The Patient's Guide to Embryology

A closer look at the IVF process

Step 1 – Get referred by your GP

Step 2 – Get a diagnosis

Step 3 – Have a consultation with a specialist

Step 4 – Start treatment

Step 5 – Collect and fertilise eggs

Step 6 – Grow embryos

Step 7 – Embryo transfer and freezing

Step 1

Get Referred by Your Doctor

Couples are usually referred for fertility investigations by their GP after 12 months of trying to have a baby without success. This can be sooner if there is a known fertility issue such as problems with the menstrual cycle or a genetic condition that affects the reproductive system. It may also be longer if the doctor thinks you have a good chance of getting pregnant naturally, for example if you weren’t having sex frequently enough or if lifestyle changes would help.

Step 2

Get a Diagnosis

You will need to have some investigations to figure out what might be the cause of your problems. Around 15% of couples won’t have any clear reason why they are struggling to get pregnant and are diagnosed with ‘unexplained infertility’.

Men will need to produce a semen sample which will be analysed to give an idea of sperm number and quality. Men may also be offered a physical examination or a blood test to check hormone levels. Women will usually have an ultrasound scan of the uterus and ovaries to look at the structure and to check for the number of follicles which are sacs of fluid in the ovary that contain an egg. This will need to be a transvaginal scan where the ultrasound probe is placed inside the vagina. Women will also have a blood test to check for hormone levels that can indicate how well the ovaries are working. Pay close attention to the results of these tests because they can give you an idea of how fertile you are and how you might respond to your IVF treatment.

Step 3

Have a Consultation with a Specialist

A specialist fertility doctor will review your test results and take your medical history to decide on the best course of action. They will give you a prescription for IVF drugs and a protocol to follow.

There will also be lots of consent forms to sign. You can start thinking in advance about some of the decisions you will need to make such as:

  • Who will be the legal parents of the baby?
  • How long do I want my extra embryos to stay in storage?
  • Do I want unused eggs/sperm and embryos to be used for training or research?

Step 4

Start Treatment

You will usually start taking your drugs on the first day of your period when it arrives and there are three phases:

  1. Stop the ovaries functioning normally

The first drugs you need to take stop the production of a hormone called GnRH from the brain. This stops normal activity in the ovary and gives control over how and when the eggs grow. Essentially it creates an artificial, reversible menopause.

  1. Grow eggs in the ovaries

The second set of drugs causes the ovaries to grow multiple eggs simultaneously. These are daily injections which you will take while also having ultrasound scans to check on the progress by looking at the size of fluid-filled sacs (follicles) which contain the eggs. Once the follicles are the ideal size, your egg collection procedure will be planned.

  1. Trigger the eggs to mature

The final drug is a single injection which must be taken exactly 36 hours before the time of your procedure. This causes the eggs to mature through the final stages of growth so they are ready for fertilisation in the lab. Less than 36 hours and the eggs are more likely to be immature, more than 36 hours and the eggs may be ovulated into the fallopian tubes and lost.

Step 5

Collect and Fertilize the Eggs

Eggs are collected from the ovaries in a simple procedure where a needle is used to puncture the wall of the vagina and drain the fluid from the follicles on the ovaries. The aim is to collect one egg from each large follicle. This will usually be done under sedation or local anaesthetic.

The eggs are checked for maturity in the lab and only mature eggs can be fertilized. Usually around 80% are at this correct stage. Sometimes it is possible to help the eggs finish maturing after they have been removed from the ovaries but this is not done in every IVF lab.

The sperm will be prepared at the same time the eggs are collected and they will be combined to achieve fertilization using either traditional IVF or ICSI.

Step 6

Grow Embryos

Typically around 70% of mature eggs fertilize successfully. All of the fertilised eggs are grown into embryos, usually for 5-6 days when they reach a stage known as the blastocyst. Not all embryos reach the blastocyst stage and the quality of the embryos can vary significantly. You can expect roughly 40% of fertilized eggs to reach the blastocyst stage.

Step 7

Embryo Transfer and Freezing

The best quality embryo (or embryos) can be transferred into the uterus where hopefully it will implant and make a healthy, successful pregnancy. If there are any surplus good quality embryos, these can be frozen for future use.

Embryos that haven’t developed into blastocysts by day 7 are not viable and can’t be used any further. 

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