Endometriosis tends to develop slowly, so it often takes years to receive a firm diagnosis after the first time a patient reports her symptoms. Healthcare practitioners typically suspect this condition after taking a health history and physical examination. Surgery remains the gold standard for diagnosing endometriosis, although some noninvasive techniques also have clinical value.


Healthcare practitioners typically refer to the signs of endometriosis as lesions, although they also may call them implants or nodules. Endometriotic lesions typically appear as dark blue or black areas that look like powder burns. However, they can also be other colors such as white, yellow, red, and brown, depending on the stage and severity of the lesion. Lesions typically appear on pelvic organs or intra-abdominal areas first, but larger lesions, also medically known as endometriomas are most common within the ovaries. These lesions usually have a brownish appearance due to the presence of old blood and are commonly known as chocolate cysts.


Laparoscopy is the most common surgery for diagnosing endometriosis. This procedure involves the insertion of a thin cable with the camera on the end into the abdominal cavity, which is currently the only way to visualize the extent and severity of internal lesions caused by endometriosis. Practitioners may also be able to diagnose endometriosis by direct observation in cases where the signs are visible externally, typically nodules in the vagina.

A biopsy may be taken during the laparoscopy at this time, but it’s more common to simply proceed with surgical treatment. About 6 to 13 percent of patients have no visible signs of endometriosis, requiring a biopsy to diagnose the condition. This can occur even when the patient is experiencing chronic pain, which can also be caused by other pelvic conditions such as adenomyosis, masses in the ovaries or fallopian tubes, pelvic adhesions and pelvic inflammatory disease.


Small lesions require direct observation to diagnose endometriosis, but vaginal ultrasound may be able to identify large endometriomas. This procedure involves extending the probe into the anterior and posterior pelvic compartments. The sonographer will then look for deep nodules, noting their size and location. This procedure is most likely to have clinical value when the lesions located deep within the pelvic walls. It’s also useful for monitoring the spread of this condition in cases where clinical suspicion of endometriosis is already well-established.

Ultrasound offers many advantages over surgery, including its lower-cost, accessibility, and lack of contraindications. The primary challenge in using ultrasound is that it requires an experienced technician to properly interpret the images. Presently, this technique is primarily used to manage endometriosis and enhance the patient’s quality of life. However, ultrasound techniques are improving rapidly, which will reduce the number of laparoscopies that practitioners must perform to diagnose endometriosis.


The American Society of Reproductive Medicine (ASRM) most recently revised the stages of endometriosis in 1997. This system uses a complex point system to assign one of four stages to the physical disease and does not address symptoms such as pain or infertility. This point is important to note as a patient with Stage I endometriosis may be in severe pain, while a patient in stage IV endometriosis may experience no pain. This often occurs because the tissue becomes less sensitive as scarring increases.

For more information, please visit our complete Endometriosis Guide.