Diagnosis of endometriosis

Endometriosis is a chronic inflammatory gynaecological condition caused by hormone-dependent growth of endometrial-like tissue outside the uterus. Deposits grow on the peritoneum and the ovary and may be superficial or infiltrating. Those that invade the myometrium are referred to as adenomyosis.

A diagnosis of endometriosis should be considered in females who are of reproductive age and present with any of these symptoms. In this topic, female is used to mean anyone presumed female at birth.

Endometriosis can develop or progress after menopause, but this is uncommon. In about 30% of individuals with endometriosis, diagnosis only occurs during investigation of infertility. Earlier diagnosis is important to reduce the likelihood of infertility and other complications, such as progression of debilitating pain and a marked reduction in quality of life.

Atypical symptoms such as vague abdominal or urinary symptoms and acyclical pelvic pain make diagnosis challenging, particularly in adolescence. Acyclical pelvic pain can be constant or intermittent, dull, throbbing or sharp and can be exacerbated with physical activity.

Individuals with an affected first-degree relative have a three- to ten-fold increased risk of endometriosis. Other risk factors include early age at menarche, shorter menstrual cycle length, and greater height.

The differential diagnosis of endometriosis includes primary dysmenorrhoea, uterine fibroids, pelvic inflammatory disease, ovarian cysts, ectopic pregnancy, irritable bowel syndrome, appendicitis, diverticulitis, and interstitial cystitis.

Take a thorough history of the duration and severity of symptoms, family history of endometriosis, and reproductive goals to guide treatment options. Encourage the individual to keep a diary of symptoms to help establish if they are cyclical, and to assess impact on quality of life. Perform a thorough abdominal examination to look for masses or abdominal lower quadrant tenderness. Offer a pelvic examination to look for tenderness of the adnexa or uterus or posterior vaginal fornix, pelvic masses, vaginal nodules or fixed pelvic organs. See Examination of the vulva and vagina for advice on reducing distress related to examination.

Ultrasound, ideally performed at a specialist gynaecological service, can aid diagnosis of endometriosis by detecting endometrial deposits on the ovary, peritoneum or pelvic cavity. It may also detect ectopic pregnancy, ovarian torsion, fibroids and ovarian cysts. A transvaginal scan is most accurate, but a transabdominal scan is an alternative if transvaginal ultrasound is not available, or is declined. Normal findings on an ultrasound scan, do not, however, exclude a diagnosis of endometriosis. Deep infiltrating endometriosis (where deposits invade tissues) is particularly challenging to detect and requires specific expertise for diagnosis.

Although diagnostic laparoscopy with histopathological confirmation after biopsy is the gold standard for confirming endometriosis, it is not required in all individuals; see Indications for referral in endometriosis. Start treatment once a presumed clinical diagnosis is made, based on symptoms and examination findings (with or without supportive ultrasound findings).