Imaging Modalities for the Non-Invasive Diagnosis of Endometriosis

Summary

A Cochrane review [Abstract] 1 included 49 studies with a total of 4807 subjects: 13 studies evaluated pelvic endometriosis, 10 endometriomas and 15 deeply infiltrating endometriosis, and 33 studies addressed endometriosis at specific anatomical sites. The most studied modalities were transvaginal ultrasound (TVUS) and magnetic resonance imaging (MRI). Predetermined criteria for a clinically useful imaging test to replace diagnostic surgery included sensitivity at least 94% and specificity at least79%. Criteria for triage tests were set at sensitivity at least 95% and specificity at least 50%, ruling out the diagnosis with a negative result (SnNout test - if sensitivity is high, a negative test rules out pathology) or at sensitivity at least 50% with specificity at least 95%, ruling in the diagnosis with a positive result (SpPin test - if specificity is high, a positive test rules in pathology).

No imaging test met the criteria for a replacement or triage test for detecting pelvic endometriosis, albeit TVUS approached the criteria for a SpPin triage test. For endometrioma, TVUS (sensitivity 0.93, 95% CI 0.87 to 0.99 and specificity 0.96, 95% CI 0.92 to 0.99; 8 trials, n=765) qualified as a SpPin triage test and approached the criteria for a replacement and SnNout triage test, whereas MRI (sensitivity 0.95, 95% CI 0.90 to 1.00 and specificity 0.91, 95% CI 0.86 to 0.97; 3 trials, n=179) met the criteria for a replacement and SnNout triage test and approached the criteria for a SpPin test.

For deep endometriosis, TVUS (sensitivity 0.79, 95% CI 0.69 to 0.89 and specificity 0.94, 95% CI 0.88 to 1.00; 9 trials, 12 data sets, n=934) approached the criteria for a SpPin triage test, and MRI (sensitivity 0.94, 95% CI 0.90 to 0.97 and specificity 0.77, 95% CI 0.44 to 1.00; 6 studies, 7 data sets, n=266) approached the criteria for a replacement and SnNout triage test. TVUS met the criteria for a SpPin triage test in mapping deep endometriosis to uterosacral ligaments, rectovaginal septum, vaginal wall, fossaf Douglas and rectosigmoid. MRI met the criteria for a SpPin triage test for fossa Douglas and vaginal and rectosigmoid endometriosis. Other imaging tests assessed in small individual studies could not be statistically evaluated.

A meta-analysis 2 included 30 studies with 4 565 participants with deep infiltrating endometriosis. Physical examination had a pooled sensitivity of 71% and a specificity of 69%, with an average diagnostic accuracy [area under the curve (AUC) =0.76]. TVUS had a pooled sensitivity of 76% and a specificity of 94%, with higher diagnostic accuracy than physical examination (AUC =0.92). Transrectal ultrasound (TRUS) had a pooled sensitivity of 91% and a specificity of 80% with an AUC of 0.93. MRI had a pooled sensitivity of 82% and a specificity of 87% with higher diagnostic accuracy than physical examination (AUC =0.91).