Endometriosis is a condition in which tissue similar to the lining of the uterus grows outside of the uterus. Medical professionals sometimes refer to these growths as endometrial growths or lesions.

Pelvic magnetic resonance imaging (MRI) is one imaging technique that doctors may use to help diagnose endometriosis. The test provides a picture of organs inside the pelvic cavity and shows endometrial growths that may require further investigation.

This article discusses getting a pelvic MRI, what it may show, and what to expect. It also describes other tools doctors use to diagnose endometriosis.

A woman wearing a hospital gown prepares for an MRI.Share on Pinterest
simonkr/Getty Images

An MRI is a type of imaging technique that uses magnets and radio waves to create individual images or “slices” of areas in the body. A technician stores the slices on a computer or prints them onto film.

The first-line imaging method for diagnosing endometriosis is a pelvic ultrasound. The second-line imaging method is a pelvic MRI. Both tests can reveal abnormalities, but neither can definitively diagnose endometriosis, since the abnormalities may be the result of other causes.

Medical professionals classify the severity of endometriosis according to the location, depth, extent, and severity of endometrial growths. Preoperative staging enables practitioners to plan therapy and offer a prognosis. A pelvic MRI is the best imaging technique for preoperative staging of endometriosis. Compared with an ultrasound, it provides a more reliable picture of deep, infiltrating lesions that require further investigation.

Below is information about the different types of pelvic MRIs, what they show, how to prepare, and what to expect.

Types

A person having a pelvic MRI may have a traditional closed type, which involves lying on a narrow table that slides into an MRI machine. If a person has a fear of enclosed spaces, a doctor may order an open type, which is less enclosed.

What they show

Pelvic MRIs show endometrial growths on structures within the pelvis. This includes sex organs, such as the ovaries, vagina, and fallopian tubes. It also includes organs and tissues not connected to the reproductive system, such as the bladder and colon.

The following are some signs of endometriosis that a pelvic MRI may reveal:

  • Peritoneal implants: These are growths along the wall of the abdomen.
  • Adhesions: These are bands of dense connective tissue that may appear to tether pelvic structures.
  • Urinary tract lesions: These lesions affect up to 20% of people with endometriosis. Lesions on the bladder can cause thickening of the bladder wall, which is identifiable on an MRI.
  • Endometriomas: These masses are large collections of blood and fluid.

Additionally, a pelvic MRI may show changes to the anatomical position of pelvic structures due to endometrial growths. These may include:

  • kissing ovaries, which refers to ovaries touching each other or in close proximity to each other
  • displacement of the uterus deeper into the pelvic cavity
  • elevation of part of the vagina
  • abnormal bends, curves, or loops in the bowel
  • thickening of ligaments, muscles, or tendons within the pelvis

How to prepare

A person should take the following steps when preparing for a pelvic MRI:

  • Inform the doctor about any health conditions: This includes any allergies, recent surgeries, or metal implants.
  • Let the doctor know about claustrophobia: If a person is afraid of enclosed spaces, their doctor may prescribe a medication to induce relaxation, or they may suggest an open MRI.
  • Follow the doctor’s instructions regarding preparing for an MRI: This may include avoiding eating or drinking anything for several hours before the test.
  • Remove metal objects: Because MRIs contain strong magnets, a person will need to remove any metal objects before entering the examination room. Examples include:
    • jewelry
    • belts
    • wristwatches
    • hearing aids
    • pens

What to expect

Before a person enters the examination room, hospital staff will ask them to remove any metal items, such as metal jewelry or clothing. They may ask the person to wear a hospital gown that does not have metal fasteners.

Once inside the examination room, the person will lie on their back on a table in front of the MRI machine. A technician will ask the person to wear ear defenders, which help cancel out the noise of the MRI machine.

The technician will place small devices around the hip area to send and receive radio waves. In some cases, a person may receive an intravenous dye before the test begins. The dye helps the technician identify internal body structures and tissues.

When the person and technician are ready, the table will slide into the center of the ring-shaped MRI machine. The technician will leave to enter an adjoining room. An intercom allows the person and technician to communicate during the MRI.

An MRI scan is not painful and typically takes around 30–50 minutes.

Other tools for diagnosing endometriosis include ultrasound and laparoscopy.

Ultrasound

An ultrasound is the first-line imaging technique for diagnosing endometriosis. Like an MRI, it uses sound waves to produce a picture of a person’s internal organs. The procedure involves inserting a wand-shaped scanner into the vagina or moving a scanner across the abdomen.

Laparoscopy

Surgery is the only way doctors are able to confirm a suspected case of endometriosis. The most common surgical procedure is a laparoscopy, although a diagnosis of endometriosis does not always require one.

A laparoscopy involves inserting a device called a laparoscope through a small incision in the abdomen. A laparoscope is a thin tube with a camera attached. The camera allows a surgeon to look for signs of endometriosis inside the pelvis.

If a surgeon identifies areas of abnormal tissue, they can insert small surgical instruments into the abdomen to take a tissue biopsy. A lab technician will later view the sample under a microscope to confirm the diagnosis.

A pelvic MRI is the second-line imaging method doctors may use to aid in the diagnosis of endometrial growths inside the pelvis. The results may suggest that endometriosis is present, but a laparoscopy will be necessary to confirm the diagnosis.

A person should follow their doctor’s instructions regarding how to prepare for an MRI. A technician will be available to talk the person through the procedure on the day.

An MRI test is not painful and usually lasts from 30–50 minutes. During this time, a person can communicate with their technician via an intercom.