Ultrasound of Endometrium

The normal endometrium changes in appearance as well as in thickness throughout menstrual cycle:

Menstrual & early proliferative phase - thin, brightly echogenic stripe comprising of basal layer, minimal fluid can be appreciated endovaginally in menstrual phase

Proliferative phase - trilaminar appearance; (i) outer echogenic basal layer, (ii) middle hypoechoic functional layer, (iii) an inner echogenic stripe at the central interface

Secretory phase - it is at its thickest up to 16mm, becomes uniformly echogenic, as the functional layer becomes edematous and isoechoic to the basal layer; there is through transmission and posterior acoustic enhancement noted