Endometriosis Diagnostics

Laboratory Tests and Ancillaries

Urinalysis and urine culture are used to identify pain originating in the urinary tract (eg cystitis, stones). Pregnancy tests and tests for sexually transmitted infections (STIs) like gonorrhea and chlamydia, when appropriate, are also utilized.

Laparoscopy

Laparoscopy is the gold standard for diagnosis unless lesions are visible in the vagina. It may also be used for therapeutic purposes. It should not be done during or within three months of hormonal treatment to avoid underdiagnosis.

Biopsy and histopathologic study of at least one lesion is ideal. The three cardinal features (ie ectopic endometrial glands, ectopic endometrial stroma, hemorrhage into adjacent tissue) should be present. In adolescents, the features of endometriosis may be atypical (ie clear vesicles, red lesions).

A negative laparoscopy does not exclude the diagnosis of endometriosis. Depending on the severity of the disease found, it is best to remove the endometriotic lesion at the same time. Differential diagnoses can be excluded by biopsy. 

Laparoscopic Classifications

The Revised American Society for Reproductive Medicine (rASRM) Score (formerly the Revised American Fertility Society [rAFS] Score), which is based on the location, extent and severity of lesions, noted aspects including bilaterality, depth of invasion, size, involvement of the ovary and cul-de-sac, and density of adhesions. It does not take into account the retroperitoneal structures and deep infiltrating endometriosis. Scoring is as follows:

• 1-5 for minimal disease (stage I)
• 6-15 for mild disease (stage II)
• 16-40 for moderate disease (stage III)
• >40 for severe disease (stage IV)

The Enzian Staging System takes into account the presence of deep infiltrating endometriosis. It supplements the rASRM score with a description of deep infiltrating endometriosis, retroperitoneal structures, and other organ involvement.

Serum CA-125

Women with endometriosis may have high serum CA-125 concentrations. It has no value as a diagnostic tool in endometriosis, though it may be used to assess the presence of an undiagnosed adnexal mass. It is also elevated in ovarian epithelial neoplasia, myoma, adenomyosis, acute pelvic inflammatory disease (PID), ovarian cyst, and pregnancy.

Biopsy

A biopsy may be considered in suspected endometriosis lesions and endometriomas to help confirm the diagnosis and exclude possible malignancy. It is recommended for the diagnosis of patients with mild to moderate endometriosis. In patients with endometriosis, the prevalence of ovarian cancer is <1%.

Imaging

Transvaginal Sonography (TVS)

Transvaginal sonography is considered the first-line imaging tool to examine suspected endometriosis. It should be performed to determine whether a pelvic mass or structural anomaly is present. It is useful in diagnosing or excluding rectal endometriosis.

It may identify an ovarian endometrioma and help identify other structural causes of pelvic pain, such as ovarian cysts, torsion, tumors, genital tract anomalies, and appendicitis. It also distinguishes endometrioma from other ovarian cysts with 83% sensitivity and 89% specificity. Ovarian endometrioma may be diagnosed in premenopausal women with findings of ground glass echogenicity, one to four compartments, and the absence of papillary structures with blood flow.

Magnetic Resonance Imaging (MRI)

MRI may be helpful in some cases to better define an abnormality suspected by sonography. It detects ovarian endometrial cysts with 90% sensitivity and 98% specificity. It provides the exact location of the deep retroperitoneal lesion and is useful in ruling out other pelvic organ involvement such as bowel or bladder. It may be used as part of a pre-operative workup but should not be used as first-line.

Computed Tomography (CT) Scan

CT scan may show the size and different characteristics and densities of adnexal masses. It is used to evaluate other pathology or organ involvement. Chest CT is useful for thoracic endometriosis.

Other Imaging Studies

Cystoscopy, colonoscopy, and rectal ultrasonography may be required if deep endometriosis is suspected.