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Prevention of Ovulation

IVF Step 1: Pre-stimulation

Taking over control of your pituitary gland.

A women’s reproductive cycle is controlled by the pituitary gland.  This tiny gland releases hormones (chemical messages) that tell the eggs when to grow and when to be released.   Hormones released from the pituitary gland stimulate the growth of follicles. A follicle is an immature egg that is surrounded by a sac of fluid that needs to grow and develop before the egg can be collected.  Once the pituitary senses that the follicle is mature enough, it will release a surge of hormone  which results in the follicle releasing the egg (ovulation).

Turning off the reproductive cycle in this way allows more control over the cycle.  If the pituitary gland is not “switched off” it may release hormones that will cause the follicles to release the eggs before they can be collected.     Better IVF pregnancy results are achieved by temporarily suppressing the release of reproductive hormones from the pituitary gland.

This can be achieved in two ways: either by switching off the pituitary gland for the whole cycle as in the long protocol (“down regulation”) or  switching off the pituitary gland just for a few days when spontaneous ovulation is more likelt, as in the short protocol.  The type of protocol used for your treatment will be discussed with you fully prior to your treatment cycle commencing.

Short Protocol:

The short protocol allows your own naturally occurring hormones to help with stimulation in the first five days of the cycle.   An injection of a drug called Cetrotide is then given from the sixth day of stimulation and will prevent the pituitary from releasing a surge of the hormone which may result in the release of the eggs prematurely.   Cetrotide is a gonadotrophin-releasing hormone (GnRH) antagonist (blocker) and will be taken daily until egg collection.

Long Protocol:

The drugs used to switch off your whole reproductive cycle are called gonadotrophin-releasing hormone agonists, or GnRH agonists for short.   They may include Buserelin (also called Suprecur) and Goserelin, a one-off injection – (also called Zoladex).   You will need to take the Buserelin every day and these are given by injection. The staff at the Unit will teach you how to administer this yourself.

Having your reproductive cycle turned off, tricks your body into thinking it is going through the menopause.   Because of this, you may experience symptoms similar to those of the menopause such as hot flushes, headaches, mood swings, dizziness, lack of concentration, dry mouth and vaginal soreness.  Don’t worry – this artificial menopause is only temporary and these symptoms will stop once you stop taking the drugs.

Mock Embryo Transfer

A mock embryo transfer will be carried out before your treatment begins. It is normally carried out when you come for your initial appointment (see step 1 – Prevention of Ovulation) or when you come for your first monitoring scan.

The mock embryo transfer allows us to assess how best to transfer your embryos back inside your womb.  We can determine which transfer catheter is best for you, which direction it should be guided through your cervix, and what depth inside your womb is appropriate.

Occasionally we are unable to get a transfer catheter through your cervix, in which case we will arrange for you to have your cervix dilated.  Even this may fail, and if this is the case we will arrange for you to have a hysteroscopy which will visualise the cervical canal under direct vision.

Page Last Modified: 12th July 2022


The Hull Andrology Unit has relocated its services from Hull Royal Infirmary to a new purpose built facility on the Hesslewood Office Park from Friday 1st October 2021.

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