To diagnose the cause of abnormal menstrual clots, a doctor may ask about signs and symptoms, order blood or imaging tests, carry out a. Some things about your period -- like heavy flow and type of cramps -- offer clues to problems in your body. Find out what's normal and when to. Here, experts explain why menstrual blood clots happen and when they warrant image. Is My Heavy Period Normal or Not? A Gyno Explains.