Overview
If you are researching fertility treatment, then you might have definitely encountered the term ICSI success rate a few times. This is one of the first issues couples need to clarify when beginning a treatment. Many patients don’t know that there is a tiny chip, smaller than a coin, which is revolutionising the process of sperm selection in ICSI. The chip doesn’t replace the expertise of embryologists and your lab team. It just provides them with a new approach to selecting healthy sperm, which positively affects the results of fertilisation and embryo development. In this article, we will find out more about ICSI itself, its process, what the chip does, and what determines success rates.
ICSI, or intracytoplasmic sperm injection, is a specialised form of IVF in which a single sperm is injected directly into an egg with the help of a fine glass needle. This procedure was developed for couples facing male fertility issues. Now, it is one of the most widely used techniques in fertility clinics.
In conventional IVF, thousands of sperm are introduced into a dish, where they fertilise an egg naturally. However, in ICSI, one selected sperm is injected directly into the egg by an embryologist. It helps overcome several natural barriers. The reasons for which ICSI is recommended include poor quality or quantity of sperm.
Here is how the procedure takes place:
Before trying to understand the technology, it is generally helpful to understand whatICSI success rate measures and why it can vary from one couple to another.
Success depends on several factors, including the woman's age, egg and sperm quality, embryo development, and lab conditions.
Maternal age is one of the strongest predictors of outcome. Younger women generally have a higher number of good-quality eggs. This improves the chances of successful fertilisation and a healthy pregnancy.
A small microfluidic chip, roughly the size of a coin, used purely for sperm selection before injection, has transformed ICSI.
The chip contains tiny channels filled with culture fluid. When sperm are placed at one end, only the healthiest, most active sperm are able to swim through the narrow channels to the collection side. Weaker or damaged sperm are left behind. There is no centrifugation or forceful handling.
Since only one sperm is used per egg in ICSI, choosing the right one is very important. Sperm with better motility and lower DNA damage can lead to improved fertilisation and embryo quality.
Traditional preparation methods, including density gradient centrifugation, involve spinning the sample at high speed. This can generate reactive oxygen species that damage sperm DNA. Microfluidic sperm selection avoids this step as it mimics the natural journey sperm make inside the female body.
The chip's real importance lies in the quality of the sperm it selects.
Only sperm capable of actively swimming through the narrow channels reach the collection chamber, which naturally helps filter out sperm with poor motility.
Because the chip avoids centrifugation, sperm are exposed to a lot less mechanical stress. A 2024 study published in the Human Reproduction journal found that microfluidic sperm sorting selected a subgroup of sperm with markedly better DNA integrity and fertilising potential compared to conventional preparation.
The chip is simple to use and produces consistent results between samples. This is quite helpful for embryologists when it comes to maintaining a standardised workflow across cycles.
Sperm selection has always been an important part of the ICSI journey.
A suitable sperm typically shows good motility, a normal shape, and minimal DNA fragmentation. All these factors are linked to better fertilisation outcomes.
Density gradient centrifugation and the swim-up method have long been the standard. Both are effective but rely on spinning or timed separation, which can stress the sperm sample.
Microfluidic chips select sperm based on natural swimming behaviour rather than physical force. Several studies suggest that it results in less DNA damage. A 2025 systematic review and meta-analysis published in the Andrologia journal reported improved fertilisation outcomes in a number of the studies it examined when microfluidic selection was used ahead of ICSI.
Every ICSI cycle follows a careful sequence inside the laboratory.
Eggs are checked for maturity, and the sperm sample is prepared. Sometimes this is done using the microfluidic chip and sometimes using conventional methods, depending on the case.
The embryologist identifies a single, healthy-looking sperm under high magnification for injection.
Using a fine glass needle, the embryologist injects the chosen sperm directly into the centre of the mature egg.
Eggs are checked the next day for signs of fertilisation, and embryos are monitored over the following days to assess their development.
ICSI is not needed by every couple undergoing fertility treatment. It is generally recommended in specific situations.
Low sperm count, poor motility, or abnormal sperm shape are among the most common reasons ICSI is recommended.
Couples who experienced low or failed fertilisation in a previous IVF cycle are often advised to try ICSI in their next attempt.
Technology plays an important role, but it works alongside several other factors.
Younger women with a healthy ovarian reserve typically respond better to stimulation and produce higher quality eggs.
Both partners' reproductive health contributes directly to fertilisation and embryo quality, regardless of which technique is used.
Not every fertilised egg develops into a transferable embryo, which is why embryo grading is such an important part of the process.
Air quality, temperature control, and incubator standards inside the lab all influence how well embryos develop after fertilisation.
A good outcome depends as much on the people running the lab as on the tools they use.
Even the most advanced chip cannot replace a trained embryologist's judgement. Skilled hands and careful observation remain central to every ICSI cycle.
Consistent protocols, calibrated equipment, and strict quality checks help ensure that every cycle is handled to the same high standard.
Tools such as the microfluidic chip are used alongside standardised procedures, so that patients receive dependable, evidence-based care.
Knowing what lies ahead can make the process feel far less overwhelming.
Your journey begins with tests for both partners, followed by a treatment plan tailored to your specific diagnosis.
After ovarian stimulation, eggs are retrieved, and ICSI is carried out on the same day, using freshly prepared sperm.
Fertilised eggs are cultured for a few days before the healthiest embryo, or embryos, are chosen for transfer.
A blood test roughly two weeks after transfer confirms whether the cycle has resulted in a pregnancy, followed by further monitoring in the early weeks.
The coin-sized microfluidic chip is a small addition with a meaningful purpose. By selecting sperm more gently and more precisely, it supports the work embryologists already do so well, without replacing their skill or judgement. Alongside age, egg quality and laboratory standards, sperm selection technology is one more piece of the puzzle that can improve your chances during an ICSI cycle. If you are considering ICSI, speak with your fertility specialist about which sperm selection method is right for your specific situation.