Doctors use an important blood test called a complete blood count, or CBC for short, to measure the number of each blood cell in your blood sample. If the CBC shows a low number of red blood cells, white blood cells, or platelets, your doctor may look at the cells under a microscope.
In a typical menstrual cycle, estrogen made by the maturing ovarian follicle causes the glands to grow and the endometrium to thicken (partly through an increased blood supply).This thickening of the uterine lining is called the proliferative phase of the menstrual cycle.n a typical menstrual cycle, estrogen made by the maturing ovarian follicle causes the glands to grow and the endometrium to thicken (partly through an increased blood supply).
One usually predominates and ruptures mid-cycle, liberating the egg. When the lining of the uterus is shed, bleeding occurs and clots form. If the uterus holds onto the clots, they will break down and the blood darken, resulting in a dark menstrual flow.