Background: Endometriosis and possible rectal involvement are difficult to assess by physical examination. Previous studies have shown the diagnostic value of magnetic resonance imaging and rectal endoscopic sonography (RES) in this setting, but not that of transvaginal sonography (TVS). The aims of this study were to compare the accuracy of TVS and RES for the diagnosis of pelvic endometriosis, and to compare the results with histological findings.
Patients and methods: In a prospective study, 30 consecutive patients referred with clinical signs of endometriosis underwent TVS and RES; the images were interpreted blindly with regard to physical findings.
Results: Endometriosis was confirmed histologically in 28 (93%) of the 30 patients. Endometriomas were also present in 67% of cases. For the diagnosis of uterosacral endometriosis, the sensitivity, specificity, and positive and negative predictive values of TVS and RES were 75 and 75%, 83 and 67, 95 and 90%, and 45 and 40% respectively. For the diagnosis of rectosigmoid endometriosis, the sensitivity, specificity, and positive and negative predictive values of TVS and RES were 95 and 82%, 100 and 88%, 100 and 95%, and 89 and 64% respectively.
Conclusion: Despite the large proportion of our patients who had intestinal endometriosis, representing a possible source of bias, our results suggest that TVS is as efficient as RES for detecting posterior pelvic endometriosis and should therefore be used as the first-line examination.