Overview Recurrent abdominal pain (RAP) is an abdominal syndrome with prominent symptoms, vague signs, and an insidious etiology. It is an episodic abdominal pain that occurs monthly for at least 3 months and can interfere with the normal activities of the child during severe episodes, but behaves normally during intervals. Recurrent abdominal pain is one of the most common clinical symptoms in children, and because of its recurrent attacks, conventional treatment often fails to achieve the desired effect, which affects the physical and mental health of children and the normal life of their families, thus becoming a clinical diagnosis and treatment problem. According to incomplete statistics, RAP accounts for more than 50% of children with abdominal pain in China, and it can appear before school age, but less frequently occurs before the age of 5 and after the age of 15, and frequently occurs during school age (10-12 years), with a prevalence of 10%-19.25% in this age group and a ratio of 5:3 between girls and boys. With the shift from the traditional bio-medical model to the bio-social-psychological model of disease exploration, the diagnosis and management of RAP in children has changed. Etiology and classification RAP is classified as organic or functional. In children younger than 2 years of age, RAP often has an organic disorder; whereas, in preschool and school-age years, the functional proportion increases. 1. Organic RAP: Common organic diseases include chronic constipation, parasitic infection, carbohydrate intolerance, genitourinary disorders, recurrent pancreatitis, upper gastrointestinal inflammation and peptic ulcer, inflammatory bowel disease, eosinophilic gastroenteritis, hepatobiliary disease, irritable bowel syndrome, abdominal migraine, hemolytic anemia, and lead poisoning. Gastrointestinal and genitourinary system diseases are the most common, accounting for about 1/3 of the cases. (1) Psychological factors: Children with RAP have special psychological manifestations, such as nervousness, repression, desire for love and care and pursuit of perfection, and may have factors such as parental divorce, family discord, fear of school and aversion to certain things. The survey showed that the incidence of anxiety and depression in RAP patients was significantly higher than that in the control group. (2) Autonomic dysfunction: vagus nerve hyperfunction, resulting in spasm of gastrointestinal smooth muscle, producing abdominal pain. (3) Visceral sensory hypersensitivity theory: children with RAP have lower pain values than normal children and have increased sensitivity to painful stimuli. (4) Gastrointestinal motility dysfunction: endogenous opioid (β-endorphin) activity increases during mental stress, which excites the smooth muscle of the gastrointestinal tract, causing prolonged gastric emptying, decreased propulsive peristalsis, increased anal sphincter tone, obstructed defecation, contraction of the sphincter of Oddi, and increased pressure in the gallbladder and bile duct. Pathogenesis It is currently believed that the pathogenesis of FAP is primarily visceral hyperalgesia. The patient’s abdominal pain may occur due to abnormalities in the downstream inhibitory nervous system of the brainstem or imbalances in inhibitory/excitatory neuromodulatory pathways, resulting in abnormal excitability of spinal nerves that regulate peripheral pain sensation and amplified nociception.FAP pain may be a central pain due to normal internal regulatory signals amplified in the central nervous system rather than abnormal function of the gastrointestinal tract itself. Trace memory: A painful stimulus that lasts for a long time can leave a trace in the CNS, which activates the recall of the original painful stimulus in the brain when the noxious stimulus acts on the same receptor area again. Clinical manifestations 1. recurrent fever above 38°C; 2. weight loss or no weight gain; 3. growth disturbance; 4. abdominal pain limited and deviated from the midline; 5. vomiting blood; 6. vomiting bile; 7. positive fecal blood or occult blood; 8. anemia; 9. increased sedimentation; 10. increased fecal antitrypsin. Treatment and prognosis 1. Treatment of organic RAP Treatment of the cause after definite diagnosis. 2. Treatment of functional RAP The fundamental treatment lies in a comprehensive treatment based on a good doctor-patient relationship, and excessive repeated examinations and misuse of antibiotics should be avoided. A good doctor-patient relationship includes sympathy for the patient, education of the patient, confirmation of the disease, repeated reassurance, and communication of treatment plans. (1) Psychotherapy: First of all, it is necessary to gain the trust of parents and children. Careful history taking, meticulous physical examination, necessary screening negative results, and patient explanation all help to relieve the psychological burden of parents and children. Encourage the child to adhere to normal studies and activities, and encourage school attendance for those who have dropped out of school. (2) Dietary treatment: Establish good dietary habits, increase the intake of fiber-containing foods, and eat less gas-producing foods; lactose-intolerant patients can switch to lactose-free milk powder. Develop regular bowel habits. (3) Drug symptomatic treatment: use antispasmodics, gastrointestinal stimulants, drugs to regulate the function of the plant nerves and tricyclic antidepressants, etc. (4) Other: biofeedback therapy, intestinal microecological agents and mucosal protective agents, traditional Chinese medicine, etc. (5) Establish a follow-up system to identify warning signs (symptoms and signs suggestive of organic RAP) in a timely manner, and to reexamine and diagnose any newly emerged conditions. Long-term follow-up can not only relieve the anxiety of parents and children, but also detect or exclude organic lesions over time. 3. Prognosis: 1/3 of functional RAP can be relieved within 5 years, 1/3 of children can continue to have symptoms into adulthood, and 1/3 can be combined with other symptoms. However, the vast majority do not affect normal life. The prognosis is not good for male children with a similar family history, for those with an initial age of less than 6 years, and for those with a history of more than 6 months prior to consultation. In contrast, the prognosis of organic RAP is related to its primary cause.