Fluid collections in the cavity of the uterus in premenopausal women are usually associated with pregnancy. In a postmenopausal woman, fluid collection discovered on ultrasound may be a sign of uterine or cervical carcinoma, cervical stenosis with atrophic endometrium, or bleeding in women taking anticoagulants. Endometrial biopsy is useful in the evaluation of uterine fluid collection in the postmenopausal woman. (Breckenridge, Carlson, Goldstein).