A 14-year-old girl whose period has not left after 16 days may be related to physiological factors such as stress and improper diet, and also to pathological factors such as endometritis, endometriosis and adenomyosis. 1. Physiological factors: for some 14-year-old girls, the recent high pressure of study, poor diet, emotional fluctuations, etc. can be induced by the phenomenon of 16 days of menstrual period has not gone. 2. Endometritis: the disease is related to pathogen infection, poor sexual hygiene, etc. Typical symptoms of patients include lower abdominal pain, leukorrhea, increased menstrual flow, prolonged menstrual period, and so on. 3. Endometriosis: the disease is mainly related to the reverse flow of menstrual blood, heredity and other factors. Common symptoms include dysmenorrhea, increased menstrual flow, prolonged menstrual period, infertility, etc., and the phenomenon that the menstrual period has not left after 16 days. 4. Adenomyosis: the cause of the disease is not clear, may be related to the operation of the uterine cavity, endometrial inflammation and so on. If a 14-year-old girl suffers from this disease, the symptoms of 16 days of menstrual period have not gone. There are many reasons why a 14-year-old girl’s period has not left after 16 days, and it is recommended to consult a doctor in time.