Every appointment they will check for abnormalities. The quad screening is not always offered and is voluntary. Not all insurance covers it, so you'll want to ask. The test is also not 100%, it just indicates higher risks for what they test for.
No, the quad screening is a one time test. They draw blood and place it on a piece of paper and sent it to the lab. You'll know if you're getting screened because they will tell you.
So everytime they take your blood they test you for eveything like that ?
I took a quad screening at 13 weeks. It's a blood test that checks for down syndrome and trisomy. There are also ultrasound tests and things they look for when checking for downs. You can request a quad screening if they don't offer one.