Cervical fluid oncofetal fibronectin as a predictor of early ectopic pregnancy. Is it affected by blood contamination?

OBJECTIVE

To evaluate (1) the diagnostic usefulness of oncofetal fibronectin (fFN) in the cervical fluid in unruptured ectopic pregnancy, and (2) the contribution of maternal blood contamination of the specimen to the test results.

STUDY

DESIGN

A total of 111 cases in the first trimester of pregnancy, including 12 cases of ectopic pregnancy, 26 of spontaneous abortion and 73 of viable intrauterine pregnancy, were studied. fFN was determined with a commercial enzyme-linked immunosorbent assay kit with a threshold of 50 ng/mL in cervical fluid. To determine the effect of blood contamination on the fFN assay, the positive rate of the fFN test was examined when maternal blood in the first trimester was mixed with the dilution buffer.

RESULTS

Eighty-three percent (10/12), 38% (10/26) and 12% (9/73) of cases with ectopic pregnancy, miscarriage and normal pregnancy, respectively, were positive for fFN. The positive rate in ectopic pregnancy was significantly higher than in normal pregnancy and spontaneous abortion. The test was positive for fFN in 8% with 0.5% of blood contamination, 67% with 1% contamination and 100% with 10% contamination.