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Deep Dive

Is ICSI Required For PGS?

Patients are often told that ICSI should be utilized because the clinic will be using PGS testing to genetically screen their embryos.

PGS theoretically helps the doctor determine whether an embryo is chromosomally normal or abnormal so the doctor can make a good selection when deciding which embryo to transfer. To get this information, a few cells are cleaved off the outer layer of an embryo and sent to a lab for analysis.

The argument for why ICSI may be necessary with PGS is that ICSI helps make the test more accurate. When eggs are fertilized in IVF without ICSI, eggs are surrounded in a petri dish with a droplet that contains millions of sperm that all compete to fertilize the egg. Many doctors argue that all of the surrounding sperm that didn’t fertilize the egg will leave residue behind, and some of that genetic material may be inadvertently included when cells are removed from the embryo for PGS testing. They assert that ICSI improves testing accuracy, because the only genetic material that comes into contact with the egg is the individual sperm used to fertilize it.

Some doctors disagree, arguing that ICSI shouldn’t be a requirement for PGS testing. They believe that the residue from surrounding sperm doesn’t impact the accuracy of genetic screening when they are solely looking to determine whether that the embryo has the correct number of chromosomes.

How Common is it to Use ICSI for PGS?

Today, most doctors will tell you they require ICSI if they are going to run the PGS test. As you can see below, ICSI is now deployed in over 80% of all IVF cases where PGS is used to test the embryos, even when no male factor infertility is evident.

Many of these same doctors will claim they otherwise would not order ICSI, but they feel they need it for PGS. But the reality is that as far back as 2008 - 2012, when PGS was used in just 7% of IVF procedures, ICSI was already used in nearly 65% of non-male factor cases. So to presume doctors are eager to perform ICSI only because they believe it helps with PGS is probably an overstatement.

But that doesn’t necessarily settle the debate as to whether deploying ICSI is a requirement if we want to use PGS. The reality is that when PGS is used to test embryos for IVF, it makes no meaningful difference whether ICSI is used or not.

Today, many of the third-party laboratories that run the PGS analysis do not require that the embryo was fertilized using ICSI, though they may be slow to admit it for fear of upsetting the referring clinics who are eager to perform ICSI.

What about PGD?

On the other hand, ICSI is absolutely a requirement when the intended parents want a test called PGD to be performed. PGS and PGD are different tests, and while both require your clinic to biopsy the embryo and send the sample to an outside lab, what the lab ends up looking for are entirely different things.

In PGS, we are only counting chromosomes in the embryo’s cells, whereas in PGD we are looking to detect the presence of specific genetic mutations related to disease. In the case of PGD, the lab cannot tolerate excess genetic material around the outside of the embryo, and so ICSI is indisputably necessary.

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