Abnormally thickened endometrium (differential)

Abnormally thickened endometrium on imaging may occur for a number of reasons which may be categorized based on whether or not they are related to pregnancy. Etiologies may also be classified based on whether the patient is premenopausal or postmenopausal.

Differential diagnosis

Pregnancy-related

• early pregnancy: prior to sac being visualized (<5 weeks of gestation)
• ectopic pregnancy: thickened endometrium and sometimes fluid collection or pseudogestational sac can be associated
• retained products of conception
  • heterogeneously thickened endometrium, with increased vascularity
  • may be fluid collection(s)
  • findings are usually associated with an enlarged uterus
• intrauterine blood clot: heterogeneous endometrium with no vascularity
• molar pregnancy: thickened with multiple small cystic spaces
• recent gestational state (delivery)
  • endometritis

Non-pregnancy related

• endometrial carcinoma: variable appearance
• endometrial hyperplasia: usually uniformly hyperechoic and tends to be diffuse. Can be a differential diagnosis of many conditions i.e. PCOS
• endometrial polyp: usually hyperechoic, often focal, look for vascular stalk
• Tamoxifen-related endometrial changes: variable appearances
• hormone replacement therapy (HRT): in postmenopausal female
• endometritis: prominent hyperechoic endometrium +/- fluid and debris
• submucosal fibroid with degeneration 
• adhesions: irregular echogenic areas with focal thickening
• obstructed outlet
• ovarian tumors associated with endometrial thickening
  • endometrioid carcinoma of the ovary
  • granulosa cell ovarian cancer

Practical points

• endometrial thickness in the secretory phase (days 14-28) may normally be up to 12-16 mm (see: endometrial thickness)
  • non-emergent ultrasounds are optimally evaluated at day 5-10 of the menstrual cycle to reduce the wide variation in endometrial thickness
• the thickest portion of the endometrium should be measured
• if there is fluid in the uterine cavity, it should be excluded from the measurement, which would be the sum of the two sagittal plane thicknesses
• ~10% of endometrial carcinoma occurs in premenopausal women

See also

• endometrial thickness
• abnormally thickened myometrium
• uterine enlargement