In postmenopausal bleeding, an endometrial thickness of less than 4 mm on transvaginal ultrasound most likely indicates what endometrial condition?

• A. Atrophic endometrium
• B. Endometrial carcinoma
• C. Endometriosis
• D. Uterine fibroids

Answer: (A)

A thin endometrial stripe on transvaginal ultrasound in a postmenopausal patient with bleeding points to endometrial atrophy from estrogen withdrawal. When the lining is under about four millimeters, the likelihood of endometrial cancer is very low, so atrophic endometrium is the most likely finding. Endometrial carcinoma tends to present with a thicker endometrium on ultrasound and a higher risk with a thicker stripe. Endometriosis is a condition seen mainly in premenopausal women and does not explain a thin postmenopausal endometrium. Uterine fibroids can cause bleeding but do not specifically produce a uniformly thin endometrial lining; thickness alone isn’t diagnostic for fibroids.