AFP testing

[Guest guest]

Since there has been a lot of mention of AFP (alpha-feto-protein) and

the triple screen (a test which measures AFP and other stuff), I though

I might take this time to clarify AFP testing. Unlike a lab test with

an absolute result (yes or no), the AFP measurement is SUGGESTIVE that

there might be a genetic problem with the fetus. It has never (or

should never) be suggested that this test can determine anything certain

about the fetus, but rather gives an indication that something might be

abnormal in the pregnancy. Origianlly, it was done because it was noted

that pregnant women who had babies with open neural tube defects (spina

bifida and the like) frequently had an increased level of AFP in the

mother's blood. If the AFP came back high, then further tests were done

to look at the fetus, but a high AFP did not mean you were having a baby

with spina bifida, but rather suggested there was an increased risk.

Many women were told they had elevated AFP..... some did more testing,

others did not. So if you were one who was told " your AFP is high " but

declinded further testing and then gave birth to a healthy baby, you

might be inclined to say " hey, the doctor was wrong..... my baby is

fine " , when in alll likelihood, the doctor never said " your baby will

have spina bifida " , but rather " with these AFP results, your baby has an

increased risk for spina bifida. " Slight difference in wording, but a

drastic difference in interpretation.

The same test is also a predictor for DS, though at a lower level of

accuracy. A low AFP result can suggest that the baby might have DS, and

further testing will be offered. Not all women who have low AFP results

will have a baby with DS (false positive result), and not all moms who

have babies with DS will have a low AFP (false negative result).......

currently only about 60% of the mom's who are carrying babies with DS

have a low AFP. If a doctor tells you, " your AFP is fine, so your baby

is fine " he really means....... certainly your baby could have still DS

or a many other things that don't affect AFP levels, but your risk is

lower than if you had an abnormal AFP. If a doctor tells you " your AFP

is low " , then he's NOT telling you that you will have a baby with DS,

but rather you are at an increased risk for having a baby with DS.

So, the moral of the story here is: AFP gives an indication if further

testing needs to be done, it does not diagnose anything on it's own.

In general, laborary testing is accurate, although almost everyone has a

story where someone they know got a wrong lab result. Inaccurate

results sometimes happen, but more often than not, it's how the results

are presented and interpreted that's the problem.

Taking off my scientist hat now.............

, mom to (10), (8 DS), and Sammy (7)