After your screening tests and Treatment Information Appointment (TIA) you will be ready to begin the treatment itself. By now, you will have received details of all the necessary medications you need and been allocated to one of two different drug protocols, the Long GnRH Agonist Protocol or the Short Antagonist Protocol. The Long Protocol otherwise known as “down regulation” makes your ovaries temporarily inactive which promotes easier management of your treatment cycle during stimulation by daily hormone injections. This protocol is used in women who have normal ovarian reserve. You will need an ultrasound scan to confirm that the down regulation has been successful. In the Short Protocol, there is no down regulation and it is reserved mainly for women who have poor ovarian reserve. It is also used sometimes in women who have high ovarian reserve as a means of reducing the risks of ovarian hyperstimulation.
In both protocols you will need daily Follicle Stimulating Hormone (FSH) injections to promote the development of multiple follicles in the ovaries. Regular ultrasound scans will help us see just how well your ovaries are responding to the injections, by counting and measuring the size of the developing follicles and the thickness of the endometrium (the inner lining of the womb). We aim to allow your follicles develop to about 18-20mm diameter and the endometrium to at least a thickness of 7mm-8mm.
Human chorionic gonadotropin (hCG): the late-night injection
Once your follicles and endometrium are at the optimum stage of development, you will be given an injection of Human Chorionic Gonadotropin. hCG is a hormone which will induce the ripening of your eggs so that we can collect them about 36 hours later, just a few hours before they are naturally released by your ovaries.
Why do we call it the late-night injection?
This is because the injection is usually given between 9pm and 1am; a time chosen to correlate directly to the exact time of your egg collection some 36 hours later.