What you can expect

By Mayo Clinic Staff

First trimester screening includes a blood test and an ultrasound exam.

During the blood test, a member of your health care team takes a sample of blood by inserting a needle into a vein in your arm. The blood sample is sent to a lab for analysis. You can return to your usual activities immediately.

For the ultrasound exam, you'll lie on your back on an exam table. Your health care provider or an ultrasound technician will place a slender, wand-like device in your vagina to send out sound waves and gather the reflections. The reflected sound waves will be digitally converted into images on a monitor. Your health care provider or technician will use these images to measure the size of the clear space in the tissue at the back of your baby's neck.

The ultrasound might take up to an hour. It doesn't hurt, and you can return to your usual activities immediately.

Test results are typically available in less than a week.

Oct. 13, 2012