Intracytoplasmic Sperm Injection (ICSI) Clinic

ICSI is a specialist technique in which a single sperm is injected into the centre of an egg. The technique is commonly used when the sperm to be used is not optimal, often because of low sperm count or motility (its ability to swim towards the egg). ICSI is also preferable for a number of reasons, for example combined with pre-implantation genetic diagnosis (PGD) or preimplantation genetic testing for aneuploidy (numerical chromosomal abnormality) (PGT-A) or when sperm DNA fragmentation is high.


How does ICSI work?

Fertility drugs are given to the female partner to stimulate the production of multiple eggs which are contained in follicles (fluid filled sacs) on the ovaries. Progress is monitored using ultrasound and blood tests.

When the leading follicle reaches 17-22mm, the final preparation for the egg collection is done. This involves a hormone injection of human chorionic gonadotrophin (hCG) or gonadotrophin releasing hormone agonist (GnRHa) or dual trigger (hCG and GnRHa), which is given approximately 37 hours before the egg collection. The hCG or (GnRHa) injection stimulates the eggs to mature.

The egg collection procedure is usually done using sedation. An ultrasound guided vaginal probe is used to locate the follicles and aspirate its contents. The eggs are then placed in culture in our embryology laboratory. It is difficult to determine the number of eggs that will be collected until the procedure. In rare cases, no eggs are collected.

In the laboratory, the embryologists will inject one sperm into each egg. In some cases, sperm may need to be surgically removed.

Once the embryos have developed to day 5 or 6 of development, known as the blastocyst stage, the embryologist will select one embryo to be transferred back to the womb during an embryo transfer procedure. It is a painless and quick procedure. The embryo(s) are loaded into a fine catheter and this is placed into the womb and the embryo(s) are expelled. After the embryo transfer, the patient can resume her usual activities.

Two weeks after the embryo transfer, a pregnancy test is performed, and CRGH should be informed of the result.


How long do ICSI embryos take to develop?

The day after the sperm is mixed with the egg, embryologists will look for signs of fertilisation. The following day they will check to see if the embryo has divided (cleaved). Embryos are then allowed to develop and monitored in the laboratory until day 5 or 6. By day 5 or 6, approximately 40-50%  of the embryos should reach the blastocyst stage. At CRGH, we carry out blastocyst embryo transfer. There is a risk that none of the embryos reach the blastocyst stage.

The embryologists monitor and grade the embryos very carefully. In the majority of cases, if the embryos have developed well we would recommend a single embryo to be transferred to reduce the risk of twins. If a blastocyst transfer is going to take place, we will only normally transfer one embryo in patients under 38 years.


What happens to embryos that are not transferred?

All good quality embryos that are not transferred will be frozen. CRGH has a very high pregnancy rate for frozen embryo transfers. This gives a very high chance of getting pregnant in a subsequent cycle without having to go through the whole IVF procedure again.


What are my chances of having a baby with ICSI?

An embryologist will examine your sperm under a microscope and decide whether ICSI could increase your chances of having a baby. The average number of eggs that get fertilised using ICSI is around 60-70%. There is a risk of failure to fertilise eggs.

You are more likely to become pregnant with twins or triplets if more than one embryo is transferred during the process. Your clinician and/or embryologist will recommend single embryo transfer (SET) if they consider it to be the best option for you.


Is ICSI for me?

We may recommend ICSI if:

  • The male partner has a very low sperm count
  • The male partner’s sperm has poor motility (not moving normally) or poor morphology (abnormal shape)
  • Previous failed fertilisation with insemination by IVF
  • Sperm needs to be collected surgically from the testicles or epididymis
  • You are using frozen sperm in your treatment which is not of optimum quality
  • You are undergoing pre-implantation genetic diagnosis or testing for aneuploidy.

Contact us

If you would like to book an appointment with one of our doctors you can:

  • Speak to the booking team on +44 (0)20 7837 2905  (Mon – Fri 8.30am – 6pm)
  • Email us on 
  • Visit our Appointments page, fill out the contact form and a member of the team will be in touch

IVF Packages With Access Fertility

IVF Packages With Access Fertility
CRGH is partnering with Access Fertility to offer a series of IVF programmes and packages. For more information please click below.

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