How to determine if you are pregnant when your period hasn't arrived

Patient's question:

Hello
I would like to ask how to determine if I am pregnant when my period hasn't come for more than a month.
Also, what is the function of the hymen?

Doctor's answer:

After reaching sexual maturity, females experience menstruation, and menstrual blood is expelled from the body through the opening in the hymen. If there is no such opening in the hymen, menstrual blood cannot be expelled smoothly from the body. This phenomenon is known as "hymenolysis" in medicine. If menstrual blood accumulates in the vagina for a long time, it can flow upwards into the uterine cavity, fallopian tubes, or even into the abdominal cavity, causing abdominal infection and resulting in abdominal pain.