Theoretically, in vitro fertilization could be performed by aspirating contents from a woman's fallopian tubes or uterus with a plastic catheter after natural ovulation, mix it with semen from a man and reinsert into the uterus. However, without additional techniques, the chances of pregnancy would be extremely small. Such additional techniques that are routinely used in IVF include ovarian hyperstimulation to retrieve multiple eggs, ultrasound-guided transvaginal oocyte retrieval directly from the ovaries, egg and sperm preparation, as well as culture and selection of resultant embryos.
Ovarian hyperstimulation
There are two main protocols for stimulating the ovaries for IVF treatment. The long protocol involves downregulation (suppression or exhaustion) of the pituitary ovarian axis by the prolonged use of a GnRH agonist. Stimulation of the ovaries using a gonadotrophin starts once the process of downregualtion is complete generally after 10 to 14 days.
The short protocol consist of a regimen of fertility medications to stimulate the development of multiple follicles of the ovaries. In most patients, injectable gonadotropins (usually FSH analogues) are used under close monitoring. Such monitoring frequently checks the estradiol level and, by means of gynecologic ultrasonography, follicular growth. Typically approximately 10 days of injections will be necessary. Spontaneous ovulation during the cycle is typically prevented by the use of GnRH agonists that are started prior or at the time of stimulation or GnRH antagonists that are used just during the last days of stimulation; both agents block the natural surge of luteinising hormone (LH) and allow the physician to start the ovulation process by using medication, usually injectable human chorionic gonadotropins. Ovarian stimulation carries the risk of excessive or hyperstimulation. This complication is life-threatening and ovarian stimulation using gonadotrophins must only be carried out under strict medical supervision
Ovarian hyperstimulation
There are two main protocols for stimulating the ovaries for IVF treatment. The long protocol involves downregulation (suppression or exhaustion) of the pituitary ovarian axis by the prolonged use of a GnRH agonist. Stimulation of the ovaries using a gonadotrophin starts once the process of downregualtion is complete generally after 10 to 14 days.
The short protocol consist of a regimen of fertility medications to stimulate the development of multiple follicles of the ovaries. In most patients, injectable gonadotropins (usually FSH analogues) are used under close monitoring. Such monitoring frequently checks the estradiol level and, by means of gynecologic ultrasonography, follicular growth. Typically approximately 10 days of injections will be necessary. Spontaneous ovulation during the cycle is typically prevented by the use of GnRH agonists that are started prior or at the time of stimulation or GnRH antagonists that are used just during the last days of stimulation; both agents block the natural surge of luteinising hormone (LH) and allow the physician to start the ovulation process by using medication, usually injectable human chorionic gonadotropins. Ovarian stimulation carries the risk of excessive or hyperstimulation. This complication is life-threatening and ovarian stimulation using gonadotrophins must only be carried out under strict medical supervision
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