Preterm Labor Test?

Ke
Given my history of contractions starting at 25weeks, being put on terbutaline in the past, and my husband's job requiring him to fly all over the country monthly my dr wants me to be swabbed for the fetal Fibronectin test this Friday to see my chances of another preterm labor scare. 
Has anyone else had this? 
In your experience was your positive accurate, did you go into preterm labor? How quickly did you get results back? 
I'm so nervous because she wants to start me on weekly shots and steroids and I'm 15 hours away from any family and feeling kind of down with all these worries with 3 other kids to take care of. We just moved here so we don't really have friends here if anything happens. So I'm a nervous wreck.(Ok whine fest over)