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FSH
FSH is the hormone which travels from the pituitary gland to the ovary, telling the ovary to grow and mature eggs each month. FSH is available in ampoules. Each ampoule has a dose of 75 or 150 units.
Treatment with FSH is the most powerful and reliable treatment for patients with ovulation disorders. Pregnancy rates of up to 15% per treatment cycle can be expected. The overall pregnancy rate for patients who need and use this treatment is in the order of 60% per patient. Unlike Clomid, the more serious the ovulation disturbance, the more likely FSH is to work.
The aim of giving FSH treatment is to mimic the normal egg development during the menstrual cycle. FSH injections are therefore given each morning as an intramuscular injection. It is best to start with the lowest dose of FSH per day (using 75 units per day). These doses are used for 4 to 6 days at a time. The ovarian response is determined by measuring oestrogen levels in the blood.
When the oestrogen begins to rise, the FSH is successfully growing an egg or eggs. If there is no response to a dose of FSH in 5-6 days of injections the dose will be increased. The normal dose increments are 75 units, 112 units, 150 units and 225 units per day. Most patients respond with 75 to 150 units per day. However it is very important that increments are only made cautiously. The ovary is very sensitive to FSH dosage and too much FSH rapidly grows multiple eggs. It is important that patients receiving FSH therapy start with the lowest possible dose and the increments in the dose are only made gradually after a trial of a particular dose for at least five to seven days.
When the blood levels of oestrogen rise to a point consistent with the mature egg an ultrasound scan will be done. The size and number of follicles (egg containing cysts) growing on the ovary can be measured. Follicle sizes of 14 to 20 mm usually indicate a mature egg. It is important to know the number of follicles present to minimise the risk of a multiple pregnancy.
If conditions are favourable, release of the egg is then initiated. The egg is released by giving an injection of hormone called Human Chorionic Gonadotrophin (HCG). HCG is a natural pregnancy hormone. It has a structure almost identical to LH and can therefore be used to trigger egg maturation and release. A dose of 2,000-5,000 units of HCG is given as an intramuscular injection. Egg release will occur 36 to 44 hours later. The HCG injection is therefore given 1½ to 2 days prior to intercourse or insemination.
HCG is also used to provide support to the ovary in the second half of the cycle after ovulation has occurred. As the first half of the cycle has been artificially created with FSH injections it is important to support the second half of the cycle. If this is not done there will be insufficient progesterone production and the pregnancy will find it very hard to implant as the corpus luteum undergoes premature degeneration. HCG injections 3 days and 7 days after ovulation will prevent this and provide appropriate early pregnancy support.
Side effects of FSH treatment are few. FSH is a natural hormone and apart from the inconvenience of a daily injection has little side effects. The major risks of FSH therapy are those of multiple pregnancy and overstimulation. Multiple pregnancy rates are up to 20% of all pregnancies produced by this treatment. If FSH treatment is not strictly controlled it is treatment with this ovulation drug which causes high order multiple pregnancies such as quins and sextuplets. The combination of oestrogen levels and ultrasound scan should be used to assess the likely number of eggs being released by the HCG injection. If more than two or three eggs are likely to be released, cancellation should be discussed with the patient.
It is very difficult in some patients, especially those with PCOS to choose the correct dose of FSH. If too little FSH dosage is used then no eggs grow. If the dose is increased only a very small amount sometimes many eggs grow on the ovary, often as many as 15 or 20. In some patients with PCOS there is no correct dose. Some patients with PCOS therefore have a very high risk of multiple pregnancy when FSH is used. Conversion to an IVF cycle is often used to control multiple pregnancy risk by only replacing one or two embryos. IVF pregnancy rates can be up to 40-50% per cycle depending on age.
If too much FSH is given the patient may develop over-stimulation syndrome. This is characterised by sore ovaries and a very swollen abdomen. It occurs about 7 to 10 days after ovulation and mostly in patients who are pregnant. It is actually very rare in patients who are having ovulation induction with FSH and then intercourse. Usually these patients do not have enough eggs growing to make overstimulation syndrome common. It is however much more common in patients who grow large numbers of eggs with FSH, usually on the IVF program.
The advantages of FSH treatment therefore include:
- High pregnancy rates
- Powerful management of serious ovulation disorders
- Conversion to versions of the IVF program can occur with high pregnancy rates.
The disadvantages of FSH treatment are:
New forms of FSH have the advantage of being able to be given by a smaller less painful subcutaneous injection. This is a small injection using a fine needle, which just goes under the surface of the skin into the fat rather than the deeper bigger injection into the muscle.
