The American College of Obstetricians & Gynecologists (ACOG) updated its guidance in April 2026, recommending that most patients with postmenopausal bleeding undergo both transvaginal ultrasonography and an endometrial biopsy. This change follows rising rates of uterine cancer and aims to correct diagnostic gaps, particularly for Black women, where ultrasound alone has shown higher false-negative rates.
How has the ACOG diagnostic protocol changed?
Under previous guidelines, clinicians often used transvaginal ultrasonography as the sole initial tool for patients with postmenopausal bleeding, provided the endometrial thickness measured 4 mm or less. The new ACOG policy shifts this approach by calling for a combination of both ultrasound and endometrial biopsy for most patients during assessment.
Dr. Amy Park, Section Head of Urogynecology & Reconstructive Pelvic Surgery at Cleveland Clinic, says the move is a response to increasing disease incidence and mortality. While ultrasound helps identify other issues like polyps or fibroids, it may not be sufficient on its own to rule out malignancy.
An ultrasound measuring an endometrial thickness of 4 mm or less has a false negative probability of approximately 10% in Black women experiencing postmenopausal bleeding.
Why are endometrial cancer rates rising?
Uterine cancer is one of the few cancer types seeing an upward trend in both incidence and mortality. According to American Cancer Society estimates cited by ACOG, more than 69,000 uterine cancer cases were diagnosed in 2025, resulting in nearly 14,000 deaths.
Dr. Roberto Vargas, a gynecologic oncologist, identifies two primary drivers for this trend:
- Increased obesity rates: Dr. Vargas notes that most endometrial cancers are linked to estrogen. Obesity is associated with increased estrogen levels, which can remain unchecked after ovulation ceases. He calls obesity the most significant modifiable risk factor.
- Uterine retention: As medical treatments for conditions like pelvic pain, fibroids, and abnormal uterine bleeding improve, more women are opting to retain their uteri rather than undergoing hysterectomies.
Dr. Vargas clarifies that these medical advances should not be abandoned, but they do necessitate better identification of high-risk patients before cancer develops.
What role does race play in diagnostic accuracy?
The rise in endometrial cancer disproportionately affects non-Hispanic Black women. Dr. Park reports that endometrial cancer rates are increasing by 1% to 2% annually, but the incidence for Black women is rising by nearly 3% per year, compared to 0.7% for white women. Additionally, the risk of death from the disease is twice as high for Black women.
A major concern involves high-grade histological subtypes, which are often not traditionally linked to estrogen. These aggressive cancers are more common in Black women. Dr. Park warns that if tissue sampling is omitted based solely on a 4 mm ultrasound measurement, about 25% of cases of serous endometrial cancer—a rare and aggressive subtype—may be missed in this population.
Clinicians monitor several factors strongly associated with endometrial cancer, including:
- BMI higher than 30
- Diabetes
- History of hormone therapy or tamoxifen use
- Nulliparity (never having given birth)
- Genetic predisposition
What are the future trends in endometrial cancer treatment?
While mortality rates have not significantly improved over the last 30 years, new research is targeting more effective interventions. Dr. Vargas notes that antibody-drug conjugates—a form of targeted chemotherapy—are currently in clinical trials. However, he expects it will take several years before these treatments impact population-level mortality trends.
In the immediate term, the updated ACOG recommendation is expected to be the most effective way to change outcomes. By shifting toward earlier and more thorough diagnosis, doctors hope to catch cancers before they reach advanced, untreatable stages.
Frequently Asked Questions
When should a biopsy be omitted according to the new guidelines?
According to Dr. Park, a biopsy may be omitted only if a patient has had a single episode of postmenopausal bleeding, a fully visualized endometrium measuring 4 mm or less, and no strong risk factors for malignancy. Even then, the patient must have access to prompt follow-up care.
Is ultrasound still useful if a biopsy is required?
Yes. Dr. Park explains that transvaginal ultrasound is used to evaluate for other pathologies, such as fibroids or polyps, that may be present alongside or instead of cancer.
Why is obesity linked to uterine cancer?
Dr. Vargas states that most endometrial cancers are linked to estrogen. Obesity is associated with increased estrogen levels, which can drive cancer growth in postmenopausal years.
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