abnormal blood test results

My doctor called yesterday and said my apf tests came back abnormal. The cut off for normal is 2.5, I'm at 3.75, spina bifida is a 7-8. He said not to worry that these tests are not always accurate, high percentage of false positives. That's it's not a diagnostic test, just says that something may be wrong. 
So our next step is going to a specialized ultrasound place to have everything checked out. I'm 18 weeks right now. I was a hysterical wreck yesterday, and now have to get through a few more days...
Has anyone had abnormal results that ended up being ok?