Menstrual cyclicity of CA-125 in patients with endometriosis

OBJECTIVE: To examine the serum levels of CA-125 in the menstrual, follicular, and luteal phases of the menstrual cycle in women with endometriosis and to determine if serum CA-125 levels drawn during menses improve the clinical utility of the test in diagnosing endometriosis. DESIGN: Serum CA-125 was measured in the menstrual, follicular, and luteal phases of the cycle preceding surgery. CA-125 levels for each phase were categorized by postoperative diagnosis and endometriosis stage. SETTING: The reproductive endocrine unit of a tertiary care university-affiliated hospital. PATIENTS: A total of 65 patients were recruited from the Fertility and Endocrine Unit and the Gynecology Service of Brigham and Women's Hospital. MAIN OUTCOME MEASURE: Serum CA-125 levels were measured by an immunoradiometric assay and were stratified by menstrual cycle phase, diagnosis, and stage of endometriosis. The menstrual cycle phase was confirmed by serum estradiol and progesterone measurements. RESULTS: Serum CA-125 levels in patients with stages II to IV endometriosis were significantly elevated in the menstrual phase compared with levels drawn in the nonmenstrual follicular and luteal phases. The sensitivity and specificity of CA-125 for the diagnosis of endometriosis were not significantly better in the menstrual than in the follicular or luteal phases. CONCLUSIONS: Despite menstrual cyclicity of CA-125, measurement of serum CA-125 during menses does not improve the clinical utility of the test in the diagnosis of endometriosis.