Serum CA-125 in preoperative patients at high risk for endometriosis

Obstet Gynecol. 2002 Mar;99(3):375-80. doi: 10.1016/s0029-7844(01)01731-8.

Abstract

Objective: To investigate the factors contributing to the elevated level of CA-125 in endometriosis and to study whether CA-125 assay is useful to identify women who require preoperative bowel preparation.

Methods: A total of 685 women undergoing surgery for endometriosis between July 1988 and June 1999 were studied. Preoperative serum CA-125 levels were compared between various pelvic conditions using F statistics. Multiple regression was employed to determine significant correlates of elevated serum CA-125, and the receiver operating characteristic curve was applied to assess the utility of serum CA-125 in preoperative preparation. Based on the two-sample Student t test, the sample size required to detect a difference in mean serum CA-125 levels of one-half of one standard deviation with a power of 90% when the sample size ratio of the two groups was 1:50 was 675 with a significance level of 5%.

Results: The mean serum CA-125 levels (IU/mL) for American Society of Reproductive Medicine stages I, II, III, and IV endometriosis were 18.8 +/- 0.9, 40.3 +/- 2.8, 77.1 +/- 3.5, and 182.4 +/- 14.0, respectively. CA-125 levels were significantly increased with advanced stages (P <.001, F test). Furthermore, serum CA-125 levels were significantly higher in patients with more extensive adhesions to the peritoneum, omentum, ovary, fallopian tube, colon, and cul-de-sac, or with ruptured endometrioma (P <.001, F test). We then classified patients with at least one of the three factors including dense omentum adhesion, ruptured endometrioma, and complete cul-de-sac obliteration as the high-risk group that required preoperative bowel preparation, and the others as the low-risk group. Receiver operating characteristic curve analyses set a cutoff point of 65 IU/mL, which gave a sensitivity of 76%, a specificity of 71%, a positive predictive value of 76%, and a negative predictive value of 93.2%.

Conclusion: Our results suggest that preoperative CA-125 assay is useful to decide which women should receive preoperative bowel preparation. Endometriosis patients with preoperative CA-125 levels higher than 65 IU/mL are at high risk for severe pelvic adhesions that warrant thorough preoperative bowel preparation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Biomarkers, Tumor / blood*
  • CA-125 Antigen / blood*
  • Endometriosis / epidemiology
  • Endometriosis / surgery*
  • Female
  • Humans
  • Predictive Value of Tests
  • Preoperative Care
  • ROC Curve
  • Regression Analysis
  • Risk Factors
  • Sensitivity and Specificity
  • Tissue Adhesions / epidemiology

Substances

  • Biomarkers, Tumor
  • CA-125 Antigen