Ovarian Induction

In a normal unstimulated menstrual cycle, around 30 primordial follicles will be recruited and stimulated to growth. However, only one of the follicles will become dominant and develop into Graafian follicle. While the dominant follicle develops into Graafian follicle, it will suppress the growth of other follicles and cause them degenerate. Thus, only one egg will become fully mature ( from the Graafian follicle) and ovulate at the mid-cycle.

In a stimulated ovarian-induction cycle, fertility drugs are used to stimulate the ovaries to enhance the growth and maturation of multiple follicles and yield more eggs with better quality. Therefore, several follicles will develop into mature Graafian follicles at the same time and ovulate at the mid-cycle.

There are two types of ovarian induction:

(a) Ovarian Stimulation

This is a simple treatment whereby the ovaries are stimulated with oral drugs (clomiphene citrate) to produce a number of eggs and allow fertilization to occur at timed intercourse. This is the best choice of treatment for those with uncomplicated hormonal disorder and PCOS (polycystic ovarian syndrome).

In this treatment, clomiphene citrate is given daily from Day 3 to Day 7. Follicular tracking by transvaginal scan to monitor the growth of follicles is started on Day 12 every 2 days until follicles are mature. At Metro IVF, mature follicle is defined as follicle that reach the size of 18mm. When follicles mature, the treated couple is advised to have timed intercourse or IUI is perfomed. After two weeks, urine or serum pregnancy test will be carried out to confirm the pregnancy.

 

(b) Controlled Ovarian Hyperstimulation

COH is designed for ovarian stimulation in IVF and ICSI cycles. In COH, GnRH (gonadotropin releasing hormone) agonist or antagonist is used to suppress the LH (lutenizing hormone) levels in the body, as immature elevated LH levels will cause adverse effects on the eggs quality and pregnancy rates. Then, FSH (follicle releasing hormone) is given to stimulate the growth and maturation of multiple follicles. When the eggs reach optimum size of 18mm, ovulation is induced by hCG (human chorionic gonadotropin) injection. hCG is similar with LH. When LH levels exceed a threshold, the eggs will complete their Meiosis I and ovulate. Only fully mature egg with Meiosis I completed can be fertilised by a sperm.

There are three protocols for COH, namely long protocol, short protocol and antagonist protocol. Long protocol applied on younger women and good responders; short protocol applied on older women and bad responders; while antagonist protocol applied on those who have increased risk of developing ovarian hyperstimulation syndrome (OHSS). OHSS is a condition caused by the over-response of ovaries to the stimulation drugs and production of too many mature follicles. The symptoms of OHSS include abdominal pain, diarrhea, nausea and vomiting, abdominal bloating and breathing problems. The complications of OHSS can be severe and should not be taken lightly.

In long protocol, GnRH agonist is started daily in the morning on Day 21 until next menses comes. The dosage of GnRH agonist is reduced on Day 1 and the daily injection is continued until one day before hCG is given. A blood test to measure progesterone level is done on Day 2 and daily night FSH injection is started on Day 3 onwards until the day of hCG. Follicular tracking is performed every two days since Day 7 to monitor the growth of follicles. Another blood test will be done on Day 9 to measure the oestradiol levels. When at least three follicles reach 18 mm, hCG is given to trigger final maturation and ovulation of the eggs. At Metro IVF, the hCG injection is given at 12 midnight and the oocyte pick up will be done in the morning of the day after tomorrow, that is, 34 hours post hCG injection.

In short protocol, hormone assay is done on Day 2 to meansure progesterone levels. On the same day, GnRH agonist is started daily in the morning until one day before hCG is given. Night daily FSH injection is started on Day 3 until the day of hCG given. Follicular tracking is performed every two days since Day 7 to monitor the growth of follicles. Another blood test will be done on Day 9 to measure the oestradiol levels. When at least three follicles reach 18 mm, hCG is given to trigger final maturation and ovulation of the eggs. OPU is then performed 34 hours later.

In antagonist protocol, hormone assay is done on Day 2 to meansure progesterone levels. Daily FSH injection is started on Day 3 until the day of hCG given. Follicular tracking is performed every two days since Day 7 to monitor the growth of follicles. When the leading follicle reach 14mm, GnRH antagonist is started until one day before hCG is given. Another blood test will be done on Day 9 to measure the oestradiol levels. When at least three follicles reach 18 mm, hCG is given to trigger final maturation and ovulation of the eggs. OPU is then performed 34 hours later.