Imaging the endometrium: disease and normal variants.

The endometrium demonstrates a wide spectrum of normal and pathologic appearances throughout menarche as well as during the prepubertal and postmenopausal years and the first trimester of pregnancy. Disease entities include hydrocolpos, hydrometrocolpos, and ovarian cysts in pediatric patients; gestational trophoblastic disease during pregnancy; endometritis and retained products of conception in the postpartum period; and bleeding caused by polyps, submucosal fibroids, endometrial hyperplasia, or endometrial adenocarcinoma. Other findings include tamoxifen-associated changes, intrauterine fluid collections, and endometrial adhesions. Although ultrasound (US) is almost always the first modality used in the radiologic work-up of endometrial disease, findings at sonohysterography, hysterosalpingography, magnetic resonance imaging, and computed tomography are often correlated with US findings. It is important to understand that the appearance of the endometrium is related to multiple factors, including the patient's age, stage in the menstrual cycle, and pregnancy status and whether she has undergone hormonal replacement therapy or tamoxifen therapy. Accurate diagnosis requires that these factors be taken into account in addition to clinical history and physical examination findings.