Ovulation Induction

Various ovarian cycle management regimens that have either been used in the past or are still being used. Clomiphene citrate (CC) tablets are administered at a dose of 50-100mg once daily from days 2-6 of the menstrual cycle, i.e. for five days. This regimen may initially lead to the development of some follicles in the ovary but only one usually continues to grow and ovulation of one oocytes usually occurs. The addition of gonadotrophin injections in the latter half of the follicular phase may encourage more of the follicles to continue to develop with the eventual ovulation of more than one oocyte. It is felt that the availability of more than one oocytes for fertilization improves the chance of conception. Some women may not respond to CC or are not suitable candidates for ovulation induction using CC. Such women are administered gonadotrophin injections from Day 2 of the menstrual cycle or on the second day of a withdrawal bleed following pre-treatment with progesterone preparations or combined oral contraceptive tablets. The dose of gonadotrophin injection is usually 75-150 IU administered daily or every other day. The last regimen involves the use of GnRHa, to prevent a premature surge of luteinizing hormone (LH) secretion by the pituitary gland.

Types Ovulation Induction

  • Natural ovarian cycle
  • CC
  • CC + Gonadotrophins
  • Gonadotrophins
  • GnRHa + Gonadotrophins

Ultrasound scanning provides the most practical method for monitoring follicular development during IUI treatment. The follicle becomes visible using transvaginal ultrasound scanning by the time its diameter is between 2 and 3 mm. Its growth is usually linear and the diameter increases by 2-3 mm per day. Ovulation occurs when the follicular diameter reaches 18-24mm. Ultrasound scanning will also demonstrate progressive thickening of the endometrial layer, which ideally should be more than 9mm thick. Monitoring ovarian response to stimulation by serial oestradiol assays is not very useful during IUI treatment as the ultrasound provides adequate evidence of follicular growth.

An injection of 10000 IU of HCG is administered once the diameter of the leading follicle reaches 18mm or more.