ICSI - Intra Cytoplasmic Sperm Injection

ICSI (Intracytoplasmic Sperm Injection) may be used as part of your IVF cycle. With ICSI, we inject a single sperm directly into the centre of the egg. This method is especially successful in overcoming male infertility problems.

For patients using ICSI, the treatment process is exactly the same as a standard IVF cycle. The only difference is the fertilisation technique the embryologists use in the lab on the day your eggs are collected.

How does ICSI work?

Since it only takes one single sperm to fertilise the egg, our highly experienced Fertility Scientists known as Embryologists, search and catch the ideal sperm and inject this single sperm directly into the centre of the egg.

Who can benefit from ICSI?

ICSI can be an option for patients who have:

• an abnormally low sperm count or poor motility
• a high percentage of abnormal sperm or few healthy sperm
• sperm obtained via testicular biopsy or micro TESE
• previously low fertilisation rates with standard IVF
• undertaken Preimplantation Genetic Testing (PGT)

If you don’t fit one of the above categories, however, you’re probably better off using standard IVF rather than ICSI. There’s growing evidence to suggest that IVF success rates are actually higher when standard insemination techniques are used. The takeaway? Think of ICSI as a viable Plan B.

The ICSI process

Introduction

ICSI can be performed with either fresh sperm or thawed frozen sperm. Our experienced Embryologist choose the ideal sperm from the sample. The ideal sperm has an oval shaped head, normal tail and is moving fast. Being able to identify morphologically normal sperm is a skill that our Embryologists develop over many years, with constant fine tuning, to select the ideal sperm for every egg. The ideal sperm will have not only the normal morphology but also good motility (movement).

Step 1: Sperm selection

It’s a real skill to spot morphologically normal ‘ideal’ sperm cells – they need to have a certain shape and size in many parts of the sperm cell. These sperm have an oval head and a long tail which they use to help them swim. Men with infertility issues often make fewer such sperm, which is why sperm selection for ICSI is so vitally important.

The next thing to consider is sperm motility or movement. Essentially, a sperm with good motility is able to move itself around and penetrate an egg. This movement depends on the length and size of the sperm’s tail. Tails that are curly or doubled up can’t swim as efficiently.

In order to select the best sperm for ICSI, the Embryologist places a small amount of washed and prepared sperm into thick viscous media. This slows the sperm down, making it easier to observe and identify the ideal sperm based on their shape, motility and trajectory (direction).

Once our Embryologist has selected the most morphologically normal and vigorous sperm, they immobilise them by striking their tails with a glass injection needle. True story!

They then aspirate (suck up) a single sperm into the needle tail-first, ready to be injected into the egg.

Step 2: Injecting the sperm into the egg

First, our Embryologist places the egg in a customised dish under a microscope, moving it using advanced micro-manipulators. Next, they search for the ideal sperm for injection and immobilise this sperm and position it in the injection pipette. Then, they use a holding pipette to secure the mature egg in place. Finally, a thin, sharp glass micropipette – loaded with a single sperm – pushes first through the zona pellucida (the outer egg casing) and then the oolemma (the cell membrane of the egg) to enter the egg’s centre (the cytoplasm). The embryologist deposits the sperm ever so delicately into the centre of the egg.

In other words, our scientists do all of the work for the sperm – there’s no swimming or penetration of the egg involved. The only thing left for the sperm to do is to fertilise the egg.

Step 3: Fertilisation

After the ICSI procedure, we place the egg into our specialised culture incubators to assess for fertilisation ~17 hours later the next day, looking for signs or normal fertilisation, 2 pronuclear bodies known as ‘pronuclei’. These pronuclei are the genetic nucleus from the egg and sperm, so we need to see only two pronuclei, one from the egg and one from the sperm.

Common questions

Why would I consider ICSI over standard IVF?

ICSI can be a good option for men with fertility issues including low sperm count or poor sperm motility. If you don’t have one of the male fertility issues listed above, you’re probably better off using standard IVF rather than ICSI. There’s growing evidence to suggest that IVF success rates are actually higher when standard insemination techniques are used.

Are there any risks involved with ICSI?

ICSI is more invasive and requires more handling than standard IVF insemination techniques. So there is a chance that the egg may be damaged during the ICSI procedure. Current statistics indicate that damage post ICSI occurs in 5-10% of eggs ^[1]. Unfortunately, this could result in a non-viable egg.

If you think ICSI might be right for you, it’s a good idea to talk through the process with your fertility doctor. They’ll tailor a treatment plan to your individual circumstances to give you the very best chance of success.