I recently had the maternal serum screening test done. The doctor called me and said that the test came back positive for trisomy 18. I am 29 years old and I would like to know my risk of having a child with trisomy 18. I have also been scheduled for a level II ultrasound and I would like to know what they will be looking for in the ultrasound.
The blood test was just a screen. Your chances are still probably low for trisomy 18, but if the ultrasound adds suspicion, nothing short of an amniocentesis will give you your definite answer.
Ultrasound will check for growth problems and structural abnormalities that may indicate the need for amnio.