Small abdominal pain in a 12-year-old child may be related to primary dysmenorrhea, urinary tract infection, urinary retention and so on. 1. Primary dysmenorrhea: if it is a 12-year-old girl with small abdominal pain, it may be primary dysmenorrhea during menstruation, which is related to abnormally high levels of prostaglandin in the endometrium. 2. Urinary tract infection: It may be a variety of pathogens, such as viruses and bacteria, which enter the body through different ways, grow and multiply in the urinary tract. This leads to the appearance of bladder and urethra infections, which may show symptoms such as lower abdominal pain, painful urination and frequent urination. 3. Urinary retention: it may be the obstruction of the urethra, for example, when the urinary tract stone stays in the bladder opening, it may cause partial obstruction of the urethra. This leads to urinary retention caused by a full bladder, which can also lead to small abdominal distension. Small abdominal pain in 12-year-old children can also be seen in other causes, it is recommended to consult a doctor in a timely manner, follow the doctor’s instructions to carry out relevant examinations, with the help of the doctor to clarify the cause, and targeted treatment or treatment.