If the menstruation comes for 10 days and the amount is relatively small, it is an abnormal phenomenon. The most common reasons are the following: 1, endocrine disorders caused by the menstrual period is longer, and the amount is relatively small. 2, pregnancy. In the clinic, after someone is pregnant, there will be irregular vaginal bleeding, which will be mistaken for menstruation and ignored as pregnancy. It is recommended to go to the hospital to draw blood to check the blood HCG, if the blood HCG>10mIU/mL is the case of pregnancy.3, endometrial lesions. If necessary, do ultrasound examination, can understand the situation of the uterine lining. If the endometrium has abnormal echogenicity, or irregular echogenicity, it is recommended to do diagnostic scraping, and send the scraped out tissues to the pathology laboratory, and the pathology diagnosis will prevail.