The so-called “menstrual sensation” usually refers to premenstrual dysmenorrhea, which usually occurs about 2 days before menstruation and is related to increased uterine tension and spasmodic contractions, and is primary dysmenorrhea. It is normal for menstruation to be delayed for about 7 days, and may be related to staying up late, emotions, stress, excessive weight loss and other factors. In addition, dysmenorrhea but not menstruation may also be related to the following factors: I. Primary dysmenorrhea: 1. Pregnancy: As the embryo formed after the union of sperm and egg is laid and developed in the uterus, the endometrium at this time needs to maintain a certain thickness, which is conducive to the development of the embryo, so the endometrium is no longer shed and temporary physiological amenorrhea occurs. When patients who have had sex without contraception have delayed menstruation for more than 10 days or more and are not accompanied by abnormal vaginal discharge, abnormal bleeding and other symptoms, pregnancy is considered a factor and can go to the hospital for relevant tests to confirm the diagnosis; 2. PMS: PMS often appears about 1 week before menstruation, with symptoms such as fatigue, lower abdominal pain, breast tenderness and headache as the main manifestations, and some Patients can maintain it for several days to 2 weeks, and it peaks 2 days before menstruation. Because of the early onset, there is a time lag between the onset of menstruation and the official menstruation. If the symptoms of dysmenorrhea are more serious or accompanied by excessive menstrual flow, patients can go to the clinic; 3. Other factors: endocrine disorders caused by excessive weight loss, late nights, stress, emotional excitement and other factors, resulting in abnormal ovarian secretion, which can lead to delayed menstruation or even temporary amenorrhea. Therefore, if a patient has the “feeling of a period” but does not have a period, he or she can adjust lifestyle habits, soothe the mood and eat a healthy diet to relieve it. Patients with prolonged amenorrhea also need to seek professional medical help. Secondary dysmenorrhea: Vaginitis caused by various infections, or endometriosis, uterine fibroids, chronic pelvic inflammatory disease, cervical polyps and other diseases also often cause pain in the lower abdomen, manifesting as secondary dysmenorrhea, which may occur when the patient is not menstruating, so the pain is not accompanied by menstruation. Patients may also experience abnormal vaginal bleeding, increased discharge, and changes in the nature of the discharge, such as mucus, bloody, foamy, or changes in color such as yellow, yellow-green, or brown, which need to be brought to patients’ attention and should be promptly treated by a doctor.