David Shalowitz, MD, MSHP, explains new dual approach for postmenopausal bleeding

At the 2026 American College of Obstetricians & Gynecologists Annual Clinical & Scientific Meeting, David Shalowitz, MD, MSHP, gynecologic oncologist and presenter of the session, “The Latest and Greatest Guidance Updates,” further detailed the rationale behind updated clinical guidance recommending a dual approach to evaluating postmenopausal bleeding, emphasizing evolving evidence that challenges long-standing reliance on transvaginal ultrasound alone.^1,2

Historically, an endometrial thickness of 4 mm or less on ultrasound was considered highly reassuring. “Previously, data suggested that an endometrial thickness of four millimeters or less was associated with greater than a 99% negative predictive value for endometrial cancer, and then said another way, that you could reasonably reassure a patient that if the endometrial thickness was four millimeters or less, it was very, very, very unlikely that that patient had an underlying malignancy,” Shalowitz said.

However, he noted that these estimates are based on outdated and limited data. “Now, those data, unfortunately, are mostly from 20 years ago, and also only 2 studies out of the 40 that were included in a recent meta-analysis were actually conducted in the United States,” he said.

More recent evidence suggests a higher risk of missed diagnoses when ultrasound is used alone.

“Now, more recent data suggest that using a 4 millimeter cutoff for endometrial thickness to triage to endometrial sampling or not may miss 5% to 12% of endometrial cancers, and from our organizational standpoint, and our commitment to ensure that patients who potentially have an underlying cancer get the treatment and diagnosis that they need, that's just too high,” he added.

Refining risk-based evaluation

While the updated guidance broadly recommends combined ultrasound and biopsy², Shalowitz emphasized that a limited subset of low-risk patients may still be candidates for ultrasound-only evaluation.

“So, for the majority of patients, the dual approach is appropriate and recommended. In a select set of very low-risk patients, ultrasound without endometrial biopsy may be reasonable, provided several criteria are met,” he said. “Second, patients must not have any factor that is substantially associated with the development of endometrial cancer, and this includes, but is not limited to, body mass index of greater than 30, comorbid diabetes mellitus, the concomitant use of a selective estrogen receptor modulator like tamoxifen, exogenous hormone use with estrogen, with or without progestin, a family history of a syndrome that may predispose that patient to higher risk of endometrial malignancy, and Black race,” Shalowitz said.

Addressing disparities and diagnostic gaps

A central driver of the updated recommendations is concern about reduced diagnostic accuracy in higher-risk populations.

“The first is, from a statistical standpoint, the likelihood of missing an endometrial cancer in the non-Hispanic Black population is somewhere around 9 to 8-point some percent, which is very high,” Shalowitz said. He further noted that reliance on endometrial thickness alone may be particularly problematic for aggressive cancer subtypes. “Reliance solely on an endometrial thickness of 4 millimeters or less potentially misses up to 25% of those cancers in one modeling study,” he said.

These limitations, combined with rising incidence and mortality, underscore the need for a more proactive approach.

“So the decreased statistical performance that we've seen that comes along with the increase over the last 20 years in prevalence and mortality for people who have endometrial cancer, along with the specific association of these high-risk cancers with non-Hispanic Black patients, shows that reliance on the old guidance overly disadvantages a particularly vulnerable population,” Shalowitz said. “It is absolutely critical that patients are kept informed as to why every test is recommended or performed, the reasons for that recommendation, the risks and benefits associated with procedures, and what the next steps will be depending on what the outcomes are of that testing,” he said.

As clinicians adopt a more proactive biopsy approach, patient engagement remains central.

“However, every test and every intervention that is done needs to be the result of shared decision-making between patients and their clinicians, and it is absolutely critical, again, that people understand why certain recommendations are made and that there has been a change in society-level guidance based on solid data that make us more proactive in recommending tissue sampling, whereas perhaps a year ago, that was not as much the standard,” he said.

References:

1. Fitch J. ACOG updates guidance for evaluating postmenopausal bleeding. Contemporary OB/GYN. Published April 17, 2026. Accessed May 19, 2026. https://www.contemporaryobgyn.net/view/acog-updates-guidance-for-evaluating-postmenopausal-bleeding
2. Shalowitz, D. ACOG: The Latest and Greatest Guidance. Session. Presented at: American College of Obstetricians & Gynecologists Annual Clinical & Scientific Meeting. May 1-3, 2026. Washington, D.C.