I am a nerd. An over-researching knowledge-seeking math and science minded nerd.
Knowing that my AFP is elevated and that elevates my risk for birth defects or placenta problems is scary. But what is AFP? What is a normal level? What exactly does all of this mean? How are neural tube defects or placenta problems indicated by this one measurement? (They don't exactly seem like related complications.)
Yes, sometimes google is a scary place to look for answers. But if you know to stick to the science and avoid the more informal sources - you can really get great information.
AFP (alpha-fetoprotein) is produced by the liver of a fetus. Its not something produced by a healthy adult liver so in non-pregnant adults, AFP should be found in trace amounts. AFP produced by the fetus is excreted into the amniotic fluid and then some of this protein crosses the placenta and is then found in the mother's blood. All pregnant women should have AFP in their blood - in fact too little AFP in maternal serum can be an indicator of Down Syndrome. The question is - why are my levels elevated? And exactly how elevated are my levels?
Let's start with that second question first. AFP levels are reported as "multiples of the median" or MoM. As gestational age and maternal weight change throughout pregnancy, AFP levels vary widely. So they are not reported as absolute values tested from maternal serum. Rather they are reported as how much they deviate from what is considered normal for a particular gestational age and maternal weight (and a few other factors including race and diabetic status). So an AFP level of 1.0 is considered "perfect" - exactly the median. An AFP of 0.5 means the mother has half as much AFP as you would expect. And an AFP of 2.0 means the mother has 2 times more AFP than you would expect. On the low end, anything below 0.5 is considered too low. On the high end, there is some controversy. Some labs use 2.0 as their cutoff. While other labs use 2.5 - stating that 2.0 increases false positives significantly without a marked increase in effectively detecting more birth defects. My lab uses 2.5. What was my level? 2.56. Severe defects are usually seen when MoM values are above 7.0 and my lab recommends a repeat draw for anyone between 2.5 and 3.5. So, in some ways, that's comforting. My level is not grossly abnormal. That being said, I'd obviously feel much MUCH better if that number was a helluva lot closer to 1.0.
So what causes elevated levels in mothers? There are 2 known causes and then there is the "it's not necessarily a problem" explanation so I'll start with that first.
This is the most common outcome. I have to keep telling myself this. Some babies make more AFP than others. Some completely healthy placentas let more of the protein cross into the mother's blood. It is not necessarily an abnormality (particularly at my level) and does not necessarily indicate a problem. These are the "false positives" with this test and 90% (YES NINETY PERCENT) of mothers with elevated AFP fall into this category.
Now let's go into the concerns with elevated AFP that apply to the remaining 10%.
1). Neural tube defects. These are defects where the baby's brain and/or spine do not close properly and part of this system remains literally open. These disorders range from things as serious as anencephaly (if you google it, don't look at pictures) to more minor cases of spina bifida and everything in between.
The opening in this system allows much higher amount of AFP to be leaked into the amniotic fluid than would normally be excreted by a baby with a closed system. More AFP in the amniotic fluid means more passes the placenta and more gets into mom's blood.
While NTDs are the most common defects associated with elevated AFP, it can be caused by any abnormal opening in the baby. So it's important to rule out other problems like an open abdominal wall.
The second concern?
2). Abnormal placenta. It is possible for the baby to be fine, for the AFP levels in the amniotic fluid to be normal, and for the levels in my blood to be elevated due to problems with the flow back and forth between the placenta. (It seems that "leaky placenta" is the jargon for this.) A placenta that is not allowing proper flow back and forth has been linked to many complicated and very serious third trimester problems. These include: intra-uterine growth restriction (IUGR), preterm labor, premature placental deterioration, placental abruption, and still birth. All of those things life threatening for the baby.
So what can be done about any of this?
1). Ultrasounds to rule out birth defects. Technology has come a LONG way. With specialized equipment, extremely trained specialist, and most recently the addition of 3D and 4D ultrasounds, I've read that ultrasounds are now almost 99% effective at identifying birth defects when using a specialist trained to look for specific problems.
2). Amniocentesis. This is a little more controversial and not used as much as it used to be for this problem. Many things can be determined from sampling the amniotic fluid. A full chromosomal analysis of the fetus can be done, but an open abdominal wall is not necessarily a chromosomal problem. So while amniocentesis can be used to definitively (100%) diagnose something like Down's Syndrome, it is not 100% in identifying all birth defects - specifically the ones we are concerned about here. The other thing amnio could tell us here is how much AFP is in the amniotic fluid. If the AFP in the fluid is elevated, that points more towards problems with the baby. If the AFP in the amniotic fluid is normal, that points towards problems with my placenta.
So what's the controversy with amnio? It requires sampling the amniotic fluid. That is insertion of an insanely long needle through my abdominal wall and uterus, and into the baby's sac to withdraw the fluid (while watching via ultrasound so as to not go too far and stick the baby). Invasive is an understatement. And it does come with an small elevated risk of miscarriage after the procedure.
Given that amnio isn't a definite answer for this problem, it carries some risks, and ultrasounds have become so amazingly advanced, amnio isn't likely something we would consider.
3). Ultrasounds and non-stress tests to monitor possible placenta problems. Let's say we are fortunate enough that ultrasounds rule out birth defects with the baby. How on Earth do you rule out problems with the placenta? Unfortunately, you don't. You just monitor them very very closely. This is done with ultrasounds and non-stress tests done frequently (every 2-3 weeks) to try to stay ahead of possible problems like growth restriction, preterm labor, etc . . . BEFORE you ever get to the concerns of placental abruption or still birth.
So that is where we are. As much as I know that my levels aren't *that* high and as much as I know that 90% of people flagged by these tests have no problems, I really don't care how this re-test comes out. I NEED the high risk consult. I need someone who knows what they are looking for to tell me that my baby and my placenta are okay and monitor them with a trained eye. I KNOW my previous losses are completely unrelated to this. But in 2 weeks we cross over from being in the miscarriage category to the stillbirth category, should something go wrong. And I can not take any chances, no matter how slim, that we could possibly be adding a late second trimester or third trimester still birth to my fucked up obstetric history.