Prenatal Testing: Quad Screen vs. CVS vs. Amniocentesis

At some point during every older mother’s pregnancy journey comes the dreaded  Prenatal Testing.  This is when all the statistics and risks we hear about genetic, chromosomal, neural tube, and other disorders come to a head… to provide us a healthy dose of additional worry.

Given my age, I was definitely concerned about Down syndrome.  What I was too ignorant to be concerned about, until I was so informed by my doctors, were the host of other  potential problems that could occur – including the various trisomies, fragile x syndrom, neural tube defects, etc, etc.  I remember at one point sitting with a genetic counselor, 2-page list in hand, and skimming all the potential issues and my baby’s risk of having these issues.  Worse, the list was segregated by age group – so I could see that for the younger age group, wherein the risk of a particular disorder might be 1 in 2000, for me it might be 1 in 200.  Scary stuff.

Which is precisely why prenatal testing is so important.  My understanding is that younger mothers are typically tested using simple ultrasound and blood testing techniques (with more invasive measures offered only upon request and doctors’ agreement).  However, in my case, my Advanced Maternal Age prompted the doctors to provide me with 3 separate test options, all with their own pros and cons:

1. Quad Marker Screen:  Between the 15th and 20th weeks of pregnancy, this is a blood test performed to determine the levels of 4 substances within the amniotic fluid.  These levels are then analyzed to see if they fall within acceptable limits; if not, additional more invasive testing may be recommended.  The major pro of this approach is that there is no risk to the baby – it’s just a simple blood test.  The con is that results are not diagnostic; that is, they can only identify certain increased risks of an issue – which would be the signal for additional testing.  They are also not 100% accurate – e.g. not 100% of Down syndrome cases (I believe it’s somewhere around only 80%) can be predicted with this test.
2. Chorionic Villus Sampling (CVS):  Usually performed between the 10th and 13th weeks of pregnancy, this test uses an ultrasound to guide a thin catheter through the cervix or the abdomen to draw a sample of placental cells.  These cells are then tested to diagnose chromosomal or genetic disorders.  The pros of this approach are its levels of diagnostic accuracy (98-99%), the timing of potential diagnosis (very early in the pregnancy), the inclusion of DNA in the sample (allowing for paternity testing if desired), and the nice-to-have ability to determine the baby’s gender very early in the pregnancy.  The cons of this approach are the fact that it doesn’t identify neural tube defects, the elevated risk of miscarriage (somewhere around 1%), a risk of amniotic fluid leakage, and a risk of infection (as with any invasive procedure).
3. Amniocentesis:  Usually performed between the 14th and 20th weeks of pregnancy, this test uses an ultrasound to guide a thin needle through the abdomen to draw a sample of amniotic fluid.  This fluid is then tested to diagnose chromosomal, genetic, or neural tube defects.  The pros of this approach are its levels of diagnostic accuracy (over 99%), the inclusion of DNA in the sample (for paternity testing if desired), and the ability to determine the baby’s gender.  The cons of this approach are a small risk of miscarriage (less than 1%), a risk of infection (as with any invasive procedure), and a rare risk of injury to the baby or preterm labor.

So then comes decision time.  Do we want to go with the no-risk procedure, yet give up complete diagnostic ability?  Do we want to go with a more invasive procedure, yet introduce a risk of miscarriage?  If we do go with a more invasive procedure, do we want to do the more common “tried and true” amnio, or the newer CVS that will provide results weeks sooner?

Then comes the ethical debate… Would we consider terminating a pregnancy depending on the type of problem that was revealed?  If not, then why do anything but the least invasive test?

In the end, we decided to go with CVS testing.  Given our previous miscarriage along with the risk of miscarriage that this test would introduce, it wasn’t an easy decision.  But ultimately we liked the fact that we would know what we were dealing with sooner than later.  Also, we reasoned that the miscarriage risk would go down with an experienced doctor, so I sought out to find the best local one I could.

Fortunately, I was quickly pointed in the direction of a wonderful local doctor who had to date performed over 25,000 CVS procedures.  His success rates were high and past patients raved.  I checked out his error rates and was satisfied.

The first appointment is a genetic counseling session.  We are ushered into a little office with a genetic counselor who questions us and then basically draws out our family medical history on a piece of paper.  She reviews the 2-page RISK LIST, our eleveated risks due to maternal and paternal age, and finally discusses the CVS procedure in detail.  She concludes that we (I) are good candidates for the procedure with no glaring risk of fetal abnormality.  We schedule a date.  I will be 12 weeks pregnant at the time of the procedure.

The night before I’m really nervous.  Praying for no infection, leakage, or miscarriage.  Fortunately, work keeps my mind occupied (the silver lining of a stressful job)?  The procedure is scheduled for a Friday so I can do the required bed rest for 2 days. 

Once we arrive, we’re seen by an ultrasound technician.  The technology here is amazing!  MUCH better than the ultrasounds we have received at my local OB-GYN’s office.  We can see the little bean in 3D, jumping, moving.  He shows me his heart rate.  We hear the heart beating (and all the other noises in there – who knew how loud it was?  No wonder babies love the sound of vacuum cleaners).  He takes brain and other measurements and says that everything looks normal.  He sees that I am nervous.  Reassures.  Says this doctor is the best on the west coast.  It will be fine.

We are then led into a room tricked out with some sort of super-sonic ultrasound machine.  Since the procedure involves EITHER a transcervical or transabdomenal catheter, I ask which one I’m going to get.  The nurse says the doctor prefers transcervical (quicker, easier, less painful) so he will do that.  I agree but internally wish for the other method.  Somehow seems less invasive to me.

The doctor arrives.  Given the number of these procedures he performs, I am expecting a kinda “assembly-line” experience.  A detached persona.  To my surprise, it’s the complete opposite.  The doctor is cheerful, engaging.  Asks about our summer vacation plans.  Shares about his most recent trip, a family gathering in Texas.  Chats while he positions me appropriately (maybe this is part of the plan?  To keep our minds occupied?)  Tells me to BREATHE and RELAX.  That if I am not relaxed, I will start to contract, and that may impact his ability to draw a large enough sample.

The nurse turns on the ultrasound.  Again, I’m amazed at the level of detail.  At only 12 weeks!  The doctor prepares… something… I’m not really in the best position to see.  Then he begins to guide the catheter, watching the ultrasound monitor the whole time.  Relax, he says, breathe. 

He stops.  Okay, you’re starting to contract…  see?  Points to the monitor.  Now I only have this much space.  I giggle sheepishly, nervously.  Oh sorry.  I concentrate on deep breathing.  I know it’s not going to work.

He tries again.  Breathe, okay, just breathe.  Now it’s done.  I sit up.  He is looking at the sample.  I’m sorry, he says, it’s not enough.  We will have to go through the abdomen.

Wow – Two For The Price Of One!  I can barely contain my excitement. 

Belly cleansed.  Numbing shot.  Ouch.  Now the needle and catheter.  Don’t look, it makes it worse.  I can’t really see anyway, with my head positioned at a lower angle than the rest of my body.

I feel the pressure of the needle catheter.  He gently guides it up and down to get the sample.  Okay, done.  Good – great sample here.

I sit up as nurses start cleaning up.  Hubby looks shocked.  What?  He wants to know if it hurt.  Then he shares that he is certain he saw the baby on the ultrasound monitor looking towards the needle as it was poking around.  He says the baby’s face had been turned away but then rotated towards the needle and was watching as the sample was being taken. 

Next two days are uneventful.  Bed rest.  No pain.  Just watching watching watching for any bleeding, any sign of miscarriage.  Thank goodness… Nothing.  Start to relax.

We had paid extra for FISH results…  these are not full results, but high level preliminary results that look at a few of the most common chromosomes for issues.  These results would be provided within 72 working hours.  Full results would come about 2 weeks later.

Glad I paid extra for the faster results.  Next few days are excruciatingly slow.  Every time my cell phone rings I grab it to look at the number.  Finally, at the end of a Wednesday work day, I get The Call.

Everything looks great.  No issues with the preliminary results.  Final results will be completed in two weeks but assume that no news is good news – no call means everything looks normal.  Happy.  It appears that she is about to say good-bye and hang up.

Wait – I say.  What about gender?  Can’t you tell gender too?  She pauses, teasing.  Do you really want to know?  YES!  She pauses again, she likes this part of her job.  You’re having a baby boy.

A baby boy!  A healthy baby boy!  WOW.  I can’t believe it.  I’m so lucky!  Bursting.  Already thinking of special ways to tell my husband.

Two weeks comes and goes.  No call.  We’ve just gotten through the first anxiety-ridden phase of pregnancy.  We are happy with our testing decision.

I have friends who have opted for both the Quad Screening and Amniocentesis testing options.  They are also happy with their decisions.  Those who opted for the Quad Screening were comfortable with the level of accuracy and in their philosophy that no matter what the results, it wouldn’t change the direction of the pregnancy (e.g. termination would not be considered), so why go through the risks of more invasive testing?

Those who opted for the Amniocentesis were more comfortable with the fact that it is a “tried and true” procedure (vs. the newer CVS procedure) with a lower risk of miscarriage and also the ability to conduct neural tube analysis. 

So there’s no right answer for everyone – simply what each family is comfortable with.  Ultimately the question you have to ask yourself is what level of diagnosis and procedure risk you would be comfortable with in order to maintain a stress-free (as much as possible) ongoing pregnancy. 

The one thing I did learn was to try not to put too much stock into “The Statistics” for my age.  A statistic is a statistic.  I had to keep reminding myself that even if I had a 1 in 100 chance of a problem, that still meant I had a 99 in 100 chance of that problem NOT occurring.  Regardless of the odds, if you happen to be the person who is 1 in 100 or 1 in 1000000, the statistics are meaningless.  All we can do is try to be as healthy as possible with a little luck thrown in.

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