Abstracts from Obstetrics and Gynecology


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



Cheng YM; Wang ST; Chou CY


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 plus minus 0.9, 40.3 plus minus 2.8, 77.1 plus minus 3.5, and 182.4 plus minus 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.



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