What Endometriosis Ultrasounds Detect

A transvaginal ultrasound can detect certain types of endometriosis but not superficial forms. No ultrasound can diagnose endometriosis.

Nevertheless, some surgeons who treat endometriosis may recommend ultrasounds to provide further information about the severity of suspected endometriosis or to guide surgical planning.

Endometriosis ultrasounds help providers:

• Look for endometriomas (cysts filled with endometriosis)
• Look for deep infiltrating endometriosis
• Identify anatomical abnormalities
• Look for possible adhesions
• Identify where lesions could be before surgery

In this article, learn more about the benefits and limitations of ultrasounds for endometriosis.

Reliability of Endometriosis Ultrasounds: What Can They Detect? 

Ultrasounds can be a valuable tool in the endometriosis diagnosis process. However, healthcare providers need more than the results of an ultrasound to diagnose endometriosis since ultrasounds do not reliably show all types of endometriosis.

The three phenotypes (physical appearances) of endometriosis are:

• Endometrioma: A cyst filled with endometriosis tissue, usually growing on the ovaries
• Deep infiltrating endometriosis: Lesions that grow 5 millimeters (mm) or deeper
• Superficial endometriosis: Lesions of less than 5 mm deep

Of these three types of endometriosis, an ultrasound can sometimes identify two of them: endometriomas and deep infiltrating endometriosis.

But ultrasounds cannot detect superficial endometriosis. This can be a barrier to diagnosis because superficial endometriosis is the most common type, making up 80% of all endometriosis cases.

Although the term "superficial" may sound less serious than the other types of endometriosis, this form can be equally debilitating. The type or stage of endometriosis usually is not based on the level of symptoms.

How Endometriosis Looks on an Ultrasound 

An ultrasound uses high-frequency sound waves to visually scan inside the body. The images often are grainy and black-and-white.

Identifying endometriosis on an ultrasound can be tricky. There are certain signs of endometriosis that a trained technician or endometriosis specialist may be able to locate.

An ultrasound for endometriosis can detect the following:

• Mass: A mass of any size that has one chamber (uniocular), looks like it is filled with ground glass, and has minimal blood flow may indicate an endometrioma (endometriosis lesion).
• Pelvic organ immobility: Pelvic organs, such as the uterus, bladder, and bowel, seem to be stuck together.
• Immobile ovaries: When probed (poked), the ovaries seem stuck to the pelvic side wall or another ovary.
• Kissing ovaries: Both ovaries are joined together; this is a strong sign of endometriosis.
• Obliterated rectouterine pouch: Anatomically, there is an open space between the uterus and rectum (also called posterior cul-de-sac and pouch of Douglas). If this space is blocked or filled with fluid, it could indicate endometriosis.
• Anatomical distortion: Any unusual anatomy, such as organs pulled out of their normal position, could indicate adhesions from endometriosis.
• Abnormal fallopian tubes: In some cases, the fallopian tubes are moved out of position by endometriosis and appear like long, snakelike cysts on an ultrasound.
• Abnormal tissue thickening: Deep endometriosis may appear as significant thickening of tissue in one area. It may appear as what is referred to as hypoechoic on ultrasound, which means dark gray and solid due to a lack of echoes.

Most ultrasound lab technicians aren't trained to recognize these subtle signs of endometriosis on ultrasounds.

Normal vs. Abnormal Findings 

You may be told that your endometriosis ultrasound is normal or abnormal. In a normal ultrasound, the pelvic organs are mobile and freely move when probed. There are no signs of cysts or masses and no areas of unusual thickening of tissue.

In an abnormal ultrasound, your technician may observe that specific organs seem "stuck" and don't move when probed. This could be a sign of adhesions from endometriosis. They may also notice organs in abnormal locations, masses or cysts, focal areas of thicker tissue, and more.

Types of Endometriosis Ultrasounds

You may only be familiar with ultrasounds in the context of pregnancy, in which a cold gel is applied to the abdomen before a wand is manually moved over it and pressed into it to display a video of what is inside. That type of ultrasound is called an abdominal ultrasound.

Abdominal ultrasounds usually are not used for endometriosis because they don't provide enough detail of the pelvic organs. The most common type of ultrasound for endometriosis is transvaginal, though a transrectal ultrasound may be used in some cases.

Transvaginal

A lubricated probe is gently inserted into the vagina during a transvaginal ultrasound. Some technicians may let you insert the probe yourself to aid in comfort.

Then, the technician will move the probe in a systematic method. As the probe is moved, you may experience some discomfort. It is typically not a painful procedure, but pain is a possibility due to the location and nature of endometriosis. Let your technician know if you are in pain so they can adjust the probe.

You can see the sonogram (ultrasound visuals) displayed on a video screen during the procedure. The technician will take screenshots for a doctor to analyze.

Transrectal

Less frequently, a transrectal ultrasound is performed to investigate endometriosis. This is usually offered if transvaginal ultrasound is painful or not a possibility.

A small, lubricated probe is inserted into the rectum during a transrectal ultrasound. This may feel like having a bowel movement, but it is typically not painful.

"Unremarkable" Endometriosis Ultrasound Results: What to Do Next 

After your ultrasound, you may be told that your "findings are unremarkable." Healthcare providers may use this phrase when they don't find any signs of endometriosis.

Some people may feel distressed upon receiving negative results, especially those who experience symptoms of endometriosis and want answers to explain their pain and other symptoms.

Remember that healthcare providers cannot use ultrasound to diagnose or rule out endometriosis definitively. When certain signs are found, it may indicate the presence of two types of endometriosis. But when no signs are found, it does not rule out the existence of endometriosis.

Your ultrasound results should be used to help plan the following steps, whether that's surgical planning or something else.

Endometriosis Ultrasound and Staging

Endometriosis is staged via the American Society of Reproductive Medicine (ASRM) staging system, which signifies the impact of the disease on fertility but does not correlate to symptoms.

It is not possible to stage endometriosis from an ultrasound alone. For a healthcare provider to diagnose and stage endometriosis, you must undergo excision surgery.

During the procedure, a surgeon will record all instances of superficial endometriosis, deep endometriosis, and endometriomas. Excised samples will be sent to a pathologist to confirm the diagnosis.

Other Endometriosis Diagnostic Testing 

A healthcare provider may recommend other scans to look for signs of endometriosis, such as magnetic resonance imaging (MRI). Similar to ultrasound, healthcare providers use these methods to gather information about the extent of your disease or assist in surgical planning. They are not used to diagnose endometriosis.

Determining the "Right" Testing

You may wonder if an ultrasound for endometriosis is valuable since it cannot diagnose the disease.

Diagnostic tests, including ultrasounds and MRIs, can be costly, averaging $12,118 per patient each year in the United States. Furthermore, getting either a positive or negative ultrasound does not mean a (potentially expensive) endometriosis surgery is not needed.

Many people with suspected endometriosis find that tests that don't provide definitive information contribute to their anxiety and feelings of a lack of validation for their symptoms and lived experience, possibly contributing to the seven- to nine-year diagnostic delay.

However, many endometriosis surgeons recommend ultrasounds because they provide clues to the severity of endometriosis and assist in surgical planning. For example, if your ultrasound reveals a mass in the bowels, your surgeon may plan for a colorectal surgeon to be on call.

Collaborate with a healthcare provider to determine if an ultrasound is right for you.

Summary

Transvaginal and transrectal ultrasounds are valuable tools when investigating possible endometriosis. However, healthcare providers cannot use ultrasound to diagnose endometriosis. Two of the three types of endometriosis (endometriomas and deep infiltrating endometriosis) are visible with ultrasound, while superficial endometriosis, which represents 80% of cases, is not. Ultrasound does not replace excision surgery and pathology as the gold standard for endometriosis diagnosis.