Endometrial polyps are fairly common lesions that can occur at any age. They can be pedunculated or broad-based, are generally benign, and, if benign, have little potential to become malignant. In a woman of menstrual age, polyps can cause intermenstrual bleeding, menorrhagia (heavy menstrual bleeding), or infertility. In the postmenopausal woman, the most common symptom of polyps is vaginal bleeding.

When a woman presents with abnormal vaginal bleeding, endometrial tissue sampling using either a suction catheter (“office endometrial biopsy”) or dilation and curettage is often performed. These sampling techniques, however, can miss polyps entirely because they blindly sample a portion of the endometrium. Ultrasound and saline infusion sonohysterography (SIS) can be used to detect polyps, after which the polyps can be resected under hysteroscopic or sonographic guidance.

On ultrasound, endometrial polyps are either homogeneously echogenic (Figure 30.1.1) or complex lesions with echogenic tissue and one or more cysts (Figure 30.1.2). If blood or secretions are present in the uterine cavity, the polyp appears as a focal mass outlined by fluid (Figure 30.1.3). Color Doppler of a polyp typically reveals a single feeding vessel (Figures 30.1.1 to 30.1.3).

A polyp should be suspected when ultrasound demonstrates a focal area of endometrial thickening, and should be included in the differential diagnosis when ultrasound demonstrates diffuse endometrial thickening. In either of these situations, the diagnosis can be

confirmed using SIS, which depicts polyps as focal projections of endometrial tissue into the saline-filled uterine cavity (Figure 30.1.4). 3D ultrasound can also assist in definitively diagnosing uterine polyps (Figure 30.1.5).

When an endometrial polyp is present, ultrasound is most likely to detect it if the surrounding endometrium is thin or hypoechoic. Thus, polyps are most easily detected
in a postmenopausal woman or during the proliferative stage of the menstrual cycle in a premenopausal woman. They are most likely to be missed during the secretory phase of the menstrual cycle, when they may be indistinguishable from the normal thick echogenic endometrium.

Polyps can be pedunculated within the endometrial cavity and can be propelled toward the cervix by uterine contractions. Sometimes, the polyp may prolapse through the cervix and become visible on speculum examination. Blood flow in the stalk to the prolapsing polyp can be imaged with color Doppler (Figure 30.1.6).

When the endometrium is thickened and heterogeneous with many tiny cystic spaces, the differential diagnosis includes a large polyp, endometrial hyperplasia, and cancer. Color Doppler imaging is helpful in determining the diagnosis, since polyps will have a single feeding vessel (Figure 30.1.7), while hyperplasia and cancer are typically fed by multiple small vessels.

Endometrial hyperplasia refers to abnormal proliferation of the endometrial glands. It is usually caused by unopposed estrogen stimulation, which can result from estrogen given as hormone replacement therapy, hormonal disorders (e.g., polycystic ovary syndrome), or estrogen-producing tumors. Endometrial hyperplasia can also occur in patients treated for breast cancer with selective estrogen-receptor modulators such as tamoxifen.

Hyperplasia is usually a diffuse endometrial process. It can occur with or without cellular atypia. If cellular atypia is present, there is a risk of progression to endometrial carcinoma. The risk is far lower in the absence of atypia.

Endometrial hyperplasia can occur in women of any age. It generally presents with abnormal vaginal bleeding and is among the most common causes of such bleeding.

The typical sonographic appearance of endometrial hyperplasia is diffuse, as opposed to focal, thickening of the endometrium. The thickened endometrium is usually homogeneous in echogenicity (Figure 30.2.1), but it may have multiple small cysts (Figure 30.2.2). The latter appearance is most commonly encountered in cases of endometrial hyperplasia that develop in response to treatment with tamoxifen. With tamoxifen-induced endometrial hyperplasia, cysts may also be seen at the endometrial–myometrial junction (Figure 30.2.3).

Endometrial hyperplasia is best detected when the normal endometrium is expected to be thin: in a premenopausal woman during the proliferative phase of the menstrual cycle or in a postmenopausal woman. During the secretory phase of the menstrual cycle, the presence of endometrial hyperplasia is likely to be missed sonographically, because hyperplastic endometrium and normal secretory endometrium have similar sonographic appearances.

In a postmenopausal woman not on hormone replacement therapy, a sonogram to assess for endometrial hyperplasia can be performed at any time. In a postmenopausal woman on sequential hormone replacement therapy, the findings of endometrial hyperplasia can best be seen shortly after progesterone withdrawal bleeding, when the endometrium is expected to be at its thinnest.

When ultrasound demonstrates diffuse thickening of the endometrium, endometrial hyperplasia should be included in the differential diagnosis, along with endometrial polyps and carcinoma. SIS and color Doppler can provide additional diagnostic information. The SIS finding that is characteristic of endometrial hyperplasia is a saline-filled uterine cavity surrounded in its entirety by diffusely thick endometrial tissue (Figures 30.2.1 and 30.2.3), which rules out a focal lesion such as a polyp. Color Doppler of endometrium hyperplasia typically shows flow within the endometrium but no single feeding vessel (Figure 30.2.2), helping differentiate it from a polyp. A definitive diagnosis of endometrial hyperplasia, however, can only be made by tissue sampling (office biopsy or dilation and curettage).