NAMS Notes: An expert approach to common menopause-related problems

Key Points

The following questions and answers summarize cases discussed in Menopause e-Consult, a newsletter of The North American Menopause Society (NAMS). (For a full description of each case, refer to the original issue of each e-newsletter.)

TO BIOPSY, OR NOT?

A 57-year-old woman who is 6 years postmenopausal reports blood in her underwear. She believes it is from the vagina. The only medication she is taking is a bisphosphonate. Examination reveals atrophic vaginal changes but no source for the bleeding. Transvaginal ultrasound (TVS) shows a thin distinct endometrial echo measuring 2.8 mm, no adnexal masses, and no free fluid. Is endometrial biopsy necessary?¹

IN THIS CASE, I believe that blind endometrial sampling will not provide additional information. Two questions are relevant: What evidence is there for the reliability of blind suction piston biopsy? How reliable a finding is the thin distinct endometrial echo observed in this patient with transvaginal ultrasound?

Although a 1991 study of the disposable biopsy device, Pipelle, found a sensitivity of 97.5%,² subsequent studies of prehysterectomy Pipelle sampling showed positive results in only 68% to 92% of patients with known carcinoma-that is, the technique missed malignancies 8% to 32% of the time.

IN ANOTHER STUDY of 65 women with known carcinoma, prehysterectomy Pipelle sampling failed to identify 17% (11) of the cancers.³ Moreover, blind biopsy tended to overlook smaller cancers. Three of the missed tumors occupied less than 5% of the endometrial surface, four less than 25%, and four less than 50%. The authors concluded that Pipelle sampling is effective (100% sensitivity) if the tumor is larger than 50% of the endometrium. A previous study demonstrating that the Pipelle device sampled an average of 4% of the surface of the uterus corroborated this conclusion.⁴ Clinicians who perform endometrial biopsy need to keep these limitations in mind.

How reliable is TVS for excluding endometrial cancer? Early studies comparing ultrasound with endometrial biopsy consistently found that an endometrial echo 4 to 5 mm or less reliably ruled out endometrial cancer.⁵ Subsequent large multicenter trials ranging in size from 97 to 394 women found that cancer occurred in 0% to 0.6% of women with a thin distinct echo.

MUCH LARGER MULTICENTER TRIALS showed TVS to have a high negative predictive value. A Nordic trial found no cancers on curettage among 1,168 postmenopausal women who had an echo of 4 mm or less.⁶ An Italian study of 930 women revealed only two malignancies in women with an echo of 4 mm or less-a 99.79% negative predictive value-and four cancers in women with an echo of 5 mm or less-a 99.57% negative predictive value.⁷

Because of its high negative predictive value, TVS is a reliable initial examination for the postmenopausal patient with bleeding. Women with a thin distinct echo 4 to 5 mm or less (negative predictive value greater than 99%) do not need endometrial biopsy.

Ultrasound has some limitations, however. Conditions such as axial uterus, marked obesity, fibroids, and previous uterine surgery can make it difficult to obtain reliable results. An alternative method of examination-such as saline infusion sonohysterography or hysteroscopy-is indicated when ultrasound does not detect a thin distinct endometrial echo.

DISCLOSURE: Dr. Goldstein reports: Cook Ob/Gyn and Akrad Labs, A Cooper Company (consultant); Phillips Ultrasound (equipment loan); and Sonosite (director).

REFERENCES

1. North American Menopause Society. Menopause e-Consult. April 2007;3(2):3-5, http://www.menopause.org/econsult.html.