Optimal imaging modality for detection of rectosigmoid deep endometriosis: systematic review and meta-analysis

To review the accuracy of different imaging modalities for the detection of rectosigmoid deep endometriosis (DE) in women with clinical suspicion of endometriosis, and to determine the optimal modality.

A search was conducted using PubMed, MEDLINE, Scopus, EMBASE and Google Scholar to identify studies using imaging to evaluate women with suspected DE, published from inception to May 2020. Studies were considered eligible if they were prospective and used any imaging modality to assess preoperatively for the presence of DE in the rectum/rectosigmoid, which was then correlated with the surgical diagnosis as the reference standard. Eligibility was restricted to studies including at least 10 affected and 10 unaffected women. The QUADAS-2 tool was used to assess the quality of the included studies. Mixed-effects diagnostic meta-analysis was used to determine the overall pooled sensitivity and specificity of each imaging modality for rectal/rectosigmoid DE, which were used to calculate the likelihood ratio of a positive (LR+) and negative (LR-) test and diagnostic odds ratio (DOR).

Of the 1979 records identified, 30 studies (3374 women) were included in the analysis. The overall pooled sensitivity and specificity, LR+, LR- and DOR for the detection of rectal/rectosigmoid DE using transvaginal sonography (TVS) were, respectively, 89% (95% CI, 83-92%), 97% (95% CI, 95-98%), 30.8 (95% CI, 17.6-54.1), 0.12 (95% CI, 0.08-0.17) and 264 (95% CI, 113-614). For magnetic resonance imaging (MRI), the respective values were 86% (95% CI, 79-91%), 96% (95% CI, 94-97%), 21.0 (95% CI, 13.4-33.1), 0.15 (95% CI, 0.09-0.23) and 144 (95% CI, 70-297). For computed tomography, the respective values were 93% (95% CI, 84-97%), 95% (95% CI, 81-99%), 20.3 (95% CI, 4.3-94.9), 0.07 (95% CI, 0.03-0.19) and 280 (95% CI, 28-2826). For rectal endoscopic sonography (RES), the respective values were 92% (95% CI, 87-95%), 98% (95% CI, 96-99%), 37.1 (95% CI, 21.1-65.4), 0.08 (95% CI, 0.05-0.14) and 455 (95% CI, 196-1054). There was significant heterogeneity and the studies were considered methodologically poor according to the QUADAS-2 tool.

The sensitivity of TVS for the detection of rectal/rectosigmoid DE seems to be slightly better than that of MRI, although RES was superior to both. The specificity of both TVS and MRI was excellent. As TVS is simpler, faster and more readily available than the other methods, we believe that it should be the first-line diagnostic tool for women with suspected DE. © 2020 International Society of Ultrasound in Obstetrics and Gynecology.