Although endometriosis sometimes shows up on an ultrasound, it doesn’t always. If a doctor thinks you have endometriosis, laparoscopic surgery is the only way to definitively diagnose it.

Endometriosis is a gynecological condition in which cells similar to the uterine lining grow in areas outside of the uterus.

Traditionally, surgery has been the gold standard for confirming a diagnosis of endometriosis. But this doesn’t mean endometriosis is only detectable through surgery.

In some cases, imaging tests like ultrasound and MRI can identify endometriosis growths. An ultrasound is usually part of the early diagnostic process.

Read on to learn more about how ultrasounds are used when diagnosing endometriosis.

Sometimes, but not always. If the endometriosis growths are large enough, they can show up on an ultrasound. Identifying it this way allows doctors to make a preliminary diagnosis.

But a comprehensive diagnosis is more than just an imaging test. In endometriosis, a comprehensive diagnosis means establishing the location, size, and depth of lesions, as well as assessing the involvement of surrounding organs and the presence of scar tissue.

One key reason why diagnosing endometriosis using ultrasound is challenging is because it can be hard to differentiate between endometriosis lesions and other structures.

Ultrasound, also called sonography, uses sound waves to create images of internal structures. Once these sound waves are sent into the body, they’re reflected back by your tissues, creating a real-time image or video that depicts the size, shape, texture, and density of organs and their structures.

Modern ultrasounds can create detailed imaging, but they can be limited when it comes to infiltrating deeper tissues and cavities or differentiating between structures with similar density. This can make confirming endometriosis over other gynecological conditions tricky. It means that deeper, smaller lesions may go undetected.

According to a 2016 review, no diagnostic imaging methods were accurate enough to provide a comprehensive diagnosis of overall pelvic endometriosis. But ultrasound was considered an accurate way for surgeons to create targeted operative procedures.

Ultrasound for endometriosis is done transabdominally (on the outside of the abdomen) and transvaginally (through the vaginal canal).

There isn’t much preparation for the procedure, and you can go home as soon as it’s done. You may be asked to take a bowel preparation the night before to help clear your system for better image clarity.

At the time of the ultrasound, you’ll be asked to empty your bladder and undress from the waist down, covering your bottom half with a gown or sheet. Lying down on your back, your legs are positioned apart and bent at the knees.

The technician will use a handheld device coated with ultrasound gel to gently press against your abdomen. If you need an internal ultrasound, they’ll use a probe that’s inserted into your vagina.

It’s natural to feel a sensation of pressure on your abdomen or when as the transducer is inserted into the vaginal canal. The gel might feel cool, although many facilities warm it for comfort.

To perform the ultrasound, the transducer is slowly turned and pressed against your skin at different angles.

Using this approach, doctors evaluate your uterus, fallopian tubes, ovaries, kidneys, bladder, and related structures. They’re assessed for abnormalities, tenderness, and how freely they move within the abdomen and in relation to one another.

There are currently no laboratory tests available that diagnose endometriosis.

According to a 2023 diagnostic criteria proposal, the reason for this is that there are no reliable biomarkers to diagnose endometriosis.

Biomarkers are measurable indicators of a disease, like levels of proteins, levels of enzymes, levels of hormones, or structural changes, which are detectable through testing. Basically, the lack of biomarkers for endometriosis means that there isn’t a blood test that can identify it.

Visual confirmation remains the only way to confirm the presence of endometrial lesions and related scarring.

In addition to ultrasound and surgery, MRI is a visual tool that can identify endometriosis. But it’s still limited in what it can show, and it can also be more time consuming and expensive.

Even though an ultrasound is considered a noninvasive medical procedure with very few negative risks, discussing the procedure with a doctor beforehand can help you understand why it’s being performed and what to expect.

Questions to consider asking a doctor include:

  • Who’s going to perform the ultrasound?
  • Will the ultrasound be both transabdominal and transvaginal?
  • Will you need to have multiple visits and ultrasounds?
  • Can you have a loved one there for support?
  • What preparation is necessary the night before?
  • Are there any changes to current medications before the ultrasound?
  • What specific information is the ultrasound going to provide?
  • How long will the ultrasound take?
  • Based on your individual symptoms, what level of discomfort is expected?
  • Are there any risks?
  • Should you expect any changes or side effects after the ultrasound?
  • Can you undergo the procedure if you’re pregnant, having your period, or experiencing abnormal uterine bleeding?
  • How soon do the results come back?

Experts can see endometriosis on diagnostic imaging tests, such as an ultrasound, but surgery is still necessary to make a comprehensive diagnosis.

Ultrasound offers a way to verify the location and presence of endometriosis, but it may not be able to identify small lesions or those deeper within the abdomen.

Distinguishing endometriosis from other similarly presenting conditions using ultrasound alone can be challenging. Currently, it’s used as a primary diagnostic tool.