ICSI 101: Intracytoplasmic Sperm Injection

Oct 24, 2021 10:37am

What is ICSI?

ICSI (short for Intracytoplasmic Sperm Injection) is a procedure performed during IVF when a single sperm is injected into an egg.

Most often associated with male factor infertility, ICSI can be enormously helpful if sperm lacks mobility, motility, quality or is irregular in shape.

However, there are a number of other reasons why a couple might choose or be advised to pursue ICSI during their IVF treatment protocol. Another common reason? When there is a limited number of eggs to work with.

How does ICSI work?

  1. Prior to delivering a sperm sample, patients must abstain from sexual activity for several days.
  2. The female partner will undergo ovarian stimulation and retrieval.
  3. The male partner then produces a semen sample, typically by masturbation (or a thorough clinical retrieval method if medical complications prevent ejaculation).
  4. Clinicians perform a sperm analysis (see below for details) to determine the viability of the sample.
  5. The fertility clinic then prepares the semen sample by centrifuging (spinning) the sperm cells in a solution designed to separate live sperm from debris and dead sperm.
  6. Once the live sperm are extracted, the embryologist then picks up the single live sperm in a glass needle and injects it directly into the egg.
  7. With either traditional IVF or ICSI, once fertilization occurs, the fertilized egg (now called an embryo) grows in a laboratory for 1 to 5 days before it is transferred back into to the uterus.

Who is ICSI good for?

ICSI is often recommended in circumstances like:

  • Couples experiencing male-factor infertility, such as low sperm count or motility, which compromises the sperm’s ability to fertilize an egg
  • IVF cases with few eggs available
  • A male partner with blockage (which might occur following a failed vasectomy reversal, or from surgical scaring, among other reasons) in the male reproductive tract
  • If previous rounds of IVF resulted in no fertilized embryos, regardless of the reason
  • To increase fertilization rates when using in-vitro matured eggs or previously frozen eggs
  • Cases of unexplained infertility

Who should avoid ICSI?

Since ICSI can involve an additional cost compared to traditional IVF, ICSI isn’t right for everyone. With normal sperm, traditional IVF procedures can produce sufficient fertilization.

In addition, anyone with a family history of chromosomal abnormality may want to consider alternative methods instead of ICSI because the overall risk of having a baby with a chromosomal abnormality is four times the average risk in unassisted conception

Complications associated with sex chromosome abnormality include:

  • Increased risk of miscarriage
  • Heart problems for affected infants that may require surgery
  • Increased risk of behavior or learning disabilities
  • Increased risk of infertility in your children during their adulthood

On the other hand, maternal age associated chromosomal abnormalities (like Down’s syndrome) aren’t shown to increase in ICSI patients.

How does a semen analysis work?

Typically, semen analysis occurs prior to any infertility treatment, especially those involving ICSI. Semen analysis generally takes place immediately following sample preparation. During analysis a specialist examines a sample of semen under a microscope, noting the shape (morphology), activity (motility), and number (count) of sperm present in the sample.

What does a sperm analysis show?

The primary indicators of fertility examined during sperm analysis are:

  1. Sperm Count - The number of sperm present in a given sample.
  2. Mobility - Whether and how many of the sperm in a given sample can move effects male-factor fertility. Generally, more mobile sperm are more viable and more likely to fertilize an egg.
  3. Motility - Some samples may show highly active sperm, but if they just move side to side instead of “swimming” (aka, moving throughout the sample), this could indicate less healthy sperm. Motility measures whether (and how fast) the majority of sperm can “swim” forward.
  4. Morphology - The shape of the sperm can also indicate fertility levels. Normal sperm have a small, oblong “head” attached to a long, mobile “tail” that gradually narrows to a point.
  5. Quality - Overall sperm quality is determined by assessing all of the above factors, in addition to the following factors:
    • Vitality - Percent of sample consisting of live sperm.
    • pH level - Acid levels, which can affect the health of your sample.
    • Semen volume - Total of all substances produced in semen.
    • Sperm concentration -  Number of sperm per millimetre.
    • Liquefication - The time it takes for semen to change from thick, sticky substance to liquid.
    • White blood cells - If a sample contains white blood cells, it may signal the presence of infection or inflammation.

At-home sperm analysis—how do they work?

At-home sperm tests can be a logical first step for couples experiencing infertility. Currently, most men aren’t checked for infertility until couples have been trying to conceive for at least a year, so a home test may help find answers sooner. While at-home test kits are nothing short of spectacular and incredibly convenient, keep in mind that nothing compares to an actual in-person consultation with a registered reproductive endocrinologist and/or urologist. 

How to Test At Home

The procedure for conducting an at-home sperm analysis will vary based on which type of test you use. Multiple at-home male fertility test kits exist on the market today, and they provide a range of different information. While some may attempt a full sperm count, others simply confirm the presence or absence of sperm. Another option involves using a smartphone attachment to assess sperm motility. All of these give important information, but still lack the detail and reliability of an in-office test.

Generally speaking, at-home tests involve ejaculation into a sterile container, followed by pipetting a small amount of semen into a marked collection area and waiting a few minutes for results. However, each different kind of test will require a different procedure and will include its unique procedural instructions on the package.

How do in-office tests differ?

As discussed above, practitioners examine sperm more thoroughly than at-home kits can achieve by examining factors such as morphology, acidity, and vitality. The sterile technique used by fertility specialists also preserves the integrity of these tests and prevents faulty results and contamination.

Does ICSI guarantee IVF success?

Despite the possibility of increasing fertilization rates, additional complications may occur during or after the ICSI procedure:

  • The needle used to deliver the sperm can damage the egg.
  • Fertilized eggs may not develop into an embryo.
  • The embryo may stop growing at any point along the way.

Here’s the good news: 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.

What are the success rates of IVF with ICSI?

Fertility Rates

Low sperm quality decreases fertilization, and the data shows that ICSI can help improve fertilization rates for couples facing this particular fertility challenge. California State University, San Fransisco — the medical research university that pioneered the ICSI approach — reports that ICSI fertilizes 70% to 80% of eggs. This rate is similar to the fertilization rates seen in normal sperm.

Additionally, in 2016 The centers for disease control conducted a study of IVF outcomes from 1996-2012 and found that, “For cycles with a diagnosis of male factor infertility, the likelihood of cycle cancellation between egg retrieval and embryo transfer (a surrogate measure of failed fertilization) was markedly decreased for cycles where ICSI was used… confirming that ICSI increases the chances of fertilization for couples with male factor infertility.” This result bodes well for the potential efficacy of ICSI in treating male-factor infertility.

Birth Rates

Unfortunately ICSI did not perform as well in other measurements of fertility success. For example, even patients with male-factor fertility were not found to have increased live birth rates compared with conventional IVF. In fact “For cycles without male factor infertility, ICSI use was associated with decreased rates of implantation,” indicating that ICSI should only be used to address sperm-specific fertility complications. Other studies have found similar results. For one, a study in the National Library of Medicine concluded that routine ICSI use in all patients, regardless of the cause of infertility, doesn’t improve fertility.

Can ICSI damage the sperm?

In addition to the effectiveness rates discussed above, couples contemplating ICSI may want to consider the slight increase in birth defects. Compared to children conceived without reproductive assistance, congenital defects occur in an additional 1% of ICSI births.

The reason for this increase isn’t yet understood, but some research has investigated the possibility of internal sperm damage. ICSI has not been shown to have a significant impact on the vitality of living sperm, however more studies are needed to determine the prevalence of DNA damage occurring as a result of ICSI. Damaged DNA might account for some of the birth defects seen in ICSI treatment.

However, many practitioners assert that the increased presence of damaged DNA in ICSI patients comes as a result of the infertility itself, not the ICSI procedure because the chance of birth defects associated with ICSI is similar to IVF, and just slightly higher than in natural conception. In addition, some of the problems that cause infertility may be genetic and come from genetic differences in the father’s line. Thankfully, this risk is relatively small considering that annually such defects normally occur in 2% of all births. For many couples struggling with infertility, the pros far outweigh the risks when it comes to ICSI.

Should we do ICSI with our IVF?

Of course, every case of infertility has different factors to consider, and should involve collaboration with your fertility specialist(s). However, understanding the basic pros and cons could help guide your choice.


  • Increased fertilization gives you more chances to try and reach successful implantation and pregnancy.
  • Ensures the highest quality sperm is selected.
  • Similar rates of implantation, pregnancy, and live birth per embryo transfer.


  • Additional expense to IVF.
  • May not improve fertilization in non-male factor infertility.
  • Slightly higher risk of egg damage and/or sperm damage.