An endometrial thickness of 19mm is probably in the normal range. The thickness of the endometrium of 19mm depends on what period of menstruation it is. If it is after ovulation and before menstruation, an endometrial thickness of 19mm is a normal physiological phenomenon. A clinical ultrasound suggestive of an endometrial thickness of 19 mm may indicate the onset of menstruation or early pregnancy, both of which may cause an endometrial thickness of 19 mm. The thickness of the endometrium varies with the menstrual cycle and may cause thickening of the endometrium before menstruation or during pregnancy, and before fertilization of the egg. An endometrial lining of 10 mm is abnormal if it is just after menstruation. Because the endometrium is shed just after menstruation, the endometrium should be between 4-6 mm at this time. A thick endometrium indicates the possibility of endometrial lesions.