There are many reasons why menstruation is not clean after more than 10 days, as follows: 1. If you have had sex in the recent month and have not done a good job of contraception, first of all, we must exclude the abnormal bleeding caused by unwanted pregnancy or even ectopic pregnancy; 2. If you have endometrial polyps, cervical polyps, or even endometrial thickening or submucosal fibroids, it may lead to incomplete menstruation; 3. If you have had a cesarean section and formed a uterine diverticulum, you may also experience incomplete menstruation; 4. If you have recently had excessive mental stress or stayed up late or had an irregular diet, it may also affect ovulation and lead to incomplete menstruation; 5. If you have abnormal thyroid function or luteal insufficiency, or even endocrine disorders such as polycystic ovary syndrome, you may also have this symptom.