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Definitions
"Bilayer" thickness: measurement in millimeters of both layers of endometrium in anteroposterior dimension.
Endometrial "width": measurement in millimeters of distance of endometrium in thickest coronal dimension.
Sonohysterography: assessment of endometrial surface using infused saline.
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Over the past several years, transvaginal sonography (TVS) of the endometrium has assumed an integral role in the evaluation of women with possible endometrial disorders.1 Transvaginal sonography allows detailed delineation of endometrial thickness and texture in most patients. The sonographic findings have important implications in determining which patients need endometrial biopsy or dilatation and curettage, observation, or alteration of medication. The more extensive use of sonohysterography (SHG) (fluid instillation into the endometrial lumen) has also greatly enhanced sonographic evaluation of patients with endometrial disorders. This chapter discusses and illustrates the clinically important applications of TVS in the evaluation of the endometrium. It also discusses some of the technical factors and limitations of the technique.
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One of the most common disorders evaluated by gynecologists is unexpected or excessive uterine bleeding. It should be emphasized that only 10% to 15% of postmenopausal women who present with postmenopausal bleeding have endometrial cancer; the vast majority have bleeding secondary to benign disorders such as atrophy or hyperplasia.2 The role of sonography is to determine which patients can forgo endometrial biopsy and to monitor endometrial changes in patients receiving tamoxifen or other forms of hormone replacement therapy (HRT). Approximately 30% of women receiving combined HRT experience bleeding. It is the role of TVS to determine which patients need biopsy, dilatation and curettage, alteration in their medicines, or observation.
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Although endometrial cancer is more common than ovarian cancer, this disease is associated with far less mortality. This is clearly related to the fact that one of the earliest signs of endometrial cancer is vaginal bleeding. In addition, endometrial cancer is usually still confined to the uterus when the patient presents, whereas two-thirds of patients with ovarian cancer have extensive disease at time of presentation (see Chapter 35 on early detection of ovarian and endometrial cancer).
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It is important conceptually to differentiate causes of uterine bleeding in the premenopausal from the peri- or postmenopausal woman. In the woman of child-bearing age, bleeding is usually associated with anovulatory cycles. This is typically related to poor corpus luteum function and support of endometrium with progesterone. Fibroids are also a very common cause of bleeding in this age group. It is thought that fibroids may denude the endometrial surface, resulting in excessive bleeding. Postmenopausal women have bleeding due to a variety of disorders. These include atrophy, hyperplasia, polyps, cancer, and fibroids. Atrophy is the most common cause of bleeding and is related to excessive thinning of the endometrium, making it friable and prone to bleeding. Sonographic detection of a polyp by TVS with or without SHG enables its hysteroscopic removal and cure of bleeding. Conversely, endometrial biopsy ...