I have a small one and they diagnosed it exactly as gabbster said. I also have tenderness and some pain in the right side of my abdomen, around where the tear is. It's more common if you have placenta previa (which I don't) or an anterior placenta (which I do). Report any bleeding or spotting right away, the faster they diagnose it the faster they begin keeping an eye on it. A small tear is not really problematic, however if it gets bigger it can be a problem.
Only reason im asking is I'm thinking about not getting the rhogam shot at 28 weeks but if I have any bleeding I'll have 72 hrs to get that shot.
I had a placental tear in my second pregnancy. Even if the cervix is closed, blood is able to squeeze by-I know, it doesn't make sense. You would have spotting and then the dr. would do an ultrasound to confirm. Mine was not so large and so everything was fine. The dr. put me on bed rest for a few days. Good luck. Don't worry about things you don't have yet. Be thankful you don't have it!
sorry typo, the last word is meant to be 'tear' not rear LOL