The New Revision from the ACOG on Endometrial Biopsies

When a woman experiences abnormal uterine bleeding, one of the most common diagnostic procedures recommended is an endometrial biopsy. While this test has been used for decades and can provide valuable information, many patients are unaware of its limitations, potential discomfort, and the newer technologies that may offer a more complete evaluation of the uterine cavity as a first means of diagnosis.

What Is an Endometrial Biopsy?

An endometrial biopsy is a procedure in which a physician removes a small sample of tissue from the lining of the uterus, known as the endometrium. The tissue is then examined under a microscope to look for abnormalities such as precancerous changes, endometrial cancer, hormonal effects on the uterine lining, or other causes of abnormal bleeding.

The widespread use of office-based endometrial biopsy began in the early 1990s after studies suggested that the procedure could accurately detect many cases of endometrial disease. As a result, small disposable biopsy devices became common in gynecologic practices and were adopted as a routine part of evaluating abnormal bleeding.

Prior to the introduction of these office biopsy devices, many women underwent a procedure known as dilation and curettage (D&C), which required dilation of the cervix and surgical removal of tissue from the uterine lining, often under anesthesia. While D&C remains useful in certain situations, less invasive office procedures gradually became the preferred first step for many physicians.

Understanding the Limitations of a Blind Biopsy

One important consideration is that a traditional endometrial biopsy is considered a “blind” procedure. The physician cannot directly visualize the inside of the uterus during tissue collection. Instead, a small instrument is inserted through the cervix and a limited amount of tissue is sampled from portions of the uterine lining.

In many cases this approach provides useful information. However, because only a relatively small amount of tissue is collected, there is the possibility that localized abnormalities may not be included in the sample.

This limitation has prompted many gynecologists and imaging specialists to advocate for diagnostic approaches that allow direct visualization of the uterine cavity whenever appropriate.

My Main Issue with these Endometrial Biopsies

The new revision of the American College of Obstetricians and Gynecologists calls for endometrial sampling, no matter what the transvaginal ultrasound lining shows, in a huge number of women who bleed during the menopause. I have had a problem with such sampling for many years. Even the American College of Obstetricians and Gynecologists tends to use the words “sampling” and “biopsy” interchangeably.

So, I took the opportunity to look up the definitions of both. The National Cancer Institute defined biopsy as, “taking a piece of tissue for pathologic analysis. This includes needle biopsy, incisional biopsy, and excisional biopsy.” “Sampling” implies taking a portion of something that will be representative of the entire sample. An analogy would be taking some water out of a reservoir to analyze it with the assumption that this is indicative of the entire body of water. The so called, “biopsy of the uterus” takes a small piece with the assumption that this represents the entire uterine cavity.

Studies have shown that when a cancer occupies less than 50% of the surface area of the uterine lining such blind endometrial sampling can be fraught with error. Although the very first study done on 40 women with cancer who had blind sampling in clinic the week before their hysterectomy, they claimed cancer was obtained in 39, yielding an accuracy rate of 97.5%. This had very wide publicity and resulted in a rapid change in the standard of care to utilize such techniques in patients who might have uterine cancers.

In a subsequent study of 65 women with known cancer where they had such blind endometrial sampling done in the operating room just before the initiation of their hysterectomy, 16.5% of the cancers were missed with such blind biopsy samples! That investigator, however, then opened up the uteri and found that in all the cancers that were missed, less than 50% of the surface area was involved. In other words, such tumors are not always global and can be missed. Other investigators have found miss rates of 17%, 33%, and another 33% in patients with known cancers who underwent such biopsy sampling procedures prior to their hysterectomy.

The reliability of such endometrial sampling is much lower than the reliability of a well performed, distinct ultrasound evaluation of the endometrial lining. Yet in this new revision of the ACOG document, although they now advise such individual sampling, there is no commentary or analysis of the potential shortcomings of such sampling. I have objected strenuously to that. But to no avail.

Practitioners and patients both need to understand these shortcomings. Hopefully, well informed practitioners will understand this and, in spite of the guidance from the ACOG, not subject all of such patients to invasive endometrial sampling and take it even further when such sampling is unsuccessful.

Dr Steven R. Goldstein is a leading Gynecologist in NYC in private practice for over 35 years. A tenured Professor of Obstetrics and Gynecology at New York University School of Medicine, Dr Goldstein’s ground breaking research in the field, especially on Transvaginal Ultrasounds has literally changed the way gynecology is practiced. Much of his research has become the standard of care with the ACOG.

If you are suffering from any bleeding or been told you need to have an endometrial biopsy by your gynecologist, then schedule a consultation with Dr Steven R. Goldstein, a top NYC Gyn for a second opinion.