From the Guidelines
The normal endometrial stripe thickness is less than 5 mm in postmenopausal women and varies with the phase of the menstrual cycle in premenopausal women, with no validated absolute upper limit cutoff. When evaluating the endometrial stripe, it's essential to consider the patient's age and menstrual cycle phase. In postmenopausal women, an endometrial thickness of 4 mm or less conveys a negative predictive value for cancer of nearly 100% 1. For premenopausal women, the endometrial thickness varies with the phase of the menstrual cycle, and many studies have shown that the thickness of the endometrium is not an indicator of endometrial pathology 1. Key points to consider when evaluating the endometrial stripe include:
- The standard method for measuring endometrial thickness is transvaginal ultrasound 1
- Abnormal echogenicity and texture of the endometrium have been correlated with significant underlying uterine pathology 1
- An endometrial thickness of 5 mm or more in postmenopausal women generally prompts evaluation by endometrial tissue sampling 1
- In premenopausal women, even if the endometrial thickness is less than 5 mm, endometrial polyps or other endometrial pathology may be present 1
From the Research
Normal Endometrial Stripe Thickness
- The normal endometrial stripe thickness can vary depending on the individual and the phase of the menstrual cycle 2.
- A study published in 2004 found that an endometrial stripe thickness of less than 5 mm in premenopausal women did not exclude the presence of endometrial polyps or submucosal fibroids 3.
- Another study published in 2023 found that there is no consensus on the endometrial thickness cut-off for recommending endometrial biopsy in asymptomatic postmenopausal women 4.
- A study published in 2019 reported a mean endometrial thickness of 4.5±3.7 mm in females aged 0-20 years, with significant association with age 2.
- The American College of Obstetricians and Gynecologists (ACOG) does not provide a specific cut-off value for normal endometrial stripe thickness, but recommends that any abnormal uterine bleeding be evaluated with endometrial biopsy or imaging 5.
Factors Affecting Endometrial Stripe Thickness
- Age: Endometrial stripe thickness increases with age 2.
- Menstrual cycle phase: Endometrial stripe thickness varies throughout the menstrual cycle, with thicker measurements typically seen during the luteal phase 2.
- Hormonal influences: Unopposed estrogen exposure can lead to increased endometrial stripe thickness 6, 5.