Fluid-contrast Ultrasound or FCU can reveal the texture of the uterine lining (endometrium) and any abnormalities such as polyps or fibroids by measuring the thickness of the endometrium. An ultrasound wand is implanted in the vagina and a tiny catheter is introduced through the cervix into the uterus. Sterile fluid is progressively administered into the uterine cavity through the catheter, and the area is imaged using ultrasound.