IMSI / advanced sperm selection (Intracytoplasmic morphologic sperm injection (IMSI))

What is IMSI / advanced sperm selection?

IMSI stands for intracytoplasmic morphologic sperm injection. It is an optional extra — an 'add-on' — used during ICSI, the form of IVF where a single sperm is injected into an egg. With IMSI, the embryologist examines sperm under a much higher-powered microscope (magnifying over 6,000 times) to look at their shape in fine detail before choosing which to inject.

The idea is that picking the best-looking sperm might improve results. However, the Human Fertilisation and Embryology Authority (HFEA) — the UK fertility regulator — gives IMSI a 'grey' rating. This means it cannot rate IMSI as effective at improving the chance of having a baby, because there is not enough good-quality evidence. The HFEA notes that several trials have shown very little benefit, and the studies are of low quality.

IMSI is not a treatment in itself and it does not replace IVF or ICSI. It is an additional laboratory step that usually comes at an extra cost.

The HFEA's broader message is that, for most patients, standard cycles of proven fertility treatment work without paying for add-ons that have not been shown to help. This guide is here to help you ask the right questions before paying extra.

Types, options & approaches

There may be different ways to do this. The right approach depends on the clinical question and your circumstances.

Standard ICSI vs IMSI

HFEA ratings can change as evidence develops; always check the current rating on the HFEA website. This is general information, not advice for your case.

Preparing for your treatment

• Check the current HFEA rating for IMSI on the HFEA website before agreeing to it, as ratings are updated.
• Ask the clinic to explain, in writing, why IMSI is being recommended for you specifically and what difference they expect it to make.
• Ask whether your treatment would proceed perfectly well as standard ICSI without it.
• Ask what IMSI costs on top of your cycle, and whether that money might be better kept towards another standard cycle.
• Be cautious of any suggestion that IMSI is essential or that it guarantees a better result.
• Bring any previous treatment history, as that may be the reason it is being suggested.

What happens

IMSI happens in the laboratory on the day your eggs are fertilised, as part of an ICSI cycle. It does not involve an extra procedure on your body.

Instead of selecting sperm under a standard microscope, the embryologist uses much higher magnification to look closely at the shape of individual sperm, aiming to pick those that look most normal. The chosen sperm is then injected into the egg in the usual ICSI way.

From your point of view, the cycle feels the same as IVF/ICSI — stimulation, egg collection, fertilisation and embryo transfer. The only difference is the extra laboratory selection step, and the extra cost attached to it.

Is this treatment right for me?

A good consultation should explore whether it's the right choice for you now — including reasons to wait or consider something else.

Before you decide

Use this as a shared-decision checklist. The aim is not just “can this be done?”, but whether it is right for you, now, with the risks and alternatives clearly understood.

The main risk with IMSI is not physical — it is paying for something that has not been shown to improve your chance of having a baby. The HFEA's grey rating reflects weak, low-quality evidence. Ask the clinic to justify it for your specific situation, what it costs, and whether the same money would be better spent on a further standard cycle.

Published figures to discuss

There are no meaningful 'complication rates' for IMSI, because it is a laboratory selection step rather than a procedure performed on you. The relevant question is effectiveness, and on this the HFEA finds the evidence insufficient and of low quality. No reliable figure shows that IMSI improves the chance of a baby for most patients, so no success percentage is quoted here.

These are literature figures, not a personalised prediction. Your own risks and likely benefits depend on your circumstances, your health, and how your care is carried out and followed up.

What happens afterwards

There is no recovery, because IMSI is laboratory work, not a procedure on you. 'Afterwards' is simply the rest of your IVF/ICSI cycle and its outcome.

• No physical effects from IMSI itself
• The usual experience of an IVF/ICSI cycle around it
• Waiting for the pregnancy test result as with any cycle

Aftercare

• Follow the aftercare for your IVF/ICSI cycle, as IMSI adds nothing to it.
• Keep a clear record of which add-ons you paid for and why.
• If a cycle does not work, discuss honestly whether IMSI is worth repeating.
• Check the HFEA add-ons information again before any future cycle.
• Raise any concern about being pushed towards paid extras with the clinic or the HFEA.

• Current HFEA rating for IMSI checked
• Written reason it is recommended for you obtained
• Extra cost confirmed in writing
• Confirmed your cycle could proceed as standard ICSI
• Compared the cost against another standard cycle
• Asked how any benefit would be judged

⚠ Get urgent help if…

• Being told IMSI is essential or guarantees success — this is not supported by the evidence
• Pressure to decide quickly or pay extra without written information
• No clear, individual reason given for why you specifically need it
• Marketing claims that conflict with the HFEA's grey rating
• Add-on costs that are not itemised in your quote

Who to contact: your clinician, clinic or test provider first (keep their number to hand). For urgent advice when you can't reach them, call NHS 111. In an emergency, call 999.

General guidance — it doesn't replace the specific advice your specialist gives you.

Results & realistic expectations

Because IMSI is an add-on, its 'result' is simply the outcome of your IVF/ICSI cycle. The HFEA's position is that there is not enough good-quality evidence that IMSI improves the chance of having a baby for most patients, including for male-factor infertility. A cycle that works after IMSI cannot be assumed to have worked because of IMSI.

The most useful outcome of reading about IMSI is an informed decision: understanding that it is optional, unproven on current evidence, and an extra cost — so you can choose whether to spend on it or put resources towards proven treatment instead.

IMSI does not change your fertility or have any lasting effect — it is a one-off laboratory step within a single cycle. The HFEA rating may change over time as new evidence emerges, so it is worth re-checking before any future cycle.

Related tests, treatments or support

IMSI is only used alongside ICSI; it is not a standalone treatment. Some clinics offer several sperm-selection or embryo add-ons together. Bundling add-ons can increase cost without proven benefit, so each one should be justified on its own merits and against its own HFEA rating.

Follow-up & long-term care

There is no specific follow-up for IMSI beyond your normal IVF/ICSI review. At that review, it is reasonable to ask the embryologist what IMSI contributed, and to decide — with the HFEA rating in mind — whether to use it again.

Repeat, follow-on and what comes next

• If a cycle does not work, the honest question is whether IMSI added anything, given the weak evidence.
• HFEA ratings can change, so the decision should be revisited before any future cycle.
• Repeating an unproven add-on simply because it was used before is not a strong reason to continue.

Ask what happens if the result is unclear or needs repeating, and what is included if further tests or follow-up are needed.

What good aftercare looks like

• A clear, itemised record of which add-ons you paid for and why.
• An honest review of whether any add-on contributed to the outcome.
• A reminder to re-check the HFEA rating before any future cycle.
• A route to raise concerns about add-on selling with the clinic or HFEA.
• Decisions about future cycles led by your clinical needs, not by add-on sales.

What affects the cost

Costs vary a great deal between people and providers, and we don't publish prices. What matters is understanding what drives the cost and making sure your quote is complete. The main things that affect it:

• The extra laboratory fee charged for IMSI on top of the ICSI cycle
• Whether it is bundled with other add-ons that each add cost
• The base cost of the IVF/ICSI cycle it is added to
• The number of cycles in which you choose to use it
• Clinic-to-clinic variation in how add-ons are priced

• The IMSI fee itemised separately from the IVF/ICSI cycle
• Confirmation that the cycle could go ahead without IMSI
• What evidence the clinic relies on for recommending it to you
• Whether other add-ons are being added and their costs
• What happens to the fee if IMSI is not used on the day
• The total cost of the cycle with and without the add-on

On the NHS? IMSI is an optional add-on that the HFEA rates as having insufficient evidence of benefit, so it is generally offered as a private extra rather than as routine NHS treatment. Whether the underlying IVF/ICSI cycle itself is NHS-funded — and the criteria you would need to meet — is decided by local NHS or HSC commissioners and differs across England, Wales, Scotland and Northern Ireland, and can change over time. NICE sets the clinical recommendations for England, but it does not decide who gets funded; always confirm your current eligibility with the relevant NHS or HSC fertility service or clinic.

You're entitled to your total cost in writing — including reports, follow-up and what happens if the result is inconclusive — before you decide.

Consent traps and marketing red flags

These are not small details. They are often where patients lose choice, time to reflect, or realistic expectations.

Choosing a specialist safely

• Check the specialist is on the GMC Specialist Register for this area.
• Make sure they work at a CQC-registered service, and look for membership of the relevant Royal College or professional body.
• You're entitled to time to consider and to have your questions answered before you agree — the specialist who looks after you should explain it, not a salesperson.
• Be wary of pressure: time-limited offers or deposits taken before you've had time to think are red flags, not bargains.
• You're entitled to your total cost in writing — including any follow-up — before you decide.

How Vuemedics verifies every consultant →

Take this to your consultation. A good specialist will welcome every one of these.

• Why are you recommending IMSI for me specifically, rather than standard ICSI?
• What is the current HFEA rating for IMSI, and what does it mean?
• What exactly will IMSI cost on top of my cycle?
• Would my treatment proceed just as well without it?
• Could that money be better spent on another standard cycle?
• Are you on the GMC Specialist Register for this area, and which Royal College or professional body are you a member of?
• Will you be the specialist who carries out my treatment, and who looks after me afterwards?
• What are the risks for someone like me, and how often do your own patients have a problem or need it repeated or redone?
• What does a realistic result look like — and what can this treatment not achieve?
• What are my options, including waiting, doing nothing for now, or choosing a different approach?
• Can I have written information, results and aftercare instructions in a format I can use, including any accessibility or communication support I need?
• What is the total cost in writing, including any follow-ups, and how much time do I have to decide?

Find a verified specialist for imsi / advanced sperm selection

Every consultant is GMC-checked and independently reviewed. Search by postcode and distance, or switch to a map. Ordered by rating, relevance and recency — never by who pays.

How we made this page

Medically reviewed by a GMC-registered consultant. Written in plain English, checked against NHS, NICE, GMC and relevant Royal College / specialist-society guidance, and kept under review. No clinic paid to appear on this page, and we publish no pricing. This is general information to help you prepare — it is not a substitute for advice from your own clinician. How we review our guides →

Source hierarchy: UK regulator and NHS/NICE guidance first, then relevant Royal College or specialist-society guidance, then peer-reviewed evidence for procedure-specific figures where available.

Sources & standards: HFEA — Intracytoplasmic morphologic sperm injection (IMSI) HFEA — Treatment add-ons with limited evidence HFEA — Intracytoplasmic sperm injection (ICSI) HFEA — Choose a Fertility Clinic (verified success rates) British Fertility Society — Fertility treatment information NICE NG257 — fertility problems (clinical recommendations, England) NHS inform (Scotland) — infertility and access to treatment NHS Wales — specialist fertility services commissioning policy (CP38) Regional Fertility Centre, Belfast (Northern Ireland / HSC)

Reviews reflect patients' experience of care, not clinical outcomes. For procedure volumes and outcome data see PHIN.

Last medically reviewed 2026-09-21. Spotted something wrong or out of date? Report an error in this guide.