Can women with cerclage get false positive fetal fibronectin test? if yes, why?

False positive: False-positive results can occur if a woman has recently had : 1) A pelvic exam. To reduce the risk of a false-positive result, it is important that a fetal fibronectin test be done before a manual pelvic exam. 2) Sexual intercourse. 3) Uterine contractions. 4) Bleeding from the vagina. Discuss this with your OB if you have questions