The Value of Pelvic MRI in the Diagnosis of Posterior Cul-De-Sac Obliteration in Cases of Deep Pelvic Endometriosis

OBJECTIVE. The objective of our study was to define relevant MRI signs allowing preoperative diagnosis of posterior cul-de-sac obliteration in patients with deep pelvic endometriosis. MATERIALS AND METHODS. This retrospective study included patients who underwent pelvic MRI completed by a laparoscopic examination. Three radiologists performed the MRI review blinded and recorded the following signs: sign 1, retroflexed uterus; sign 2, retrouterine mass; sign 3, displacement of intraperitoneal fluid; sign 4, elevation of the fornix; and sign 5, adherence of bowel loops. Laparoscopic results provided the criterion standard for diagnosis of posterior cul-de-sac obliteration. The performance of MRI was evaluated by calculating the average sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of MRI results of the two more experienced radiologists for each sign and for combinations of signs. Interobserver agreement for each sign and impression for posterior cul-de-sac obliteration were calculated for all radiologists. RESULTS. Sixty-three patients were included in the study. Posterior cul-de-sac obliteration was diagnosed in 43 patients at laparoscopy. The mean sensitivity, specificity, and accuracy of each sign and impression of posterior cul-de-sac obliteration were, respectively, as follows: sign 1, 24.4%, 77.5%, 41.3%; sign 2, 97.1%, 83.7%, 92.8%; sign 3, 95.0%, 88.7%, 93.1%; sign 4, 30.2%, 97.5%, 51.6%; sign 5, 83.7%, 91.2%, 86.1%; and impression of posterior cul-de-sac obliteration, 91.9%, 91.2%, 91.7%. Interobserver concordance varied from 0.26 to 0.81 with best results obtained with the combination of signs 2, 3, and 5. Best concordances for junior radiologist evaluations were obtained with assessment of sign 3. CONCLUSION. MRI allows posterior cul-de-sac obliteration diagnosis. Pelvic fluid displacement may be the sign with greatest utility when considering both diagnostic accuracy and interobserver agreement.