Menstruation Menstruation cyclic endometrium sheds and bleeds due to cyclic ovulation Mense 1.Endometrium is sloughed (progesterone withdrawal) 2. Nonclotting menstrual blood mainly comes from artery(75%) 3. Interval: 24-35 days(28 days). duration: 2-3 days. the first day of menstrual bleeding is considered by day 4. Shedding: 30-50 mlMenstruation • Menstruation cyclic endometrium sheds and bleeds due to cyclic ovulation • Mense 1. Endometrium is sloughed (progesterone withdrawal) 2. Nonclotting menstrual blood mainly comes from artery (75%) 3. Interval: 24-35 days (28 days). duration: 2-6 days. the first day of menstrual bleeding is consideredy by day 1 4. Shedding: 30-50 ml