GBS Test

So I went to the doctor for my 36 week appointment and they told me its time for the GBS test. Now I've been reading up on this before I even got to my appointment, but what threw me off is they had me do it myself. They briefly explained what I needed to do, but after reading so many different experiences I don't think I did it right. They told me just to swab from front to back (same swab) and put it in the tube. I just want to make sure it's accurate because I want my baby to get everything they need to avoid risking infection. Has this happened to anyone else?