Unclean vacation may not be related to poor uterine contraction. Unclean vacation, clinically considered may be related to the following factors: First, the cervical opening is too small, which may cause poor contraction of the uterus. The uterine lining can not be peeled off as soon as possible, and at the same time cause the accumulation of fluid in the uterine cavity, which is manifested as unclean vacation. Endometrial polyps or submucosal fibroids may also cause long duration of menstruation, which may be manifested as unclean menstruation. Third, there is an intrauterine device, due to the stimulation of the device, affecting the stripping of the uterine lining, manifested as unclean menstruation. Fourth, cesarean section incision healing is poor, affecting the lower segment of the uterus contraction is not good, manifested as unclean menstruation. So there are many clinical reasons for unclean menstruation, it is best to do hysteroscopy examination.