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Xambika patients

You deserve more than hope. You deserve insight and answers.

If you have experienced implantation failure or miscarriage, you know how frustrating it can be to have questions without clear answers. The PRELI test was developed to help uncover whether a hidden factor is involved: your womb lining.

Understanding your womb lining. Empowering your fertility journey.

Implantation failure and miscarriage can be linked to the embryo, the womb lining, or both. The PRELI test helps your doctor understand whether the womb lining may be playing a role. It provides insight before your next pregnancy and can help inform whether treatment to support the womb lining may be considered.

What is the PRELI test?

The PRELI test examines the health of your womb lining (endometrium) by measuring how well it prepares for implantation and pregnancy each cycle. It looks at a key biological process, called decidual reaction, which:

  • Helps an embryo to implant; and 
  • Develops the endometrium to support a full-term pregnancy. 

In addition, the test also looks at molecular timing, immune readiness, and infection.

Research has shown that, in some women, recurring molecular abnormalities in the endometrium may contribute to implantation failure or miscarriage, even when embryos appear healthy.

The PRELI test helps identify whether your endometrium shows signs of these abnormalities, so your doctor can better understand what may be happening before pregnancy begins.

  • Looks at the womb lining, not the embryo 
  • Based on over 20 years of academic research 
  • Provides insights to support personalised decision-making by your doctor 
  • Used as part of a broader fertility assessment, not as a standalone answer
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How does the test work?

1
The PRELI test involves a small biopsy of the womb lining, taken by your healthcare professional at a specific time in your cycle.
2
The sample is analysed in a specialised Xambika laboratory using advanced molecular techniques.
3
The results are shared with your clinician, who will discuss with you what they may mean for your care and possible next steps.
4
Your clinic will guide you through the timing, procedure, and any questions you may have.

Where can I get the PRELI test?

The PRELI test will become available in the UK in Spring 2026 through a network of fertility clinics and specialists.

Keep an eye on this website for more details.

If your clinic is not listed at that time, you may wish to discuss the PRELI test with your fertility specialist directly.

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Frequently Asked Questions

Q: What is the PRELI test? Xambika’s PRELI test examines the health of your womb lining (endometrium) by measuring how well it prepares for pregnancy each cycle. It looks at the key biological process (decidual reaction) that helps an embryo implant and develop the endometrium to support a full-term pregnancy. In addition, the test also looks at molecular timing, immune readiness, and infection.
Q: Why is the womb lining so important? A healthy womb lining is essential for allowing the embryo to implant, helping the placenta grow and supporting the pregnancy. Recent research shows that problems in this process can cause miscarriage or failed implantation, even when the embryo is healthy.
Q: What can the PRELI test tell me? Xambika’s PRELI test shows whether your womb lining response is normal, too strong (which may prevent implantation), or weakened (which may allow implantation but lead to miscarriage). It can also show whether timing is off, whether your immune cells are balanced, and whether there are signs of a hidden infection.
Q: Who is the PRELI test for? Patients who have experienced miscarriage or implantation failure.
Q: What happens during the PRELI test? The PRELI test involves a small biopsy of the womb lining, taken by your healthcare professional at a specific time in your cycle. The sample is analysed in a specialised laboratory using advanced molecular techniques. The results are shared with your clinician, who will discuss what they may mean for your care and possible next steps. Your clinic will guide you through the timing, procedure, and any questions you may have.
Q: Is it painful? Most people describe the biopsy as feeling like strong period cramps that last briefly.
Q: When in my cycle is the sample taken? 6-10 days after a positive ovulation test (peak day) in a natural cycle or a modified natural cycle with progesterone support, or 6-10 days after starting progesterone in an artificial/medicated cycle.
Q: Will I get treatment after the PRELI test? Based on the test results, your doctor might suggest a treatment or intervention, such as medications to strengthen the lining, adjust inflammation, treat infection, or optimise timing. The goal is to help you enter your next pregnancy attempt with the best possible conditions for success.
Q: Will the PRELI test delay my fertility treatment? No. It is usually completed in one cycle and helps avoid repeated unsuccessful attempts.
Q: Is this the same as other tests I may have heard of? No. Most of those tests each look at one factor. Xambika’s PRELI test looks at several major factors at once, providing a clearer and more complete picture of your womb lining. It’s also the only test that looks at the ‘dynamic decidual reaction’ which prepares the womb lining for pregnancy each month. The decidual reaction transforms the womb lining into a supportive tissue for the embryo to implant, and -when normal- progresses into a stable environment that supports a healthy pregnancy.
Q: Can the PRELI test explain my miscarriages? Yes. Research shows that many miscarriages are linked to a womb lining that does not prepare properly—even when embryos are healthy. The PRELI test helps identify whether this applies to you.
Q: How accurate is the PRELI test? Xambika’s PRELI test is based on over 20 years of research and one of the world’s largest studies on miscarriage and womb lining health by Professor Brosens and his team.
Q: Does the PRELI test guarantee a successful pregnancy? No test can guarantee success, but the PRELI test gives you and your doctor detailed insights into the endometrium, which can help inform a personalised treatment plan for the next steps in your fertility journey if the endometrium played a role in your miscarriage or implantation failure.
Q: How long will results take? We aim to provide your PRELI test results to your physician within five working days after your biopsy reaches our laboratory. Your doctor will review the results with you and discuss next steps. 
Q: Can I use the PRELI test if I’m not doing IVF? Yes. You can also use it before natural conception attempts.
Q: Where can I get the PRELI test? Xambika’s PRELI test can be ordered and carried out by any fertility doctor, IVF clinic, or OBGYN. On our website [include link once available], you’ll find a list of clinics that currently offer the test. If your clinic is not yet included, you can simply discuss it with your healthcare provider. Most clinics can order the test directly. You may also choose to contact one of our partner clinics listed on the website.
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Still have questions?

Most questions about the PRELI test are best discussed with your fertility specialist, who understands your medical history and treatment plan.

If you have reviewed the information above and still have a general question about PRELI, you may contact our team using the form.