., appendicitis, intussusception, strangulated hernia, trauma to solid or hollow organ), intraabdominal nonsurgical ailments (e.g., gastroenteritis, urinary tract infection [UTI], gastric ulcer disease, gastroesophageal reflux disease), extra-abdominal conditions (e.g., pneumonia, pharyngitis, contusions of the abdominal musculature or soft tissue), systemic illnesses (e.g., “viral syndrome,” leukemia, diabetic ketoacidosis, vaso-occlusive crisis from sickle cell anemia), and, commonly, functional abdominal pain Making a timely diagnosis of an acute abdomen, such as appendicitis or volvulus, early enough to reduce the rate of complications, particularly in infants and young children, often proves challenging PATHOPHYSIOLOGY Abdominal pain can be stimulated by at least three neural pathways: visceral, somatic, and referred Visceral pain generally is a dull, aching sensation caused by distention of a viscus that stimulates nerves locally and initiates an impulse that travels through autonomic afferent fibers to the spinal tract and central nervous system The nerve fibers from different abdominal organs overlap and are bilateral, accounting for the lack of specificity to the discomfort Children perceive the sensation of visceral pain generally in one of three areas: the epigastric, periumbilical, or suprapubic region Somatic pain usually is well localized and intense (often sharp) in character It is carried by somatic nerves in the parietal peritoneum, muscle, or skin unilaterally to the spinal cord level from T6 to L1 An intra-abdominal process will manifest somatic pain if the affected viscus introduces an inflammatory process that touches the innervated organ Referred pain is felt at a location distant from the diseased organ and can be either a sharp, localized sensation or a vague ache Afferent nerves from different sites, such as the parietal pleura of the lung and the abdominal wall, share pathways centrally All three types of pain may be modified by the child’s level of