ENDOMETRIAL ATROPHY WITH POLYP
Postmenopausal Endometrium: Several studies have shown that patients with postmenopausal bleeding and an endometrial measurement of less than 5 mm, are considered normal. Other studies have assessed the endometrium in the asymptomatic postmenopausal population, and found that a measurement of less than 9mm is considered normal. Patients on sequential hormone replacement therapy (HRT) have a changing endometrial appearance on ultrasound, which is similar to the premenopausal population. Recommendations based on endometrial thickness:
less than or equal to 4mm
bleeding = probably atrophy, no biopsy necessary
no bleeding = normal
bleeding = biopsy
no bleeding = normal
greater than 8 mm
sequential hormones = rescan early or late in cycle
still > 8 mm = biopsy
no hormones = biopsy
In summary, an endometrial thickness greater than 4 mm in the bleeding postmenopausal woman and greater than 8 mm in the asymptomatic postmenopausal woman, requires endometrial sampling.
Endometrial Atrophy: The majority of postmenopausal women that experience uterine bleeding has endometrial atrophy. This is diagnosed with an endometrial stripe that is thin and measures less than 5 mm on transvaginal ultrasound. In these patients no further work-up or therapy is necessary. When there are cystic changes present it is called cystic atrophy, which is very similar in appearance (other than thickness) to cystic hyperplasia.
Endometrial Polyp: Polyps are common lesions that are frequently seen in perimenopausal and postmenopausal women. They may cause uterine bleeding, although most cases are asymptomatic. If present in menstruating women, symptoms may include intermenstrual bleeding, menometrorhagia and possibly infertility. These lesions may be pedunculated or broad based, 20% are multiple and if they have a long stalk, they may protrude into the cervix or the vagina. Sonographically, polyps may appear as nonspecific echogenic endometrial thickening, which may be diffuse or localized. They may also appear as a focal, round, echogenic mass within the endometrial cavity. This appearance is much more identifiable when there is fluid within the endometrial cavity. In ultrasound this is achieved with sonohysterography, which is an ideal technique to demonstrate polyps. It is also valuable to differentiate submucousal leiomyomas from endometrial polyps. Polyps are seen arising from the endometrium whereas a normal layer of endometrium is seen overlying the submucosal fibroid. Histologically, polyps are localized overgrowths of endometrial tissue covered by epithelium. They contain variable numbers of glands, stroma, and blood vessels. Malignant degeneration is uncommon, but cystic degeneration can be seen, especially if the polyp is large.
Endometrial Hyperplasia: This entity is a common cause of abnormal uterine bleeding. It is defined as a proliferation of glands of irregular size and shape, with an increase in the gland/stroma ratio when compared to the normal proliferative phase endometrium. Sonographically, the endometrium is usually thick and echogenic, with well defined margins. Small cysts may be seen within the endometrium in cystic hyperplasia, and is similar to the appearance of cystic atrophy and cystic degeneration of polyps. Histologically, endometrial hyperplasia can be divided into two types, one with atypia and one without. The type with atypia has been shown to progress to endometrial carcinoma in 25% of cases, while in hyperplasia without atypia, less than 2% will progress to carcinoma. Hyperplasia develops from unopposed estrogen stimulation. In perimenopausal and postmenopausal women, was usually due to estrogen only HRT regimens (no longer widely used) while during the reproductive years, it is seen in women with persistent anovulatory cycles, polycystic ovarian disease and obese women who have increased production of endogenous estrogen.
Endometrial Carcinoma: Endometrial carcinoma is the most common gynecologic malignancy in North America, and its incidence is on the rise. 75%-85% of endometrial cancers occur in postmenopausal women. The most common presentation is uterine bleeding, although only 10% of those with postmenopausal bleeding have endometrial carcinoma. Sonographically, a thickened endometrium must be considered cancer until proven otherwise. The thickened endometrium may be well defined, uniformally echogenic and indistinguishable from hyperplasia or polyps. Cancer is more likely when the endometrium has an inhomogeneous echotexture with irregular or poorly defined margins. Cystic changes are more commonly seen in the other entities discussed but can also be seen in carcinoma. Although certain sonographic appearances tend to favor benign or malignant etiology, there are overlapping features, and endometrial biopsy is usually required for a definitive diagnosis.