I am currently 20 weeks pregnant. at my ultrasound anatomy scan i was told that it looks like my baby has an "extra heart vessel" they were concerned about. i am being referred to maternal fetal medicine. what could this possibly be?

Without having the report in hand and the chance to review it with the radiologist it is hard to interpret the wording used. The cited referral is the standard of care. It helps focus on whether or not there is a problem and if so what plans need to be made for future care.

If the cardiac function is normal and the vessel not blocked, they will likely observe and follow up with additional studies. Watch for signs of shortness of breath and feeding difficulty.