Pittaway D E, Fayez J A
Am J Obstet Gynecol. 1987 Jan;156(1):75-6. doi: 10.1016/0002-9378(87)90207-9.
Serum CA-125 antigen levels were measured by radioimmunoassay before and during menses in women with and without endometriosis. Mean CA-125 levels were significantly increased in both groups during menses. Samples obtained during menses represent a potential source of elevated levels and false positive results.