This office test is used to evaluate the inside of the uterine cavity. Using a thin plastic catheter that bypasses the cervix, we inject a saline solution into the uterus while imaging with a vaginal sonogram. This allows the physician to visualize any irregularities that might interfere with fertility (i.e. polyps, fibroids). It does not evaluate the tubes and is not the best test for diagnosing congenital abnormalities of the uterus such as a uterine septum.