Menstruation delayed 13 days or a single bar, indicating that there is no pregnancy, delayed 13 days is an abnormality, may be caused by endocrine disorders, caused by delayed menstruation for a number of reasons, such as changes in lifestyle, or travel, life and work stress or exams and so on, will cause menstruation delay. If your period is delayed for 13 days, it is recommended that you have an ultrasound examination to find out the thickness of the uterine lining. If the lining of the uterus is thickened, you can be given progesterone to adjust the menstrual cycle, and it is generally recommended that you have a hormone level examination 2-4 days after your period to find out the function of the ovaries and the reason for the delayed menstruation. If the menstrual period is delayed occasionally, the hormone 6 test can be left out for the time being. If the period is delayed again next time, it is still recommended to try to have the hormone level test done.