Normal Transvaginal Sonography Endometrial Thickness Measurements Associated With Endometrial Cancer in the Symptomatic Postmenopausal Patient

Abstract

Carcinoma of the endometrium is a difficult abnormality to diagnose with sonography alone. In this case, a transvaginal sonogram resulted in unremarkable findings to evaluate a postmenopausal patient with vaginal bleeding. Further testing went on to establish a diagnosis of grade 1 endometroid adenocarcinoma.

The possibility of endometrial cancer in symptomatic postmenopausal patients is typically first investigated with transvaginal sonography. Postmenopausal vaginal bleeding is the most common symptom of endometrial cancer. ¹ This can range from occasional spotting to spotting that becomes more frequent and profuse. The etiology of endometrial cancer is significant for an increased number of endometrial glands replacing normal supporting stroma due to estrogenic stimulation. ²

With transvaginal sonography, careful measurement of the thickness of the endometrium is crucial as this enables the referring clinician to determine if further evaluation of this symptom then requires an endometrial biopsy.

Along with the actual thickness of the endometrium, the uniformity of the endometrial texture and the endometrial contour need to be imaged with diligence. Irregularities seen in the endometrium can also be significant for benign entities such as endometrial hyperplasia, endometrial polyps, and submucosal leiomyomas.

Case Report

A postmenopausal woman in her 60s presented with complaints of “light vaginal bleeding” for a period of seven days. Her history was significant for a cervical polypectomy nine years prior to this event. Family history included her mother who was diagnosed with endometrial cancer at age 62 years. The patient in this case report was not on hormone replacement therapy and never had been.

Transvaginal sonography was performed using a Philips 400CL sonography unit with a 6.5-MHz transvaginal transducer (Philips, Andover, Massachusetts). The scan revealed two lateral fibroids in the uterus. No right ovary was identified; however, no right adnexal masses or abnormalities were seen. The left ovary was small, unremarkable, and mobile with transducer pressure. There was no free fluid in the cul-de-sac and no complaints of pelvic discomfort with the sonogram. The endometrium contained a scant amount of fluid and had a thickness of 2.8 mm. The contour and texture of the endometrium were unremarkable as well, with only a vague suggestion of a subtle inhomogeneous pattern of echogenicity.

The patient was instructed to follow up with the referring clinician should the bleeding continue or become worse. With complaints of continued bleeding, the decision was made to perform an endometrial biopsy. Results of the biopsy were significant for extensive, well-differentiated grade 1 endometroid adenocarcinoma.

The patient was treated surgically with a total hysterectomy as well as bilateral salpingo-oophorectomy. The surgical pathology confirmed the diagnosis of endometroid endometrial adenocarcinoma. The tumor had invaded the inner one-third of the myometrium. Bilateral iliac and lower aortic lymph nodes were benign.

Discussion

Postmenopausal bleeding can be attributed to several disorders, with the most significant of these being endometrial carcinoma. Other considerations would include endometrial polyps and endometrial hyperplasia. Transvaginal sonography is a valuable tool to assess the endometrial lining when this occurs. The referring clinician relies heavily on the exact measurements of the endometrial thickness when determining what following steps to take regarding the care of that patient.

Endometrial cancer usually occurs in women older than age 50, most of whom have had postmenopausal bleeding. These cases of endometrial cancer demonstrate that the neoplasm often causes a greater degree of endometrial thickening than benign etiologies, although hyperplasia can cause a very thick endometrium. ² One may also image a hypoechoic ring around the endometrial cavity in the postmenopausal patient who is not on hormonal treatment. ² Recent literature states that the acceptable endometrial lining thickness in the postmenopausal patient with bleeding should be 5 mm. ¹ However, postmenopausal women without vaginal bleeding have a risk of endometrial cancer of about .002% and 6.7% if they have an endometrial stripe ≤11 mm or >11 mm, respectively. ¹

More recently, it has been reported that a cutoff value of 3 mm has a sensitivity of 98%. Therefore, transvaginal ultrasonography measurement of endometrial thickness in women with postmenopausal bleeding using a cutoff value of 3 mm is still clinically useful, and using such a cutoff value can reliably exclude endometrial carcinoma in women with postmenopausal bleeding. ³ In the presence of postmenopausal bleeding and in the absence of uterine fibroids, it has been suggested that uterine artery and endometrial Doppler are sensitive in the differentiation of significant pathology from endometrial atrophy.^4,5

Conclusion

The case study reminds us as sonographers that there will always be exceptions. There may be significant abnormalities present even when we consider measurements of the endometrial thickness to be well within the normal limits. Extra effort is needed to evaluate the endometrium not only for its thickness but also for any structural abnormality. This would include deviation of the endometrial canal itself, subtle contour irregularities, and inhomogeneous texture. One may also image a hypoechoic ring around the endometrial cavity in the postmenopausal patient who is not on hormonal treatment. ²

The ultimate decision for further treatment lies with the clinician, but it is necessary to evaluate all aspects of the appearance of the endometrium and not simply to focus on the thickness measurement alone when such patients are referred for sonographic examinations.