Consequences of a falsely elevated CA 125

A 41-year-old nonparous female presented with a several month history of right lower quadrant abdominal pain. The pain was described as deep twinges of discomfort that had no correlation to the menstrual cycle, bowel, or bladder function. Her primary care physician ordered a pelvic ultrasound examination that showed a cystic mass measuring 5.1 x 4.8 x 3.4 cm in the region of the right ovary. The patient was referred to a gynecologist who found a normal examination, aside from some vague tenderness in the region of the right ovary. There was no history of ovarian cancer in this patient's family. The patient was advised of the findings and opted for a repeat pelvic ultrasound examination and measurement of serum CA 125. The second pelvic ultrasound examination, performed 6 weeks after the first, showed that the cyst was a well circumscribed sonolucent lesion. The cyst was smaller than initially noted, with a maximum diameter of 2.2 cm. The serum CA 125 concentration measured by the Abbott MEIA procedure (Abbott Diagnostics, Abbott Park, IL, USA) was found to be elevated at 352 IU/mL. The reference intervals are as follows: 0-35 IU/mL, ovarian cancer unlikely but not ruled out; 35-65 IU/mL, compatible with ovarian cancer, cancer of other organs and benign gynecological disorders; >65 IU/mL, highly suggestive of ovarian cancer. Given the benign appearance of the cyst on ultrasound examination and physical examination, the serum CA 125 measurement was repeated and still found to be elevated at 348 IU/mL (Abbott MEIA procedure). At this point the patient requested the opinion of a gynecologic oncologist at a separate teaching center, and subsequently underwent a total abdominal hysterectomy and bilateral salpingoophorectomy. Examination of the cyst by a pathologist showed no evidence of malignancy and the patient recovered uneventfully. The referring gynecologist and gynecologic oncologist were at a loss to explain the discordance of the CA 125 values available at their respective centers.(DBO)