IMSI in IVF – differences to ICSI, advantages and disadvantages

By (gynecologist), (embryologist), (reproductive endocrinologist), (embryologist), (ob/gyn), (embryologist) and (biochemist).
Last Update: 05/16/2024

Intracytoplasmic Morphologically selected Sperm Injection (IMSI) is an improved type of ICSI (Intracytoplasmic Sperm Injection), techniques used in IVF cycles to increase the success rates.

These days, the IMSI procedure allows IVF with morphological selection of the spermatoa, before it is injected into the egg.

This state-of-the-art technique has many benefits for men with teratoozospermia, where the majority of sperm have an abnormal structure. By selecting the sperm with the best morphology, we increase the odds of pregnancy occuring.

What does IMSI consist of?

The ongoing improvements in the field of Assisted Reproductive Technology (ART) allow improved and innovative techniques to become available for IVF patients. All of these techniques are developed to increase the success rates of fertility treatments.

IMSI, sometimes also known as Super-ICSI, is one of these cutting-edge technologies. It uses a special lens for the microscope, to study the sperm under very high levels of magnification, greater than 6300x. This is a major advantage in comparison with ICSI, in which sperm are selected individually under a less powerful microscope at 400x magnification.

Thus, IMSI allows the embryologist to see the structure of spermatozoa in great detail, allowing them to detecting potential defects in the head, middle-piece, and/or tail.

According to the World Health Organization (WHO), for a sperm cell to have an excellent morphology, it must have the following characteristics:

  • Oval head
  • Straight or uncoiled tail
  • Fixed nucleus
  • Transparent color

Additionally, the sperm must have their acrosome intact and not contain vacuoles in their interior. You can find more information about spermatozao in this article: Sperm Cells, definition and structure.


Currently, the most widely used technique used in IVF cycles is ICSI, especially in cases of severe male infertility, or when the sperm count, motility, or morphology are affected.

However, ICSI is a subjective technique, as it is the specialist who chooses the sperm cells, following his personal criteria when observing the head, middle-piece, and tail.

Thanks to IMSI and the improvements that it brings to the process of examining and selecting sperm, we have seen the pregnancy success rates improve in cases of male infertility.

If you need to undergo IVF to become a mother, we recommend that you generate your Fertility Report now. In 3 simple steps, it will show you a list of clinics that fit your preferences and meet our strict quality criteria. Moreover, you will receive a report via email with useful tips to visit a fertility clinic for the first time.

When we select the sperm with the best morphology, the spermatozoa with poor morphology are ruled out depiste their potential ability to fertilize the egg. Poor morphology is associated with implantation failure and a higher risk of miscarriage. Therefore, motile spermatozoa without alterations and without vacuoles in the nucleus are chosen.

Another difference between ICSI and IMSI is the magnification at which the sperm is observed. In the case of ICSI, the microscope used is 400X. IMSI, on the other hand, offers an image magnified over 6000 times, allowing a much better evaluation of the sperm both externally and internally.

When is IMSI used?

Severe male factor infertility is one of the most common causes of not be able to get pregnant. It is estimated that 30% of infertility cases are due to a male factor. For example, if a man has low sperm quality a low sperm count, lazy or slow-moving sperm, or abnormal sperm morphology.

IMSI technique is particularly recommended when sperm morphology is the defect, a disorder that is known as teratozoospermia or teratospermia.

Selecting sperms with a good, normal morphology increases the pregnancy success rates in patients with infertility problems.

In addition, IMSI is used in the following cases:

It should be noted that IMSI is not used on a standard basis in IVF labs. It is used only in special cases, as the cost is considerably high and it does not necessarily increase the success rates in all cases.

Benefits of IMSI

The main benefit of IMSI is that it allows for an detailed visualization of sperm cells, thanks to magnification level of 6300X their normal size. This is an optical increase 15 times more powerful than in conventional IVF/ICSI cycles.

Furthermore, with IMSI live sperm can be selected in real time. As such, the use of dyes that could damage the sperm cells becomes unecessary.

Visualizing the sperms in such great detail not only allows us to detect potential head defects, but also in the middle-piece or neck, and the tail. The presence of such defects is associated with sperm DNA fragmentation.

In general, the IMSI technique has resulted in an increase in fertilization and pregnancy rates, whilst decreasing the miscarriage rate.

Disadvantages of IMSI

In spite of all the advantages that IMSI can add to your fertility treatment, it also has some disadvantages that one should consider, including:

  • It adds a considerable amount of extra time to the IVF procedure: about 1.5 to 5 hours.
  • Due to its elevated cost, it is not available in all IVF laboratories.

For all these reasons, IMSI is used only when sperm quality is very poor or in cases of repeated IVF or IVF with ICSI failure.

More research is necessary for this technique in order to prove its clinical efficacy and determine the cases where it should be applied.

Video about the IMSI technique

In the following video, Michelle Emblenton, a biochemist at inviTRA, tells us all the details about the IMSI technique:

FAQs from users

What are the advantages of IMSI?

By Mark P. Trolice M.D., F.A.C.O.G., F.A.C.S., F.A.C.E. (reproductive endocrinologist).

Selection of individual sperm under high magnification microscope, (intracytoplasmic morphologically selected sperm injection or IMSI), allows the use of the most apparantly optimal sperm according to shape (morphology) in men with the most severe male factor.

IMSI is considered for patients with recurrent implantation failure or spontaneous miscarriages (Lo Monte et al. 2013) due to the opinion the pregnancy failures were due to a sperm defect. However, recent studies have opposed this view by showing IMSI does not improve outcomes for men undergoing multiple IVF cycles. (Oliveira et al. 2011, Gatimel et al. 2016).

Is any special preparation required prior to IMSI?

By Dr Pilar Amador Bayo (ob/gyn).

A priori, IMSI does not require any special preparation prior to its performance. The process for IMSI is identical to ICSI, the only difference being the microscope used to select the sperm.
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What is the difference between IMSI and conventional ICSI?

By Carmen Ochoa Marieta M.D., Ph.D., M.Sc. (gynecologist).

Both are laboratory techniques that consist of injecting a spermatozoon into an egg. These spermatozoa are selected using morphological criteria, which are evaluated under the microscope.

In IMSI the microscope has 6000 magnification and in ICSI 400, so the fundamental difference between the two techniques lies in the sperm selection based on morphology.

Is IMSI possible with lazy sperm?

By Zaira Salvador B.Sc., M.Sc. (embryologist).

Yes, IMSI is possible with sperm samples that contain sluggish sperm, that is, samples with asthenozoospermia, as long as it is indicated for the reasons explained above.

The main purpose of IMSI is to select the sperm cells with the best morphology only. To select sperms with progressive motility conventional ICSI is sufficient since IMSI would not add any benefits.

How is IMSI performed?

By Zaira Salvador B.Sc., M.Sc. (embryologist).

The IMSI procedure is the same as in ICSI cycles. First, the sperm sample is processed in the lab, and the pellet is resuspended at the adequate concentration. The only difference between IMSI and ICSI is the microscope used to select the sperms morphologically with IMSI. This type of microscope is based on the MSOME technology (Motile Sperm Organelle Morphology Examination), which is equipped with a digital imager.

Once the embryologist selects the best sperms, they are transferred to the ICSI plate and taken to a conventional microinjector to fertilize the eggs.

What is special about IMSI?

By Rebeca Reus BSc, MSc (embryologist).

IMSI stands for intracytoplasmic morphologically selected sperm injection. This is an ICSI in which the sperm to be microinjected has been carefully selected based on its morphology. In order to select the sperm, ICSI is performed under a high magnification microscope that allows the morphological qualities of the sperm to be seen in detail.

Therefore, IMSI is an ICSI performed under a 6300 magnification microscope instead of the usual 400 magnification of ICSI.

Why is IMSI such a slow technique?

By Zaira Salvador B.Sc., M.Sc. (embryologist).

Because it is a very laborious technique that can be only by conducted by highly trained professionals. It often requires two embryologists to work simultaneously in order to reduce the duration of the process and perform it more objectively.

Moreover, due to the use of a more powerful microscope, finding sperm cells under the microscope becomes a difficult task, making it a technically challenging technique.

We have mentioned teratozoospermia as the main indication for the use of IMSI. To get a deeper insight on this sperm disorder, we recommend visiting the following post: What Is Teratozoospermia? – Causes, Pregnancy Rate & Treatment.

According to the WHO, a semen analysis is the most useful tool when it comes to evaluating male fertility, as it can detect potential sperm disorders. Learn more about sperm analysis here: What Is a Semen Analysis Report? – Purpose, Preparation & Cost.

Today, ICSI is the most widely used technique in IVF labs. You can get more information on this by clicking the following link: What Is ICSI Technique? – Process, Success Rates & Cost.

We make a great effort to provide you with the highest quality information.

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Arief Boediono, Nining Handayani, Henny Natalya Sari, Nuraeni Yusup, Wahyu Indrasari, Arie A Polim, Ivan Sini. Morphokinetics of embryos after IMSI versus ICSI in couples with sub-optimal sperm quality: A time-lapse study. Andrologia. 2021 May;53(4):e14002. doi: 10.1111/and.14002. Epub 2021 Feb 19.

Bartoov B, Berkovitz A, Eltes F, Kogosovsky A, YagodaA, Lederman H, et al. Pregnancy rates are higher with intracytoplasmic morphologically selected sperm injection than with conventional intracytoplasmic injection. Fertility and Sterility 2003;80(6):1413–9. [PUBMED: 14667877]

Berkovitz A, Eltes F, Yaari S, Katz N, Barr I, Fishman A, et al. The morphological normalcy of the sperm nucleus and pregnancy rate of intracytoplasmic injection with morphologically selected sperm.Human Reproduction2005;20(1):185–90. [PUBMED: 15471930]

Berkovitz A, Eltes F, Lederman H, Peer S, Ellenbogen A,Feldberg B, et al. How to improve IVF-ICSI outcome by sperm selection.Reproductive Biomedicine Online2006;12(5):634–8. [PUBMED: 16790113]

Cassuto NG, Hazout A, Benifla JL, Balet R, Larue L, Viot G. Decreasing birth defect in children by using high magnification selected spermatozoon injection. Fertility and Sterility 2011;1:S85.

Esmat Mangoli, Mohammad Ali Khalili, Ali Reza Talebi, Seyed Mehdi Kalantar, Fatemeh Montazeri, Azam Agharahimi, Bryan J Woodward. Association between early embryo morphokinetics plus transcript levels of sperm apoptotic genes and clinical outcomes in IMSI and ICSI cycles of male factor patients. J Assist Reprod Genet. 2020 Oct;37(10):2555-2567.

Felipe Dieamant, Claudia G Petersen, Laura D Vagnini, Adriana Renzi, Bruna Petersen, Fabiana Massaro, Camila Zamara, Andreia Nicoletti, Juliana Ricci 1, Antonio H Oliani, João Batista A Oliveira, José G Franco. Impact of Intracytoplasmic Morphologically Selected Sperm Injection (IMSI) on Birth Defects: A Systematic Review and Meta-Analysis. JBRA Assist Reprod. 2021 Jul 21;25(3):466-472. doi: 10.5935/1518-0557.20210030.

Oliveira JBA, Cavagna M, Petersen CG, Mauri AL, Massaro FC, Silva LFI, et al. Pregnancy outcomes in women with repeated implantation failures after intracytoplasmic morphologically selected sperm injection(IMSI).Reproductive Biology and Endocrinology2011;9:99.[PUBMED: 21781299]

Teixeira DM, Barbosa MAP, Ferriani RA, Navarro PA, Raine-Fenning N, Nastri CO, Martins WP.Regular (ICSI) versus ultra-high magnification (IMSI) sperm selection for assisted reproduction.Cochrane Database of Systematic Reviews2013, Issue 7. Art. No.: CD010167.

FAQs from users: 'What are the advantages of IMSI?', 'Is any special preparation required prior to IMSI?', 'What is the difference between IMSI and conventional ICSI?', 'What is Intracytoplasmic Morphologically selected Sperm Injection (IMSI)?', 'Is IMSI possible with lazy sperm?', 'When is IMSI used in IVF?', 'How is IMSI performed?', 'What are the advantages and disadvantages of IMSI?', 'What is special about IMSI?', 'Why is IMSI such a slow technique?', 'How is IMSI performed?' and 'Why is IMSI such a lengthy and costly technique?'.

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Authors and contributors

 Carmen Ochoa Marieta
Carmen Ochoa Marieta
M.D., Ph.D., M.Sc.
Bachelor's Degree in Medicine from the Basque Country University. PhD in Medicine & Surgery from the University of Murcia. Currently, she is the director of the Assisted Reproduction Unit of Centro de Estudios para la Reproducción (CER SANTANDER) in Santander, Spain, as well as the director of the Diagnostic Unit of Human Assisted Reproduction in Bilbao. More information about Carmen Ochoa Marieta
License: 484805626
 José Antonio Sánchez Férez
José Antonio Sánchez Férez
Bachelor's Degree in Biology from the University of Murcia. Vast experience as an embryologist, biologist, and researcher. Currently, he works as a Clinical Embryologist at Instituto Murciano de Fertilidad (IMFER). More information about José Antonio Sánchez Férez
 Mark P. Trolice
Mark P. Trolice
M.D., F.A.C.O.G., F.A.C.S., F.A.C.E.
Reproductive Endocrinologist
Mark P. Trolice is the Director of Fertility CARE – The IVF Center and Clinical Associate Professor in the Department of Obstetrics & Gynecology (OB/GYN) at the University of Central Florida College of Medicine. He is Board-certified in REI and OB/GYN, and maintains annual recertification. His colleagues select him as Top Doctor in America® annually, one among the top 5% of doctors in the U.S. More information about Mark P. Trolice
License: ME 78893
 Marta Barranquero Gómez
Marta Barranquero Gómez
B.Sc., M.Sc.
Graduated in Biochemistry and Biomedical Sciences by the University of Valencia (UV) and specialized in Assisted Reproduction by the University of Alcalá de Henares (UAH) in collaboration with Ginefiv and in Clinical Genetics by the University of Alcalá de Henares (UAH). More information about Marta Barranquero Gómez
License: 3316-CV
Dr Pilar Amador Bayo
Dr Pilar Amador Bayo
Pilar Amador Bayo studied Medicine at the University of Zaragoza and specialized in Obstetrics and Gynecology at the Jaén Hospital Complex. Currebtly, Dr. Amador Bayo is a gynecologist at Next Fertility Sevilla, formerly known as IMER Sevilla. More information about Dr Pilar Amador Bayo
 Zaira Salvador
Zaira Salvador
B.Sc., M.Sc.
Bachelor's Degree in Biotechnology from the Technical University of Valencia (UPV). Biotechnology Degree from the National University of Ireland en Galway (NUIG) and embryologist specializing in Assisted Reproduction, with a Master's Degree in Biotechnology of Human Reproduction from the University of Valencia (UV) and the Valencian Infertility Institute (IVI) More information about Zaira Salvador
License: 3185-CV
Adapted into english by:
 Michelle Lorraine Embleton
Michelle Lorraine Embleton
B.Sc. Ph.D.
PhD in Biochemistry, University of Bristol, UK, specialising in DNA : protein intereactions. BSc honours degree in Molecular Biology, Univerisity of Bristol. Translation and editing of scientific and medical literature.
More information about Michelle Lorraine Embleton

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