Embryo Testing

So far so good, the first pregnancy test was positive!  They had me check a blood pregnancy test 2 weeks after the egg retrieval.  This makes sense, since normally I tell patients to check a pregnancy test two weeks after ovulation/conception potentially occurred.  This usually ends up being around the time of the missed period in women who have regular cycles.

Since the embryo transfer occurred at Day 5, the wait was only 9 days, so it didn’t feel like eternity to me.  Since I’ve spent most months of the past two years waiting two weeks from ovulation to the pregnancy test/period, 9 days wasn’t so bad.

Next, I will check the hCG level again to make sure it’s rising appropriately.  From there, I’ll have to wait another couple of weeks for my first ultrasound to see if a fetus is present.  And even then, we’ll want to check a little later to make sure it’s still viable.  So there’s still a lot of waiting to do.

I’m aware of all of the possibilities.  There is a possibility that the pregnancy will end in miscarriage again.  With IVF pregnancies, the risks of ectopic pregnancy are much higher.  An ectopic pregnancy means that the embryo implants somewhere outside of the uterus, usually in the fallopian tube.  If not detected early enough, and it keeps growing, the tube could rupture and cause hemorrhage, which would be an emergency, requiring surgery.

In many cases such as this when we know someone is pregnant from early on, we can often detect an ectopic pregnancy early based on the hCG levels rising more slowly than normal.  If detected early, a medication called methotrexate is often used to treat it medically.

Another possibility is twins.  We only transferred one embryo in the hopes of reducing the chances of twins, but sometimes the one embryo decides to split and becomes twins, or rarely more.  I hope this doesn’t occur, since twins are at high risk for complications like preterm delivery.  Also, when twins share the placenta (called monochorionic twins), there’s a higher risk for them to have an unequal distribution of blood supply.  It’s called twin-twin transfusion syndrome, and in some cases could be severe.

For twins that come from two separate eggs and sperm, such as if two embryos were transferred or a woman naturally ovulated two eggs, you’d end up with fraternal twins and wouldn’t have to worry about the twin-twin transfusion syndrome.  You’d still have to worry about risks like preterm delivery, though.  Not to mention the craziness of having two babies instead of one.

We decided not to test the embryos for genetic (chromosomal) disorders, which is why we did what’s called a fresh embryo transfer.  Many people choose to do the testing, which requires freezing the embryo to allow for the testing, and then transferring it into the uterus a little later.  That would have been a frozen embryo transfer.

The testing I’m referring to is called preimplantation genetic screening (PGS).  The test is designed to screen for chromosomal disorders in general, as opposed to looking for a specific disorder.  For people who have a known disorder, it definitely makes sense to test the embryos for that specific disease, and to only implant the unaffected embryos.  This targeted testing is called preimplantation genetic diagnosis (PGD).

Based on my limited knowledge, I don’t think there’s a right or wrong answer when it comes to the decision to test the embryos.  I’m 37 yo, will be 38 soon, so statistically the chances of chromosomal disorders are less than say, for a woman who is 40 yo.  But since I’m over 35, there is still a higher chance than in a younger woman.  One of my friends who had to do countless cycles of IVF before finally having her baby said that they didn’t do the testing of the embryos.  Her doctor mentioned the possibility of false positive results- meaning the results can occasionally show that there is an abnormality when none is present.  Also, she was concerned about the theoretic risks of disrupting an embryo at its early stages to perform the genetic testing.

I think what my friend’s doctor was referring to is the embryo testing that is most commonly performed now, called the blastocyst biopsy.  When the embryo reaches the blastocyst stage at about Day 5, it’s made up of more than 100 cells.  The biopsy takes cells from the outer cell mass which eventually becomes the placenta, as opposed to taking a biopsy from the inner cell mass which will become the baby.  Sometimes the biopsied cells don’t reflect the actual cells of the baby, and therefore you could end up with erroneous results.

My impression is that the errors don’t happen too frequently, which is why many people are commonly having the testing performed.  I have friends and colleagues who have had the testing performed, and their babies turned out just fine.  Not to mention celebrities like Chrissy Teigen have been open about doing IVF.  She mentioned knowing the genders of the embryos before implantation, so they clearly had the testing performed.

The benefit of having the testing done is to greatly reduce the risks of a chromosomally abnormal baby.  Because many chromosomally abnormal embryos/fetuses do not develop beyond a certain stage, this would theoretically reduce the risks of miscarriage.  Also, it would be terrible to later do the genetic screening during the pregnancy, only to find out there is an abnormality.  That would result in the difficult decision for many couples as to whether to terminate the pregnancy.

Our thought was that if there is a chromosomal abnormality, then there’s a decent likelihood that either the embryo wouldn’t develop well enough for transfer, or that there would be a miscarriage.  Our doctor said that in the many years he’s been doing IVF, there have only been a few times that there ends up being an abnormality like Down Syndrome that is detected later in the pregnancy.  When it comes to gender, that doesn’t matter at all to us.

Of course, I’m a little nervous about the prospects of having a miscarriage, or later doing the blood test in the pregnancy and finding out there’s an abnormality.  In case this embryo doesn’t take, we thankfully have a frozen one as backup.  Apparently it is possible to thaw it to test, and then refreeze it.  There would be more of a chance with that scenario to damage the embryo during the process (compared to if we’d decided to do the testing in the first place).  So it may not be worth it.  But if neither embryos take and we have to go through the egg retrieval process again, then it would make sense to consider the PGS from the get go.

 

 

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