Postmenopausal AUB: Rule out endometrial cancer first
When a postmenopausal woman presents with abnormal uterine bleeding, endometrial cancer is the biggest concern. But a host of other etiologies also are possible. The author reviews them and outlines a systematic approach to diagnosis.
Anatomic problems. Bleeding that persists after 6 months of continuous combined HRT often is related to an anatomic problem in the uterus, such as a uterine polyp, or a submucous fibroid or adenomyoma impinging on the endometrial cavity. Endometrial hyperplasia also could be to blame, although this is unlikely when progestins are used continuously—unless the condition was preexisting. The addition of progestin to the HRT regimen reduces the risk of endometrial cancer in postmenopausal women to less than that experienced by women not taking HRT, though only if it is used continuously, rather than cyclically or sporadically. In fact, the use of cyclic progestin for less than 10 days a month has been associated with an increased risk of endometrial cancer after 5 years, compared with regimens in which progestin is taken more frequently.11
Perimenopausalwomen placed on HRT during an episode of ovarian resistance may later experience erratic bleeding.
Hormonal factors. Other causes of post-menopausal bleeding in women taking HRT often relate to hormonal factors, such as those that occur when an HRT patch does not adhere properly or is not replaced as directed, or when the patient fails to take her medications correctly.12 This is becoming less common, however, now that some HRT preparations contain the estrogen and progestin components in 1 pill. In addition, the packaging of some preparations is now similar to that of OCs, with punch cards listing the days of the week, making it easier to tell if the appropriate pill has been taken.
On rare occasions, other medications may interfere with the absorption of HRT or increase its hepatic metabolism. This will result in lower levels of available estrogen and, consequently, atrophic bleeding. It is therefore helpful to obtain an estradiol level for women taking HRT preparations. In addition, endometrial atrophy should be apparent on the TVUS of the endometrium (endometrial stripe less than or equal to 4 mm) or from the endometrial biopsy. Occasionally, the endometrium’s response to the progestin is insufficient to obtain a secretory endometrium. These women will have a proliferative histology on endometrial biopsy, and should achieveces-sation of bleeding with an increase in the progestin dose.
Once menopause has occurred, uterine bleeding in the absence of exogenous HRT should be considered abnormal.
Sometimes perimenopausal women are placed on HRT during an episode of ovarian resistance, based on the assumption that they are menopausal. These patients may later experience erratic bleeding once their ovarian function returns, since the dose of estrogen in HRT is insufficient to suppress ovarian function. Low-dose OCs may offer these women better control of uterine bleeding and menopausal symptoms.13 Once menopause—defined by the absence of menstruation for 1 year—has occurred, uterine bleeding in the absence of exogenous HRT should be considered abnormal.
Conclusion
Because endometrial cancer is present in 1 of 8 postmenopausal women who present with AUB, ruling out this malignancy should be the first step in evaluation. Fortunately, since AUB is one the first harbingers, endomtrial cancer usually can be detected early in its course. Among the modalities useful in evaluating postmenopausal bleeding are TVUS, endometrial biopsy, saline-infusion sonohys-terography, and hysteroscopy with directed biopsy. The circumstances and characteristics of the individual patient help determine the best route of exploration and treatment.
Dr. Eisenberg reports that she serves on the Speakers Bureau at Pfizer.
