IVF and ICSI have many similarities. However, the differences between them are very important. This post is dedicated to defining the differences between IVF and ICSI.
The introduction of intracytoplasmic sperm injection (ICSI) has resulted in a choice of fertilization methods between conventional in vitro fertilization by insemination (IVF) and fertilization by ICSI. Fertilization by insemination relies on the normal healthy functions of the sperm, and those can be bypassed by injection directly into the oocyte. Severe oligospermia (low sperm concentration), asthenozoospermia (low motility), or teratozoospermia (abnormal morphology) are all good reasons to use ICSI. However, many clinics routinely use 100% ICSI no matter what the diagnosis is. In the case of IVF, unexpected complete fertilization failure (CFF) in an individual cycle is a well-known phenomenon and is a risk to the success of IVF cycles. There are two techniques used to fertilize eggs during IVF: conventional insemination (simply referred to as IVF) or intra-cytoplasmic sperm injection (ICSI).
Before a man’s sperm can fertilize a woman’s egg, the head of the sperm must attach to the outside of the egg. Once attached, the sperm pushes through the outer layer to the inside of the egg (cytoplasm), where fertilization takes place.
Sometimes the sperm cannot penetrate the outer layer, for a variety of reasons. The egg’s outer layer may be thick or hard to penetrate or the sperm may be unable to swim. In these cases, a procedure called intracytoplasmic sperm injection (ICSI) can be done along with in vitro fertilization (IVF) to help fertilize the egg. During ICSI, a single sperm is injected directly into the cytoplasm of the egg.
Conventional Insemination:
In this technique, a woman’s eggs are surrounded by sperm in a petri-dish and ultimately one sperm fertilizes the egg. Conventional insemination (IVF) largely recreates the “best sperm wins” dynamic of natural conception. The fear with IVF is that in 10 – 15% of cases, patients experience total fertilization failure (TFF) where none of their eggs fertilize. That seldom happens with ICSI. Performing PGT after IVF is not recommended. Additionally, the embryologist will not know how many eggs were mature at the time of retrieval, or what their quality was.
ICSI:
In this technique an embryologist selects a single sperm from a man’s semen sample and injects it directly into the egg. The chief issue with ICSI is that this microsurgery costs an additional $1,500 – $3,000, can only be performed on “mature eggs” (ruling out ~20% of eggs that are retrieved), 5 – 15% of eggs are damaged in the process, success rates vary by embryologist.
ICSI is used in 90% of IVF cases that involve male factor infertility (issues with the man’s sperm count or motility) and 60% of cases that don’t.
Apart from the way the sperm is introduced to the egg, there are not too many other differences. The egg retrieval and the monitoring of the embryo remain the same. The transfer of the embryo does as well. The success rates for ICSI (50-80%) are higher than IVF without ICSI (50%). This does not however represent the pregnancy rates which are slightly higher for IVF without ICSI (27% vs. 24%). Live birth and birth defect rates have been reported to be quite similar between the methods.
ICSI Vs PICSI
Before a man’s sperm can fertilize a woman’s egg, the head of the sperm must attach to the outside of the egg. Once attached, the sperm pushes through the outer layer to the inside of the egg (cytoplasm), where fertilization takes place.
Sometimes the sperm cannot penetrate the outer layer, for a variety of reasons. The egg’s outer layer may be thick or hard to penetrate or the sperm may be unable to swim. In these cases, a procedure called intracytoplasmic sperm injection (ICSI) can be done along with in vitro fertilization (IVF) to help fertilize the egg. During ICSI, a single sperm is injected directly into the cytoplasm of the egg.
Why would I need ICSI?
ICSI helps to overcome fertility problems, such as:
-The male partner produces too few sperm to do artificial insemination (intrauterine insemination [IUI]) or IVF.
-The sperm may not move in a normal fashion.
-The sperm may have trouble attaching to the egg.
-A blockage in the male reproductive tract may keep sperm from getting out.
-Eggs that did not fertilize by traditional IVF, regardless of the condition of the sperm.
–In vitro matured eggs are being used.
-Previously frozen eggs are being used.
Will ICSI work?
ICSI fertilizes 50% to 80% of eggs. But the following problems may occur during or after the ICSI process:
Some or all of the eggs may be damaged.
The egg might not grow into an embryo even after it is injected with sperm.
The embryo may stop growing.
Once fertilization takes place, a couple’s chance of giving birth to a single baby, twins, or triplets is the same if they have IVF with or without ICSI.
ICSI was developed for men with poor sperm quality and quantity. Low sperm count, sperm motility, and abnormal morphology can be indications for ICSI. Abnormal morphology (shape of sperm) has been linked to poor fertilization. Fertilization can now be achieved for men where it previously seemed impossible. It is now used exclusively in some clinics, and it is especially important for couples who want to have their embryos genetically tested.
One of the reasons why it is so widely used now is so that the embryologists can look at the eggs and know the quality and maturation right after the egg retrieval. In conventional IVF, the egg quality and maturity is essentially a mystery because the eggs are surrounded by cells until the day after the fertilization. Fertilization rates are generally higher after ICSI compared to conventional IVF. The more embryos you have the better the chance of pregnancy!
One variation of ICSI is called “PICSI” which stands for physiological ICSI, and uses a specialized dish coated in a substance called hyaluronan. Healthy sperm are attracted to that enzyme and stick to it, they are later used to inject the egg with.
What if your IVF Lab does ICSI, But you want to try conventional IVF?
It’s in your best interest to do what the clinic does 99% of the time and not try to be one successful person on a procedure they do 1% of the time. Clinics have switched to ICSI for very very good reasons. It increases our patients success rates. It decreases chances of contaminating DNA from sperm during PGT. The embryologist will be able to examine and inject the nicest looking sperm. Think about it this way, you are preparing for the “Olympics” of baby making. We want to do anything in our power to shave 1 second off your timing so you can WIN the gold. A take home baby as quickly as possible.
Veering from the established standard of care for a lab (any lab) introduces another possibility to the mix; one of them making an error.
Why are you hesitating? Some people want it to be as natural as possible, but that’s not a good reason. Everything about the lab environment is not natural. Yes, fertilization failures do happen. This is not the thing to leave to chance, as you will get more than enough of that after the embryo is transferred back to your uterus. Allow the lab to do the procedures that give the highest success rates.
