Preoperative ultrasound diagnosis of deep endometriosis: importance of the examiner's expertise and lesion size

Objectives: To evaluate the accuracy of transvaginal sonography (TVS) in the diagnosis of deep infiltrating endometriosis (DIE) of the posterior compartment (rectovaginal septum, uterosacral ligaments, rectosigmoid colon, vagina) when undertaken by physicians of varying experience and to investigate if size of the nodule is relevant in influencing diagnostic accuracy. Methods: 381 patients who were operated on between January 2007 and December 2010 for suspected pelvic endometriosis were prospectively recruited. Clinical, surgical and histopathologic data were collected and a preoperative TVS was carried out. Comparison was made between the diagnostic accuracy of TVS performed by two groups of physicians of different expertise. Results: One hundred and thirty-six patients underwent removal of deep endometriotic lesions of the posterior compartment. Sensitivity, specificity, positive and negative predictive value and the overall diagnostic accuracy of the expert operators were 77%, 95%, 90%, 87% and 88% respectively. Corresponding values for first-level operators were: 45%, 98%, 92%, 79% and 81%. In patients with positive findings at TVS, the mean diameter of the endometriotic nodule was of 4.7 ± 3.4 cm while, in cases with negative findings, the average diameter was 2.6 ± 1.1 cm (P < 0.05). Conclusions: TVS is accurate in detecting the presence of DIE. Accuracy is dependent on the experience of the physician and the size of the nodule.