Abnormal Quad Test Results

[MaRangcom]

I just got a call from my doctor's office letting me know my quad tes results were abnormal.  Her recommendation was to have a level II Ultrasound and/or an amniocentesis.  I am  32 years old, 18 weeks pregnant, all my other blood work results came back normal, baby's heartbeat and growth seems to be going accordingly.  What are the chances of these results truly reflecting abnormalities in my baby?  I called my hospital and the soonest they can work me in to have my ultrasound is 3 weeks from today.  I am extremely nervous and concerned about these results.  Thanks to all for your input.

[Lisa Kessler, MS, CGC]

Hearing that any test is abnormal during pregnancy can be quite scary. I hope this information helps you understand what the abnormal test many mean and you can be a less nervous the next three weeks.

The quad test is a screening test. This means that it cannot diagnose a problem in your baby, it can only tell you if you are in a risk category where some additional testing should be discussed.  As you know, it is a blood test done on the pregnant mother, and is typically done between 15-18 weeks of pregnancy. A lab analyzes the maternal blood for four pregnancy chemicals and combines these results with other maternal information, such as age and how far along the pregnancy is, to determine the chance the developing baby may have an open neural tube defect (open spina bifida), Down syndrome (also called trisomy 21) or Edward syndrome (also called trisomy 18).

This test is correctly positive in about 80% of pregnancies with fetal open neural tube defects, 80% with Down syndrome, and about 60% for Edward syndrome (trisomy 18). This does not mean those are the chances your baby has a problem, those numbers just describe how good the test is overall.  

In order to have the good detection rates described above, the quad test is designed to be positive or “abnormal” in about 5% of all pregnancies. Because the conditions described above are uncommon, though, only about 2-3% of all positive test results will confirm Down syndrome, trisomy 18 or an open neural tube defect in the developing baby.

You should call your doctor and ask what problem the quad test was abnormal for, and what specific risk figure was given by the lab.  This can help you determine how concerned you should be.  Your doctor’s office may also be able to help you get an appointment more quickly.