Reproducibility of assessment of severity of pelvic endometriosis using transvaginal ultrasound

Objective To examine the reproducibility of assessment of severity of pelvic endometriosis by transvaginal sonography (TVS). Methods This was a prospective observational study conducted from August 2006 to July 2009 in two academic departments of obstetrics and gynecology. Women with clinically suspected or proven pelvic endometriosis were invited to join the study. All patients included underwent TVS performed by two observers and a laparoscopic assessment of pelvic endometriosis. The ultrasound observers were blinded to each other's results. The reproducibility of TVS was examined by evaluation of interobserver agreement for the American Society of Reproductive Medicine (ASRM) score by BlandAltman analysis and the stage and the diagnosis of deeply infiltrating endometriosis (DIE) by calculation of kappa coefficients. Agreement between the findings on TVS for each observer and those on laparoscopy was also evaluated. Results Thirty-four patients were recruited to the study, and TVS was performed by two ultrasound observers. Of these patients, one did not undergo laparoscopy and was therefore excluded from the final analysis. No endometriosis was found in 12 (36.4%) patients. One patient (3%) had minimal disease, one (3%) had mild disease, five (15.2%) had moderate disease and 14 (42.4%) had severe disease. Interobserver agreement was very good for disease classification on TVS (Cohen's kappa, 0.931). Agreement between TVS and laparoscopy findings was also very good (Cohen's kappa, 0.955 and 0.966 for the two examiners). For ASRM score on TVS, the interobserver 95% limits of agreement were 16.6 to 12.7, with a mean difference of 1.9 (95% CI, 4.35 to 0.71). Conclusion TVS is a reproducible method for assessment of the severity of pelvic endometriosis and shows good agreement with findings on laparoscopy.