How Endometrial Cancer Is Diagnosed

While most women begin the process of being diagnosed with endometrial cancer as a result of visiting their doctor for abnormal vaginal bleeding or discharge, for some women, the diagnostic process begins as a result of an abnormality detected during a routine pelvic examination.

Whatever starts the process, it's important to keep in mind that an endometrial biopsy (when a tissue sample is removed from the inner lining of the uterus) is the gold standard test for diagnosing endometrial cancer. That said, other tests like a thorough medical history and blood and imaging tests certainly aid in the diagnostic process.

endometrial cancer diagnosis
Illustration by Verywell

Medical History

Let's say a woman comes in with abnormal vaginal bleeding. In order for a gynecologist (a doctor who specializes in treating the female reproductive system) to pinpoint a diagnosis, including a possibility for endometrial cancer, she will start by asking several questions about the bleeding.

Some of these questions may include:

  • How long has the bleeding gone on for?
  • How much are you bleeding?
  • Are there any symptoms associated with the bleeding? (for example, pain, fever, or an odor)
  • Does the bleeding occur after sex?
  • What medications are you taking?
  • Do you have a family or personal history of bleeding problems?
  • Are you experiencing any new vaginal discharge, even if non-bloody?

This last question is pertinent because while the vast majority of endometrial cancers cause abnormal vaginal bleeding (if any symptoms are present), about 10 percent of women experience a non-bloody vaginal discharge as their only symptom.

After reviewing a woman's medical history, a gynecologist will perform a physical examination, including a pelvic exam, to confirm that the bleeding is coming from the uterus and not from other organs (for example, the vulva, cervix, anus, or rectum).

Labs and Tests

In addition to a medical history and physical examination, various tests may be performed, mostly to rule out non-uterine problems. For instance, since the cervix connects the uterus to the vagina, a pap smear may be performed. During a pap smear, a cell sample is taken from the cervix to screen for cervical cancer. Likewise, if a woman is noting vaginal discharge or odor, a cervical swab may be performed to check for infection.

Blood Tests

There is no single blood test that can diagnose endometrial cancer. However, many doctors will order a complete blood count (CBC) to check for anemia (low red blood cell count), which may be caused by endometrial cancer, among other health conditions. Other blood tests your doctor may order to evaluate for whole-body causes of bleeding include:

  • Blood clotting tests
  • Thyroid function panel
  • Complete metabolic panel (CMP) to check for liver or kidney disease
  • Pregnancy test

Imaging and Biopsy

An ultrasound (a machine that uses sound waves to take images of the body) is the first test used to evaluate a woman's reproductive organs, including her uterus, ovaries, and fallopian tubes. Your doctor may start with a pelvic ultrasound, in which the ultrasound probe is placed (along with warm gel) on the lower abdomen or pelvis. Then he will move forward with a transvaginal ultrasound, which is a more optimal test for visualizing the uterus and determining whether or not endometrial cancer is present.

Transvaginal Ultrasound

With a transvaginal ultrasound, the ultrasound probe is placed inside the vagina where it is closer to the uterus. During the transvaginal ultrasound, the lining of the uterus is examined and measured. In addition, certain endometrial abnormalities, like polyps or tumors, can be visualized

Saline Infusion Sonohysterography

A saline infusion sonohysterography entails a gynecologist performing a transvaginal ultrasound after filling the uterus with saline (salt water). Compared to a transvaginal ultrasound, this test allows for better visualization of the uterus, so smaller and more obscure abnormalities may be detected.

While an ultrasound is a helpful tool, the only way to diagnose endometrial cancer is through a biopsy.

Endometrial Biopsy and Hysteroscopy

An endometrial biopsy means that a small tissue sample of the uterus is removed by the gynecologist during a procedure called a hysteroscopy, which is a procedure usually performed in a doctor's office using local anesthesia. During a hysteroscopy, a tiny scope is placed into the uterus through the vagina and cervix. A small amount of tissue is then removed by a special suction instrument.

This tissue sample is then examined under a microscope by a specialized doctor called a pathologist. The pathologist looks at the tissue to see whether there are cancerous cells present. Sometimes, an endometrial biopsy is not sufficient, meaning not enough tissue was gathered, or the biopsy results are unclear (the pathologist can not definitively say whether cancer cells are present). In this case, a procedure called a dilation and curettage (D&C) will be performed.

Dilation and Curettage (D&C)

A D&C is a more complicated procedure that cannot be done in the doctor's office, but rather in an outpatient surgical center, as it requires general anesthesia or sedation (in addition to local anesthesia or an epidural to numb the lower part of the body). During a D&C, the cervix is dilated, and a thin instrument (called a curette) is used to scrape away tissue from the inner lining of the uterus. A D&C can be done with or without the use of a hysteroscope.

Staging

Once endometrial cancer is diagnosed, a specialized cancer doctor (called a gynecologic oncologist) will stage the cancer, which means she will determine how far the cancer has spread. The tests used to stage endometrial cancer often include:

  • Chest x-ray
  • Computed tomography (CT) scan
  • Magnetic resonance imaging (MRI) test

The stages of endometrial cancer are:

  • Stage 1: Cancer has not spread outside the body of the uterus
  • Stage 2: Cancer has spread from the body of the uterus into the cervical stroma (tissue that connects the uterus to the cervix)
  • Stage 3: Cancer has spread to the outer surface of the uterus or outside of the uterus to the pelvic lymph nodes, fallopian tubes, ovaries, or vagina
  • Stage 4: Cancer has spread to the rectum, bladder, groin lymph nodes, abdomen, or distant organs like the lungs, liver, or bones

Differential Diagnosis

It's important to understand there are many potential non-cancerous conditions that can cause abnormal bleeding from the uterus; however, the only way to be certain that cancer is (or is not) present is through a biopsy, which is why a visit to your gynecologist is essential.

Other possible causes of abnormal uterine bleeding that your doctor will consider, include:

  • Excessive thinning of the vaginal and uterine lining (due to low estrogen levels in menopause)
  • Uterine polyps or fibroids
  • Infection of the uterus
  • Medications like blood thinners

Of course, keep in mind that what you may think is vaginal bleeding may, in fact, be bleeding from a different location, such as your bladder or rectum. This is why a thorough medical history and physical examination is important to start—so only necessary tests (like an endometrial biopsy) are performed.

Premenopausal Women

While endometrial cancer is most common in postmenopausal women, it's important to note that it can occur in young women, even adolescents (albeit rarely). This is why in certain instances (for example if a woman is 45 years or older or has risk factors for endometrial cancer (regardless of her age), she will still need to be ruled out for cancer with an endometrial biopsy.

In terms of a differential diagnosis of abnormal uterine bleeding in premenopausal women, a doctor will consider some of the following conditions: 

  • Polycystic ovarian syndrome or other problems related to ovulation
  • Pregnancy
  • Problems linked to birth control pills or an intrauterine device
  • Fibroids and polyps
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