Endometrial cancer and ultrasound: why measuring endometrial thickness is sometimes not enough

Endometrial cancer is the commonest cancer of the female genital tract in the developed world. Ultrasound measurement of endometrial thickness is commonly used to triage patients with postmenopausal bleeding for histological sampling. The sensitivity of ultrasound in diagnosing endometrial cancer is high, but it has a small, well-defined false-negative rate. In this report we describe two cases, with histological confirmation, of postmenopausal women without any vaginal bleeding, who were subsequently diagnosed with advanced endometrial cancer. They were found to have a thin, normal endometrium on ultrasound. In both cases, histological examination was suggestive of endometrial cancer originating from foci of adenomyosis. These findings suggest that a proportion of the false-negative diagnoses of endometrial cancer on ultrasound could be caused by the disease being confined to the myometrium rather than as a result of suboptimal performance of ultrasound examination.