In order for a pregnancy to occur naturally the ovary releases an egg at ovulation which travels through the Fallopian tube where it meets the sperm and is fertilised. The fertilised egg enters the uterine cavity where it implants in the thickened lining of the uterus (the endometrium). In IVF treatment, the ovaries are stimulated to produce a number of eggs which are collected and mixed with sperm in the laboratory, allowing fertilisation to occur. The developing embryos are monitored closely and the healthiest embryos are then transferred into the uterus to allow implantation to occur.
Couples who may require IVF treatment may present with some of the following issues:
- Blocked fallopian tubes
- Poor ovarian reserve
- Unsuccessful IUI treatment
- Male factor infertility (often require ICSI)
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The IVF Treatment Cycle
There are several stages to an IVF treatment cycle. The average treatment cycle takes approximately eight weeks from the start of medications until a pregnancy test is taken.
First Stage: Pituitary Gland Suppression (‘Down-Regulation’)
In the most commonly used treatment protocol (‘long protocol’) the woman takes the combined oral contraceptive pill for approximately three weeks, starting with the first day of her period. This prevents the development of ovarian cysts as the treatment cycle begins.
Following this she commences a daily injection of gonadotrophin-releasing hormone (GnRH) analogue (Buserelin) which temporarily makes the pituitary gland incapable of releasing LH, thus preventing early ovulation.
Some patients experience minor side effects such as hot flushes while taking Buserelin.
Second Stage: Superovulation
During this stage the ovaries are stimulated to produce a large number of mature eggs. A daily injection of FSH+/- LH is commenced which stimulates the growth of several follicles, generally between 10 and 20, each containing an egg.
Trans-vaginal ultrasound scans are used to monitor the growth of the follicles. When the follicles reach an appropriate size (approximately 18mm) the GnRH analogue and FSH+/- LH injections are stopped and an injection of hCG (human Chorionic Gonadotrophin) is given to bring about final maturation of the eggs.
Third Stage: Egg Collection
Approximately 36 hours after the hCG injection, egg collection takes place and usually occurs in the morning. This is a minor procedure carried out under light sedation in our theatre at Cork Fertility. A slim trans-vaginal ultrasound probe is used to guide a fine needle through the vaginal wall in order to drain the fluid from each follicle (which should contain an egg). The procedure takes 15-30 minutes patients are allowed home approximately one hour after the procedure.
Fourth Stage: Insemination
On the morning of the egg collection the male partner is asked to produce a semen sample which is then washed and prepared. The best quality sperm are then mixed with the retrieved eggs in a petri-dish containing a high quality culture medium and placed in an incubator to allow fertilisation to occur.
The embryologist examines the eggs microscopically the following day to check for fertilisation. Under normal circumstances 80% of eggs will fertilise.
Fifth Stage: Embryo Culture and Transfer
The embryologists examine each fertilised egg daily to monitor progress and development and communicate with the couple by telephone to keep them updated during this time. The best quality embryos are graded based on microscopic appearance and one or two of the best quality embryos are selected for transfer into the uterus. Embryo transfer usually occurs three or five days after egg collection.
Embryo transfer is a simple out-patient procedure and no sedation is necessary. Similar to a smear test, a speculum is used to visualise the cervix. The embryos are picked up, in a tiny drop of culture fluid, in the tip of a fine plastic transfer catheter. This catheter is passed carefully through the cervical canal and into the uterine cavity where the embryos are deposited.
The number of embryos transferred depends on the apparent quality of the embryos and the female partner’s age. The final decision as to whether to transfer one, two or (rarely) three embryos is made by the doctor and embryologist who try to maximise the chance of conception but minimise the chance of a multiple pregnancy (e.g. triplets).
Sixth Stage: Luteal Phase and Pregnancy Test
Eighteen days after egg collection the couple should perform a urine pregnancy test and inform the clinic of the result. The time between embryo transfer and pregnancy test is often the most stressful period of the treatment cycle.
In the week following embryo transfer, patients should avoid vigorous physical activity, swimming, baths and sexual intercourse. A number of medications are prescribed to help support the implantation process.
Two weeks after a positive pregnancy test a trans-vaginal ultrasound scan is performed to assess the pregnancy. At a follow-up ultrasound scan two weeks later the fetus should be visible and heart activity should be present.