Postmenopausal bleeding (PMB) is a frequent medical problem that accounts for approximately 5% of all gynaecological consultations. In 10% of women with PMB, endometrial cancer is the underlying cause, which makes endometrial cancer the most common malignancy of the female genital tract in developed countries. Adoption of transvaginal ultrasound (TVS) measurement of endometrial thickness as the first line diagnostic test in PMB algorithms has minimised the need for more invasive endometrial evaluation with endometrial sampling and hysteroscopy. However, the endometrial thickness cutoff to exclude endometrial cancer and the need for further testing remains the subject of debate. Four systematic reviews and meta-analyses have been published on this subject with differing conclusions. Some of these meta-analyses suffer from the fact that authors of smaller studies titrated an optimal cut-off, thereby maximising the specificity for a sensitivity of almost 100%, whereas others suffer from partial verification bias because the need for endometrial biopsy was conditional upon the endometrial thickness measurement by TVS.
The study by Wong et al. published in this issue of the journal is unique because it describes the largest cohort of women presenting with PMB where invasive assessment of the endometrium has been done in all women independent from the results of the preceding TVS endometrial thickness measurement. Indeed, the optimal threshold that combines an almost perfect sensitivity with an acceptable specificity appears to be 3 mm. At this cut-off point, positive and negative predictive values were 6.5 and 0.26%. Higher cut-off values, e.g. 5 mm, would result in positive predictive values of over 10% but a negative predictive value of 0.35%. Awareness of these trade-offs can inform decision making. The prevalence of endometrial cancer among women with PMB in this cohort from Hong Kong was 3.7%, which is much lower than the previously assumed 10%. Whether this is due to the large unselected population or due to differences in the incidence of endometrial cancer in an Asian population is unclear and requires further study.
Although strategies for investigating PMB based upon TVS endometrial thickness thresholds are well established, further refinement is possible by integrating patient characteristics and thereby the individual risk of endometrial cancer, into decisions about the need and type of testing required. Other studies have shown that increasing age, older age at menopause, BMI, nulliparity, diabetes and recurrent bleeding increase the risk of endometrial cancer. These data of Wong et al. can help further refine and validate existing prediction models. In this way, pre- and post-test probabilities of endometrial cancer could be maximised, which in turn will reduce the harm done and wasting of resources arising from unnecessary testing.

dx.doi.org/10.1111/1471-0528.13438, hdl.handle.net/1765/90320
BJOG: An International Journal of Obstetrics and Gynaecology
This is a mini commentary on AS-W Wong et al., pp 439–446. To view this article visit http://dx.doi.org/10.1111/1471-0528.13342
Department of Gynaecology & Obstetrics

Breijer, M.C, & Mol, B.W.J. (2016). Transvaginal ultrasound measurement of the endometrium remains the first line test for investigating postmenopausal bleeding but integration of patient characteristics into testing may further improve diagnostic algorithms. BJOG: An International Journal of Obstetrics and Gynaecology (Vol. 123). doi:10.1111/1471-0528.13438