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Serum CA-125 in preoperative patients at high risk for endometriosis
Ya-Min Cheng1, Shan-Tair Wang, Cheng-Yang Chou
1Department of Obstetrics and Gynecology, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
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.
