Intracytoplasmic Morphologically Selected Sperm Injection (IMSI) is an advanced laboratory procedure performed during IVF. It is an enhanced version of Intracytoplasmic Sperm Injection (ICSI), designed to improve sperm selection before fertilisation.
During conventional ICSI, embryologists select sperm using a microscope that magnifies the cells approximately 200 to 400 times. While this allows the identification of moving sperm suitable for injection, certain microscopic structural abnormalities may not be visible.
IMSI uses specialised optical equipment capable of magnifying sperm by more than 6,000 times, enabling embryologists to examine sperm in much greater detail. This higher magnification makes it easier to identify subtle abnormalities affecting the sperm head, nucleus, and overall morphology before selecting a sperm cell for injection into a mature egg.
The goal of IMSI is to improve sperm selection for patients whose fertility challenges may be linked to sperm quality, particularly in cases where conventional ICSI has not produced the desired results.
IMSI is not required for every IVF cycle. Instead, it is recommended for patients whose fertility history suggests that advanced sperm selection may improve treatment planning and fertilisation outcomes.
Your fertility specialist may recommend IMSI if:
Before recommending IMSI, your fertility specialist will review semen analysis results alongside the couple’s overall fertility evaluation to determine whether this advanced laboratory technique is likely to provide additional benefit.
Although IMSI follows many of the same steps as conventional IVF and ICSI, the sperm selection process is considerably more detailed.
Treatment begins with a comprehensive fertility assessment for both partners. This includes hormonal investigations, ultrasound evaluation where appropriate, and a detailed semen analysis to assess sperm count, motility, morphology, and overall reproductive health.
Depending on the findings, your fertility specialist may recommend IMSI as part of your personalised IVF treatment plan.
During IVF, the female partner undergoes ovarian stimulation to encourage the development of multiple mature eggs. Once the follicles have reached the appropriate stage of development, the eggs are collected using a minimally invasive procedure.
A semen sample is processed in the embryology laboratory before individual sperm cells are examined under ultra-high magnification.
Using specialised microscopy, embryologists carefully assess each sperm for subtle structural characteristics that cannot normally be seen using standard laboratory equipment. Sperm showing the most favourable morphology are selected for fertilisation.
Once the healthiest sperm has been selected, a single sperm is injected directly into each mature egg using the IMSI technique.
The fertilised eggs are then cultured in the laboratory while embryologists monitor embryo development over the following days.
The highest-quality embryo is selected for transfer into the uterus at the appropriate stage of development. Depending on the treatment plan, additional advanced techniques such as Laser Assisted Hatching, EmbryoGlue, or Preimplantation Genetic Testing (PGT) may also be considered where clinically appropriate.
Many patients wonder whether IMSI is the same as ICSI. Although both procedures involve injecting a single sperm directly into an egg, the major difference lies in how the sperm is selected.
With conventional ICSI, sperm are selected using standard laboratory magnification. This approach is highly effective for many patients and remains one of the most widely used fertility treatments for male factor infertility.
IMSI builds on the principles of ICSI by allowing embryologists to evaluate sperm under much higher magnification before selection. This additional level of detail may be beneficial for patients with severe sperm abnormalities, previous failed IVF cycles, or recurrent pregnancy loss where sperm quality may be contributing to treatment outcomes.
Your fertility specialist will recommend the most appropriate technique based on your individual diagnosis rather than using IMSI routinely for every patient.
For selected patients, IMSI offers several potential advantages over conventional sperm selection methods.
Potential benefits include:
Although IMSI may improve treatment outcomes for some patients, it is important to recognise that successful pregnancy depends on many additional factors, including egg quality, embryo development, uterine health, and maternal age.
Male infertility can result from a combination of factors, including reduced sperm count, abnormal sperm shape, poor motility, DNA damage, or difficulties with sperm production.
For this reason, IMSI is often considered alongside other advanced laboratory technologies designed to optimise sperm selection. Depending on your diagnosis, your fertility specialist may recommend complementary procedures such as Physiological Intracytoplasmic Sperm Injection (PICSI), Microfluidic Sperm Sorting, or Sperm Retrieval Procedures (TESA/PESA) when clinically appropriate.
By combining these technologies with a personalised IVF treatment plan, Nordica Fertility Centre provides comprehensive care for couples facing complex male fertility challenges.
IMSI may be recommended for men with poor sperm morphology, low sperm count, recurrent IVF failure, repeated miscarriage, or other forms of severe male factor infertility.
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