From the Guidelines
After menopause, a normal endometrial thickness is typically considered to be less than 5 mm, as an endometrial thickness of 4 mm conveys a negative predictive value for cancer of nearly 100% 1. When evaluating postmenopausal women, it's crucial to consider the threshold of 5 mm for endometrial thickness, as measurements above this may indicate potential issues such as endometrial hyperplasia or cancer.
- Key points to consider in the assessment of endometrial thickness include: + The use of transvaginal ultrasound (TVUS) as the first-line screening test for endometrial cancer in postmenopausal women with bleeding 1. + The importance of combining TVUS with transabdominal US for a comprehensive assessment of pelvic structures. + The understanding that while TVUS is sensitive for evaluating endometrial thickness, it cannot reliably determine the etiology of endometrial thickening, thus necessitating further evaluation like endometrial tissue sampling for thickened endometrium (≥5 mm) 1.
- In clinical practice, an endometrial thickness of less than 5 mm is generally considered normal in postmenopausal women, and any measurement at or above 5 mm should prompt further investigation, such as endometrial biopsy or hysteroscopy, especially in the presence of postmenopausal bleeding 1.
From the Research
Normal Endometrial Thickness After Menopause
The normal endometrial thickness after menopause can vary, but several studies provide insight into this topic.
- A study from 1997 2 found that in postmenopausal women, an endometrial thickness of less than 4 mm is generally considered normal.
- Another study from 2002 3 measured the endometrial thickness in an asymptomatic postmenopausal population and found that the mean thickness varied with the length of time since menopause, with a mean thickness of 2.3 mm during the first 5 years after menopause and 1.8 mm from 5 to 13 years after menopause.
- A 1991 study 4 investigated the effect of hormone replacement on endometrial thickness and found that an endometrial thickness greater than 0.8 cm may be clinically significant, depending on the patient's hormonal status.
Diagnostic Thresholds
Several studies have explored diagnostic thresholds for endometrial lesions in postmenopausal women.
- A 2016 study 5 found that about 10% of gynecologically asymptomatic postmenopausal women have a sonographic endometrial thickness of 5 mm or greater, and the authors suggest conservative management for these women.
- A 2025 study 6 identified a diagnostic threshold of 5.65 mm for screening endometrial pathology by endometrial thickness in asymptomatic postmenopausal women, with an area under the curve of 0.679 for identifying endometrial lesions.
- The 1997 study 2 used a cutoff point of 4 mm for postmenopausal women, considering an ultrasound examination negative if the single-layer thickness was less than 4 mm in the absence of endometrial projections.
Risk Factors
Some studies have identified risk factors for endometrial thickening in postmenopausal women.
- The 2025 study 6 found that overweight (BMI ≥ 25 kg/m²) is a risk factor for asymptomatic endometrial thickening after menopause, with an odds ratio of 1.132 (P < 0.05, 95% CI 1.039-1.234).
- The same study also found that an endometrial thickness of 4 mm or greater is a risk factor for postmenopausal asymptomatic women, with an odds ratio of 7.927 (P < 0.05, 95% CI 3.015-20.839).