Transvaginal ultrasound is a reliable way of excluding endometrial carcinoma. When thin and distinct it is far superior to blind endometrial sampling whether by suction piston biopsy or actual D&C. In such cases it can reduce the expense, discomfort, and risk of endometrial sampling. Recently The American College of Obstetricians and Gynecologists has endorsed endometrial thickness < 4mm as so reliable in excluding endometrial cancer that in such patients endometrial biopsy for tissue histology is deemed unnecessary.

Unfortunately, many clinicians have assumed that because an endometrial echo < 4-5mm in postmenopausal patients with bleeding is good, that endometrial thickness > 5mm discovered incidentally in patients without bleeding is abnormal and should warrant further investigation. There are fewer data on such patients. The incidence of quiescent endometrial polyps or old submucous myomas that result in endometrial "thickening" when viewed as part of an incidental imaging study, has not established. Some data indicate that 10-17% of postmenopausal patients have a "thickened" endometrial echo on transvaginal ultrasound. Data exists that such endometrial thickening in non bleeding patients will have an incidence of complex hyperplasia or endometrial carcinoma that approaches 0%. The complications of performing operative hysteroscopy on such patients, has been reported as high as 3.6%. Thus while TV/US < 4mm in a patient with postmenopausal bleeding reliably excludes carcinoma, the existence of an incidental finding of endometrial thickening in postmenopausal patients without bleeding has not been prospectively validated and need not automatically result in obtaining tissue for histologic evaluation.