Hysterosonography, also known as a ‘saline infusion sonogram’, uses sterile saline to expand the uterine cavity, making it easier to obtain images of the uterine cavity and endometrium. This test is a useful tool when the subject is suffering from heavy menstrual bleeding despite normal ultrasound results. This procedure is also used to evaluate the extent of submucosal fibroids, but is a relatively invasive procedure.