Our frequently asked questions and a glossary of terms


Preimplantation genetic diagnosis

We have provided a glossary (PDF 11Kb) to explain any words used in this section that you might not know.

How much does PGD cost?

You may be entitled to NHS funded treatment. If you are not eligible for NHS funding then we would be happy to treat you as a 'self funded' patient. See more information on the cost of self funding.

How accurate is PGD?

The accuracy of PGD will vary but for most couples it will be more than 99% accurate. The risks will depend upon the condition for which we are offering PGD and your individual test results. Depending on what test is being used, couples may receive a detailed report describing the accuracy of their test before going ahead with PGD depending what test is being used.

How long does the process take?

Once you start a PGD treatment cycle, the process will take about nine weeks to reach embryo biopsy. Please see the treatment cycle pages for the details. The most time consuming part is the preparation before starting a PGD cycle. As we need to do laboratory testing, sometimes apply for a licence or funding and make sure that we have prepared you physically for PGD, it is likely to take six-12 months before starting treatment, please see timeline for details.

How do I get referred?

To organise an appointment you will need to be referred by your local clinical geneticists or genetic counsellor. Please contact them directly regarding this and they will be happy to help. Our centre liaises closely with all UK genetic centres. See our starting PGD treatment for further details.

Do you treat patients from overseas?

We can offer PGD treatment to patients resident in the UK who are entitled to NHS treatment and couples from the Republic of Ireland. We may be able to consider requests to treat couples from overseas.

Does PGD affect the babies born?

PGD is still a relatively new technique. Several studies looking at children born following the procedure have concluded that there do not appear to be any major side-effects to the treatment. The incidence of abnormality is similar to that seen in other forms of assisted reproduction (4-5%). The number of babies and childrenreviewed internationally remains small.

What is assisted reproductive technology?

Assisted reproductive technology (ART) is where conception is aided by the use of medical technology such as pre-implantation genetic diagnosis (PGD) or in-vitro fertilisation (IVF).

Why is assisted conception needed for PGD?

Usually each month, an egg develops in one of the ovaries in a small sac of fluid called a follicle. The egg is released from the ovary and passes down one of the fallopian tubes, which are attached to the uterus. For a pregnancy to occur, sperm, which has been deposited in the vagina during intercourse, has to swim towards the egg in the fallopian tube. This is where fertilisation normally occurs.

The fertilised egg begins to divide as it travels through the fallopian tube towards the uterus. After about five days, the fertilised egg (embryo) hatches out of its outer coating (zona pellucida) and buries itself in the thick lining of the uterus where it begins to grow (the process of implantation). Rarely, an embryo implants in the fallopian tube. This is called an ectopic pregnancy.


We know that a number of your embryos are likely to be affected by the altered gene or chromosome abnormality. Therefore, we need to create a large number of embryos for the best chances of success in a PGD cycle. It is important that we start by obtaining a good number of eggs from a woman. This means that we artificially take control and alter a normal menstrual cycle.

What is PGS?

The term PGS (pre-implantation genetic screening) relates to a treatment used in conjunction with fertility treatment. It is not used for couples with a known genetic condition but is believed by some health professionals to increase the success rate of fertility treatment. The British Fertility Society has made a recent statement indicating that there is no conclusive evidence that PGS is beneficial and indeed some papers have shown that it may actually reduce the chance of success. Until large studies known as randomised control trials have been completed, PGS is not a service that we will consider offering.  


Contact us

Genetics enquiries and potential patients

Tel: 020 7188 1392
Email: pgdgenetics

Email: gst-tr.

Assisted Conception Unit (ACU) enquiries and current patients

Tel: 020 7188 2300
Email: IVF.PGD@