How a Karyotype Test Can Help Diagnose Infertility Issues

Author: Dr Irfana Koita  |  Published: 14 October 2026

A karyotype test for infertility checks the number and structure of your chromosomes using a blood sample. It can find genetic causes of infertility, repeated miscarriage, or failed IVF that routine hormone and semen tests do not show.

Chromosome changes are not common, but they matter. A 2025 study of 62,587 infertile couples found chromosomal abnormalities in 2.35% of individuals, and men were affected more often than women (BMC Genomics, 2025).

This guide explains what a karyotype test is, who should have one, how to read karyotype test results, and when a karyotype test before IVF can change your treatment plan.

Want to know if the test applies to you? Book a free advisory call with IVF Matters and speak to a fertility specialist.

What Is a Karyotype Test?

A karyotype test is a genetic test that looks at the size, shape, and number of chromosomes in your cells. Most people have 46 chromosomes arranged in 23 pairs (MedlinePlus, 2025).

For fertility, the sample is usually blood. The draw takes under five minutes and carries very little risk, apart from brief pain or bruising.

The lab then works through four steps:

1. The lab grows blood cells.

2. The lab stains the chromosomes so their banding patterns show.

3. They are photographed under a microscope.

4. A specialist arranges them into pairs by size and pattern, then checks for missing, extra, or rearranged pieces.

Genetic Causes of Infertility a Karyotype Can Find

A balanced translocation deserves special attention. A piece of one chromosome swaps places with another, but no genetic material is lost. The carrier is healthy, yet their eggs or sperm can pass on too much or too little material.

Because many carriers feel completely well, the first clue is often a pattern: repeated losses, failed cycles, or very low sperm counts with no clear cause.

Chromosome Abnormalities and Infertility: What 2025 Research Shows

The largest recent dataset comes from BMC Genomics, which reviewed 62,587 infertile couples having assisted reproduction between 2013 and 2022.

Klinefelter syndrome made up 84.7% of the numerical sex chromosome changes found in men. Translocations were the most common autosomal finding.

Who Needs Parental Karyotype Testing?

Parental karyotype testing means testing both partners, not only the person with the diagnosis. It is worth discussing if any of these apply:

• You have had recurrent miscarriages

• A partner has a very low sperm count or no sperm

• IVF has failed despite good embryos

• A woman has premature ovarian insufficiency

• A close relative has a chromosomal condition

• You are planning preimplantation genetic testing

The 2026 ASRM committee opinion says parental screening should be offered when a pregnancy loss shows an unbalanced translocation, or when the loss tissue was never tested. ESHRE and RCOG advise testing after an individual risk assessment rather than for everyone.

That is why a specialist review matters. A fertility consultant considers your age, number of losses, and previous results before recommending the test.

Example scenario: A couple has had three early miscarriages. The woman is 33, and her hormone tests are normal. A karyotype shows her partner carries a balanced translocation. He has no symptoms and never knew. The couple can now weigh PGT-SR against trying naturally, using real odds instead of guesswork.

Karyotype Test Before IVF: When It Changes Your Plan

You do not always need a karyotype test before IVF. It is most useful when your history points to a chromosomal cause.

If a balanced translocation is found, IVF with PGT-SR can help. PGT-SR screens embryos for the inherited rearrangement so only unaffected embryos are transferred. This differs from PGT-A testing, which screens for the wrong number of chromosomes.

Be realistic about the odds. The ASRM opinion notes that translocation carriers produce fewer chromosomally normal embryos, with rates of 17 to 22% depending on age. Couples needed about 4.5 blastocysts on average for a good chance of one normal embryo. It also reports that observational studies show live birth rates of around 70% without assisted reproduction, and that PGT-SR has not been proven better than waiting. Your consultant should discuss both routes.

In the UK, the HFEA licenses PGT-SR indications. NHS-funded cycles require a known variant, a 10% or higher chance of an affected pregnancy and a clinical genetics referral. Waits from first appointment to treatment can reach 8 to 18 months (NHS Genomics Education Programme, 2025).

Karyotype Test Results: How to Read Them

Your report lists a chromosome count, the sex chromosomes and any changes found. Keep the written report, not only a verbal summary, so you can share it with a genetic counsellor or another clinic if needed.

A normal result is reassuring but not a full genetic clearance. A 2025 study of balanced rearrangement carriers found an average karyotype resolution of about 9 megabases. Only 39% of the breakpoints found in embryos fell within the bands flagged on the blood karyotype (Molecular Genetics and Genomics, 2025).

Small deletions and single-gene changes need other tests, such as microarray or sequencing.

Questions worth asking when you get your report:

• Is my result balanced or unbalanced?

• Does my partner need testing too?

• Do I need microarray or sequencing as well?

• Should I see a genetic counsellor?

• Would PGT-SR change my treatment options?

Karyotype Test at IVF Matters: How It Works

IVF Matters offers a chromosome analysis for men. It is aimed at men planning preimplantation testing, men with failed IVF and men whose partners have had recurrent miscarriages.

1. Order. Buy the home kit (£399) or book a London walk-in appointment (£438).

2. Give a blood sample. Post the kit back, have it taken at the walk-in clinic, or use a Superdrug Nurse Clinic or pharmacy outside London. Local collection fees apply.

3. Lab analysis. The Doctors Laboratory analyses the sample. Results take up to 21 working days.

4. Receive results. They arrive through a secure patient portal.

5. Speak to a specialist. A complimentary call with Dr Irfana Koita explains the findings and possible treatment options.

You can use the service even if you are being treated at another clinic. Flexible payment plans are available.

Frequently Asked Questions

Is a Karyotype Test Painful?

It is a standard blood draw, so you may feel a brief pinch. Bruising at the site is the most common side effect. No fasting or preparation is needed.

Do I Need to Repeat a Karyotype Test?

Usually not. Your constitutional chromosomes do not change with age, so a clear result stays valid. A repeat is considered only if a lab flags a problem or the result is unclear.

Can Miscarried Tissue Be Tested?

Yes. Testing the pregnancy tissue shows whether a chromosome error in the embryo caused the loss. This often helps decide whether parental testing is needed.

Is a Karyotype Test Available on the NHS?

Access depends on your local service and clinical history. Ask your GP or NHS fertility clinic, particularly after recurrent miscarriage. Private testing is an option if you want results sooner.

How Is a Karyotype Different from Carrier Screening?

A karyotype looks at whole chromosomes for missing, extra or rearranged pieces. Carrier screening looks for specific single gene variants, such as those linked to cystic fibrosis. They answer different questions, and some couples have both.

Take the Next Step

If you have had failed IVF, recurrent miscarriage or a diagnosis of severe male factor infertility, a karyotype test may explain why. Book a free advisory call to talk through your history, or arrange a fertility consultation with Dr Koita.

Resources

• MedlinePlus: Karyotype Genetic Test: Definition, sample types, risks and result meanings (reviewed September 2025)

• BMC Genomics (2025): Karyotypic Analysis of 62,587 Han Chinese Infertile Couples: Prevalence of chromosomal abnormalities by sex and type

• Molecular Genetics and Genomics (2025): Accuracy and Real Resolution of Karyotyping: Limits of standard karyotype in balanced rearrangement carriers

• ASRM: Recurrent Pregnancy Loss: A Committee Opinion (2026): Guidance on parental karyotyping and PGT-SR

• NHS Genomics Education Programme: Preimplantation Genetic Testing (2025): UK eligibility, HFEA licensing and NHS waits

Explore More

• IVF Matters: Chromosome Analysis for Men: Order the test and book the follow-up call

• PGT-A Testing: What It Is and Why It Matters in IVF: How embryo screening works

• 5 Low Sperm Count Treatment Options for Men: Next steps after a male factor diagnosis

• Secondary Infertility: Why You May Struggle to Conceive Again: Other hidden causes of infertility

• How to Choose a Fertility Clinic in London: What to check before you commit