In UK, a definite diagnosis of endometriosis is made around twelve years after the onset of symptoms due to overlapping symptoms of other gynaecological conditions (1).
- laparoscopic visualisation is considered the gold standard investigation, unless visible lesions are seen in the posterior vaginal fornix or elsewhere (1,2,3)
- changes suggestive of endometriosis may sometimes be seen on ultrasound scan
- NICE state:
- offer a transvaginal ultrasound scan to all women or people with suspected endometriosis, even if pelvic or abdominal examination is normal, to:
- identify ovarian endometriomas and deep endometriosis, including that involving the bowel, bladder or ureter
- identify or rule out other pathology which may be causing symptoms
- guide management options and enable referral to an appropriate service, depending on the ultrasound findings
- if a transvaginal scan is not appropriate, consider a transabdominal ultrasound scan of the pelvis
- do not exclude the possibility of endometriosis if the abdominal or pelvic examination and ultrasound scan are normal, and recognise that referral may still be necessary even with a normal scan
- consider specialist transvaginal ultrasound scan or pelvic MRI scan to diagnose deep endometriosis and assess its extent
- ultrasound (1):
- transvaginal ultrasonography (TVS)
- helpful in assessing endometriotic ovarian cysts.
- TVS is of little value in assessing the presence of adhesions and mild peritoneal deposits
- TVS may be useful in assessing deep infiltrating disease, where endometriosis involves the Pouch of Douglas
- often hypoechoic linear thickening, or nodules/masses with or without regular contours can be seen on TVS
- endoanal ultrasound
- has been evaluated for the diagnosis of deep infiltrating endometriosis
- during a diagnostic laparoscopy, consider taking a biopsy of suspected endometriosis (3):
- to confirm the diagnosis of endometriosis (be aware that a negative histological result does not exclude endometriosis)
- to exclude malignancy if an endometrioma is treated but not excised
- consider laparoscopy to diagnose endometriosis in women or people with suspected endometriosis, even if the ultrasound scan or MRI scan was normal
- investigation of other possible sites is dictated by symptoms e.g. cystoscopy if bladder involvment is suspected
Do not exclude the possibility of endometriosis if the abdominal or pelvic examination, ultrasound or MRI are normal. If clinical suspicion remains or symptoms persist, consider referral for further assessment and investigation (3)
Notes (3):
- Serum CA125
- do not use serum CA125 to diagnose endometriosis
- if a coincidentally reported serum CA125 level is available, be aware that:
- a raised serum CA125 (that is, 35 IU/ml or more) may be consistent with having endometriosis
- endometriosis may be present despite a normal serum CA125 (less than 35 IU/ml)
- MRI
- do not use pelvic MRI as the primary investigation to diagnose endometriosis in women with symptoms or signs suggestive of endometriosis
- consider pelvic MRI to assess the extent of deep endometriosis involving the bowel, bladder or ureter
- ensure that pelvic MRI scans are interpreted by a healthcare professional with specialist expertise in gynaecological imaging
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