The finding of asymptomatic endometrial thickening on ultrasound presents a clinical management dilemma and is a frequent reason for referral by family physicians. Endometrial thickness is measured as the maximum anterior–posterior thickness of the endometrial echo on a long-axis transvaginal view of the uterus. Concern is raised when an endometrium of > 5 mm is discovered during an ultrasound examination, often one that is undertaken for non-gynaecologic reasons. Subsequent radiologic reports prompt interventions that can be invasive and involve risk. The incidence of endometrial thickening ( ≥ 4.5 mm) in postmenopausal women ranges from 3% to 17%, while the incidence of endometrial cancer in an unselected postmenopausal population is 1.3 to 1.7/1000.
- The American Cancer Society does not recommend routine screening of asymptomatic patients for endometrial cancer.
- The Canadian Cancer Society reports that there is inadequate evidence that screening by ultrasonography or endometrial sampling would reduce the mortality from endometrial cancer.
- The 2001 consensus statement on bleeding published by the Society of Radiologists in Ultrasound included a caveat that the 5 mm threshold does not apply to asymptomatic women with incidentally observed thickened endometrium.
- In 2009 (reaffirmed 2015), the American College of Obstetricians and Gynecologists stated that there was no evidence to recommend routine investigations for asymptomatic endometrial thickening (greater than 4 mm).
Despite this recommendation, clinicians are concerned when the ultrasound report states that endometrial cancer cannot be ruled out because of endometrial thickening found in an asymptomatic postmenopausal woman. Goldstein, in 2010, recommended postmenopausal asymptomatic endometrial thickening be evaluated on a case-by-case basis. The clinician must consider risk factors for endometrial cancer including obesity, polycystic ovary syndrome, and diabetes mellitus in their decision making. Goldstein emphasized that it is inappropriate to investigate every asymptomatic patient with thickened endometrium > 5 mm.
Asymptomatic endometrial thickening found on ultrasound examination in postmenopausal women often poses a clinical management dilemma. Although the prevalence of endometrial cancer is relatively low in women with no bleeding, the disease has the best outcome when it is found at an early stage. The disease is usually diagnosed at an early stage when postmenopausal women present with bleeding. Routine ultrasound screening for asymptomatic women is not recommended. Current evidence suggests that certain subsets of women at high risk of developing endometrial cancer who have endometrial thickening on ultrasound and other positive findings (increased vascularity, inhomogeneity of endometrium, particulate fluid, excessively thickened endometrium > 11 mm) should be referred to gynaecologists for further investigations. Women with risk factors for endometrial cancer and endometrial thickening such as tamoxifen use, obesity, hypertension, and late menopause should be triaged on an individual basis. Polyps found in asymptomatic postmenopausal women need not be removed routinely. However, factors such as polyp size and histopathology, and patient age must be incorporated into the decision for polypectomy. Investigations for asymptomatic endometrial thickening are not risk free, and serious complications such as bowel injury and uterine perforation have been reported in the literature. Thus, adoption of these recommendations may reduce anxiety, pain and risk of procedural complication to the postmenopausal patient.
Following are the recommendations by SOGC Clinical Practice Guideline “Asymptomatic endometrial thickening” (2010):
- Transvaginal ultrasound should not be used as screening for endometrial cancer. (II-1E)
- Endometrial sampling in a postmenopausal woman without bleeding should not be routinely performed. (II-1E)
- Indications for tissue sampling of the endometrium in bleeding postmenopausal women with an endometrial thickness of greater than 4 to 5 mm should not be extrapolated to asymptomatic women. (II-2E)
- A woman who has endometrial thickening and other positive findings on ultrasound, such as increased vascularity, inhomogeneity of endometrium, particulate fluid, or thickened endometrium over 11 mm, should be referred to a gynaecologist for further investigations. (II-1A)
- Decisions about further investigations should be made on a case-by-case basis in asymptomatic women with increased endometrial thickening and risk factors for endometrial cancer such as obesity, hypertension, and late menopause. (II-1B)
- In asymptomatic women on tamoxifen, a routine ultrasound for endometrial thickening should not be performed. (II-2E)
- Not all postmenopausal women who have asymptomatic endometrial polyps require surgery. Women found to have asymptomatic polyps on ultrasound should be triaged for intervention according to size of the polyp, age, and other risk factors. (II-1A)
Whereas several studies have evaluated transvaginal ultrasonography in postmenopausal women with bleeding, there are fewer data on transvaginal ultrasonography endometrial findings in patients without bleeding. In 1,750 postmenopausal women without bleeding being screened for a selective estrogen receptor modulator study, an endometrial thickness of less than or equal to 6 mm had a negative predictive value of 99.94% for excluding malignancy (only 1 case of cancer in 1,750 women) and a 99.77% negative predictive value for complex hyperplasia (only 4 cases in 1,750 women). Among 42 patients with endometrial thickness of greater than 6 mm, there was 1 case of adenocarcinoma and no cases of hyperplasia (positive predictive value = 2.4%).
In another study, 82 asymptomatic postmenopausal women had an incidental ultrasonographic finding suspected to be an intrauterine polyp. All underwent operative hysteroscopy. Of these patients, a benign polyp was found in 68, submucosal myoma in 7, atrophic endometrium in 6, and proliferative endometrium in 1. One polyp contained simple hyperplasia. There were no cases of endometrial carcinoma or complex hyperplasia. The total complication rate was 3.6% (two perforations, one difficult intubation).
The significance of an endometrial measurement greater than 4 mm incidentally discovered in a postmenopausal patient without bleeding has not been established. This finding need not routinely trigger evaluation, although an individualized assessment based on patient characteristics and risk factors is appropriate. Transvaginal ultrasonography is not an appropriate screening tool for cancer in postmenopausal women without bleeding.
ACOG Committee Opinion (reaffirmed 2015) recommends the following;
“The significance of an endometrial thickness of greater than 4 mm in an asymptomatic, postmenopausal patient has not been established, and this finding need not routinely trigger evaluation.”