Usefulness and limits of CA-125 in diagnosis of endometriosis without associated ovarian endometriomas.

BACKGROUND The aim of this study was to evaluate the diagnostic significance of CA-125 for endometriosis without ovarian endometriomas. METHODS Preoperative serum CA-125 levels were measured in 775 consecutive women diagnosed by laparoscopy or laparotomy with endometriosis, adenomyosis, leiomyomas, or normal pelvis. RESULTS Receiver operating characteristic curve analysis revealed that the area under the curve for endometriosis without endometriomas was 0.788, significantly smaller than that for endometriosis with endometriomas (0.935, P < 0.05). In diagnosis of endometriosis without endometriomas, both the maximal accuracy of 78.8% and the maximal diagnostic value of 61.2% were obtained at the cutoff value of 20 U/mL. Negative predictive value was 78.0% at the cutoff value of 20 U/mL, whereas positive predictive value was 92.9% at the cutoff value of 30 U/mL. This range is clearly superior to the empirical single cutoff of 35 U/mL. CONCLUSIONS In the diagnosis of endometriosis without endometriomas, combined use of two cutoff values for CA-125, 20 and 30 U/mL, provides improved diagnostic performance. However, the accuracy of using only CA-125 testing for diagnosis is still limited. Serum CA-125 testing can be done during initial screenings of women with possible endometriosis.