Introduction: Who Should Undergo Diagnostics

If you experience severe pain during your menstrual periods that stops you from doing normal activities, it may be time to seek medical attention. Endometriosis affects an estimated 10% of women of reproductive age worldwide, but many suffer in silence for years before getting answers^[2]. The condition occurs when tissue similar to the lining of your uterus grows outside the uterus, causing inflammation, scarring, and pain that can significantly impact your daily life^[1].

You should consider seeing a doctor if you have very painful menstrual cramps that interfere with your ability to work, study, or maintain relationships. Heavy periods where you need to change pads or tampons every one to two hours, or bleeding between periods, are also warning signs^[4]. Pain during or after sex, chronic pelvic pain that persists even when you’re not menstruating, and discomfort when using the bathroom are additional symptoms that warrant medical evaluation^[3].

Women who are trying to get pregnant without success should also seek diagnostic testing, as endometriosis can cause fertility problems due to scarring and blockage of the fallopian tubes^[3]. Even if you don’t have all these symptoms, or if your pain is mild, it’s still important to talk to your healthcare provider if something doesn’t feel right. Some women with endometriosis experience severe symptoms with only small areas of tissue growth, while others have extensive endometriosis but minimal pain^[3].

Young people in their teenage years can also develop endometriosis, and the prevalence among adolescents with severe period pain that doesn’t respond to medication is estimated at 50% to 75%^[11]. If you have a family history of endometriosis—meaning your mother, grandmother, or sister has the condition—you should be especially vigilant about symptoms and discuss your risk with a healthcare provider^[3].

Classic Diagnostic Methods

Diagnosing endometriosis is often challenging because symptoms can be similar to other conditions such as pelvic inflammatory disease, irritable bowel syndrome, or ovarian cysts^[4]. The diagnostic process typically begins with a thorough conversation with your doctor about your symptoms and medical history. Your healthcare provider will ask detailed questions about your menstrual cycle, including the severity and timing of pain, how heavy your bleeding is, and any associated symptoms^[2].

A physical examination is an important early step in the diagnostic process. During this exam, your doctor may perform an internal vaginal examination to check your pelvic area and abdomen for any abnormalities or tender spots^[4]. While this examination can provide valuable information, it may not reveal endometriosis if the tissue growths are small or located in areas that are difficult to feel.

Blood tests may be ordered to check for anemia, which is a condition where you don’t have enough healthy red blood cells, often caused by heavy menstrual bleeding^[4]. However, there is currently no specific blood test that can definitively diagnose endometriosis. Blood tests are mainly used to rule out other conditions or to assess the impact of heavy bleeding on your overall health.

Ultrasound is often the first imaging test recommended when endometriosis is suspected^[11]. This test uses sound waves to create pictures of the inside of your body. A transvaginal ultrasound, where a small device is gently placed inside the vagina, can provide clearer images of your reproductive organs than an ultrasound done on the outside of your abdomen^[2]. Ultrasound is particularly useful for identifying fluid-filled sacs on the ovaries called endometriomas, sometimes referred to as “chocolate cysts” because of their dark, blood-filled appearance^[5].

When deeper forms of endometriosis are suspected—particularly when the tissue has grown into organs like the bladder or bowel—doctors may recommend a magnetic resonance imaging (MRI) scan^[11]. An MRI uses powerful magnets and radio waves to create detailed images of soft tissues in your body. This test is more expensive and time-consuming than ultrasound, but it provides more detailed information about the location and extent of endometrial tissue growth.

Unfortunately, most superficial endometriosis—which appears as small patches on the surface of organs—cannot be seen clearly on imaging tests^[8]. This is one reason why diagnosis can be so difficult. The tissue growths may be too small or flat to show up on scans, even when they are causing significant pain.

The only definitive way to confirm endometriosis is through a surgical procedure called laparoscopy^[2]. During this procedure, a surgeon makes a small cut in your abdomen and inserts a thin tube with a camera attached, allowing them to look directly at your pelvic organs. If the surgeon sees areas of endometriosis, they can take small samples of tissue (a biopsy) to examine under a microscope, which provides 100% confirmation of the diagnosis^[8]. In many cases, the surgeon can also remove areas of endometriosis during the same procedure, potentially providing relief from symptoms.

However, not every woman with suspected endometriosis needs to have surgery immediately. Many gynecologic organizations now recommend trying empiric therapy—meaning treatment based on symptoms alone, without surgical confirmation—as a first approach^[11]. If medications help control your symptoms, you may be able to avoid surgery altogether. Surgery is typically reserved for cases where medications aren’t working, when a definitive diagnosis is urgently needed, or when a woman is trying to become pregnant and needs tissue removed to improve her chances.

Diagnostics for Clinical Trial Qualification

When women with endometriosis consider participating in clinical trials, they typically need to undergo specific diagnostic tests to confirm they meet the study’s requirements. Clinical trials are research studies that test new treatments or approaches to managing endometriosis, and having standardized ways to identify and measure the disease is crucial for ensuring the study results are reliable and meaningful.

Most clinical trials require participants to have a confirmed diagnosis of endometriosis, which usually means they must have had a laparoscopy with tissue samples examined under a microscope^[5]. This surgical confirmation ensures that researchers are studying people who truly have the condition, rather than those with similar symptoms from other causes. Some studies may accept participants who have had endometriosis confirmed within a certain time frame, such as within the past five years, while others may require more recent confirmation.

Imaging tests like ultrasound or MRI are often used in clinical trials to assess the size and location of endometrial growths before treatment begins and to monitor changes during the study^[2]. These baseline measurements help researchers determine whether a new treatment is working by comparing images taken at different points in the study. For example, if a trial is testing a new medication, doctors might use ultrasound to measure the size of ovarian cysts at the beginning of treatment and then repeat the test after several months to see if the cysts have shrunk.

Pain assessment is another critical component of clinical trial diagnostics. Researchers need objective ways to measure pain levels so they can determine whether a treatment is helping. Many trials use standardized pain scales where participants rate their pain on a numbered scale, such as 0 to 10, with 0 being no pain and 10 being the worst pain imaginable. Participants may be asked to complete pain diaries, recording their daily pain levels and noting when pain interferes with activities like work, exercise, or sleep.

Blood tests may be used in clinical trials to measure hormone levels or to look for markers of inflammation in the body. While there isn’t a specific blood test that can diagnose endometriosis, certain blood markers may help researchers understand how the disease is affecting the body and whether a treatment is reducing inflammation. Researchers are actively working to develop blood tests that could diagnose endometriosis without surgery, but none have been proven reliable enough for routine clinical use yet.

Quality of life assessments are also standard in endometriosis clinical trials. These are questionnaires that ask about how the disease affects various aspects of daily living, including physical functioning, emotional well-being, social relationships, work productivity, and sexual health. By measuring changes in quality of life throughout the study, researchers can determine whether a new treatment not only reduces pain but also helps people live better, more fulfilling lives.

Some clinical trials may include additional specialized tests depending on what is being studied. For trials focusing on fertility, participants might need to have their fallopian tubes evaluated to determine if they are blocked, or they might need blood tests to check hormone levels related to ovulation. Trials studying the effects of endometriosis on the bowel or bladder might require specialized imaging or procedures to examine these organs more closely.

Before enrolling in any clinical trial, potential participants undergo a screening process to ensure they meet all the study’s criteria. This screening typically involves reviewing medical records, performing physical examinations, and conducting the necessary diagnostic tests. The goal is to create groups of participants who are similar in terms of disease severity and other important characteristics, which makes it easier to determine whether differences in outcomes are due to the treatment being tested rather than differences between the people in the study.