Answers

Short answers

1 Transvaginal ultrasound scan of the uterus.

View larger version (58K): [in this window] [in a new window] [PowerPoint Slide for Teaching]   Fig 1 Transvaginal ultrasound shows endometrial thickening measuring 1 cm.

2 Endometrial thickening measuring 1 cm. An acceptable postmenopausal endometrial thickness should be less than 5 mm.

3 Benign endometrial polyps, endometrial hyperplasia, endometrial cancer.

4 The patient requires referral to a cancer centre or unit for full gynaecological evaluation and endometrial sampling to establish the nature of the endometrial thickening.

Long answer
1 Investigations
Postmenopausal bleeding represents 5% of all gynaecology outpatient attendances.¹ Transvaginal ultrasound is a highly reliable first line imaging modality for detecting endometrial abnormalities.

2 Abnormalities
In patients with postmenopausal bleeding, if the endometrial thickness is uniformly less than 5 mm, the probability of endometrial cancer is less than 1%.² The most widely used guidelines available for the management of postmenopausal bleeding are those of the Scottish Intercollegiate Guideline Network (SIGN) and the Department of Health’s Improving Outcomes in Gynaecological Cancer (IOGC).^{3 4} Both guidelines state that women with postmenopausal bleeding, both users and non-users of hormone replacement therapy, should be referred to gynaecological assessment services at cancer units due to an increased risk of endometrial cancer. This assessment may be carried out in one stop clinics or on an urgent outpatient basis. Hysteroscopy and hysterosonography provide a more detailed evaluation of the endometrium. Hysteroscopy also has the added benefit of providing tissue sampling of abnormal areas within the endometrium.

3 Further investigations
Transvaginal ultrasound analyses the entire endometrium, and the abnormality seen within the endometrium may be determined to be endometrial polyps, hyperplasia, or carcinoma. Classically, endometrial hyperplasia involves the whole endometrium and results in widening of the endometrium. The endometrial hyperplasia has a cystic, lace-like appearance on ultrasound. Endometrial polyps manifest as focal areas of endometrial thickening, and if there is sufficient fluid in the endometrial cavity the stalk of the polyp can be seen. Endometrial carcinoma may occur in the form of a polyp, within endometrial hyperplasia, or as a heterogeneous endometrial mass with a widened irregular cavity. The histology must be confirmed in all cases as there is a considerable overlap of ultrasound appearances.

4 What the patient needs next
If there is diffuse thickening of the whole endometrium or focal thickening of any part of the endometrium measuring 5 mm or more, the endometrium must be sampled.^{3 4} Deciding the threshold of endometrial thickness is difficult, as too low a limit will result in a large number of negative investigations and too high a limit will result in failure to detect some endometrial cancers. Women with postmenopausal bleeding who were not taking hormone replacement had a risk of endometrial cancer of approximately 7.3% if the endometrium was over 5 mm thick and less than 0.07% if it was 5 mm or less.⁵ In asymptomatic women the risk of cancer is approximately 6.7% if the endometrial thickness is over 11 mm thick and 0.002% if it is less than 11 mm. The same endometrial thickness carries an increased risk of endometrial cancer with increasing age. If the endometrial thickness is over 11 mm the risk of cancer rises from 4.1% at age 50 to 9.3% at age 79.

The SIGN guidelines use 3 mm or 5 mm thresholds based on a meta-analysis of several papers evaluating transvaginal ultrasound.⁴ The threshold of 3 mm is applied in women who have never used hormone replacement, not used it for more than one year, or use continuous combined hormone replacement. For women taking sequential combined hormone replacement therapy the threshold of 5 mm is applied to exclude endometrial cancer, and the endometrial measurements should be made during the first half of the cycle when possible. The IOGC guidelines recommend an endometrial biopsy if the endometrial thickness is over 5 mm.³ With this strategy the risk of endometrial cancer is less than 1% in the first group of patients and less than 0.2% in women using sequential combined hormone replacement. The combination of abnormal vaginal bleeding and an endometrial thickness 5 mm or greater confers a sensitivity of 92% and specificity of 57% for detecting endometrial cancer.⁶

Cite this as: BMJ 2009;338:a2787