In vitro fertilisation

In vitro fertilisation (IVF) is a technique in which egg cells are fertilized outside the woman's body. IVF is a major treatment in infertility where other methods of achieving conception have failed.

Method

Ovarian stimulation

Treatment cycles are typically started on the third day of menstruation and 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. Endogenous ovulation is blocked by the use of GnRH agonists or GnRH antagonists.

Related Topics:
Menstruation - Follicles - Gonadotropin - FSH - Estradiol - Gynecologic ultrasonography - GnRH

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Oocyte retrieval

When follicular maturation is judged to be adequate, human chorionic gonadotropin (β-hCG) is given. This agent, which acts as an analogue of luteinizing hormone, would cause ovulation about 42 hours after injection, but a retrieval procedure takes place just prior to that, in order to recover the egg cells from the ovary. The eggs are retrieved from the patient using a transvaginal technique involving an ultrasound-guided needle piercing the vaginal wall to reach the ovaries. Through this needle follicles can be aspirated, and the follicular fluid is handed to the IVF laboratory to identify ova. The retrieval procedure takes about 20 minutes and is usually done under conscious sedation or general anesthesia.

Related Topics:
Human chorionic gonadotropin - Luteinizing hormone - Conscious sedation - General anesthesia

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IVF laboratory

In the laboratory, the identified eggs are stripped of surrounding cells and prepared for fertilization. In the meantime, semen provided by the male partner is prepared for fertilization by removing inactive cells and seminal fluid. The sperm and the egg are incubated together (at a ratio of about 75,000:1) in the culture media for about 18 hours. By that time fertilization should have taken place and the fertilized egg would show two pronuclei. In situations where the sperm count is low a single sperm is injected directly into the egg using intracytoplasmic sperm injection (ICSI). The fertilized egg is passed to a special growth medium and left for about 48 hours until the egg has reached the 6-8 cell stage.

Related Topics:
Semen - Culture - Fertilization - Pronuclei - Intracytoplasmic sperm injection

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Laboratories have developed grading methods to judge oocyte and embryo quality. Typically, embryos at the 6-8 cells stage are transferred three days after retrieval. In many programs, however, embryos are placed into an extended culture system with a transfer done at the blastocyst stage, especially if many day-3 embryos are available. Blastocysts tend to give higher pregnancy rates.

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Embryo transfer

The embryos judged to be the "best" are transferred to the patient's uterus through a thin, plastic catheter, which passes through her vagina and cervix. Often, several embryos are passed into the uterus to improve chances of implantation and pregnancy.

Related Topics:
Catheter - Vagina - Embryo - Implantation - Pregnancy

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Post-transfer

The patient has to wait two weeks before she returns to the clinic for the pregnancy test. During this time she may receive progesterone - a hormone that keeps the uterus lining thickened and suitable for implantation. Many IVF programs provide additional medications as part of their protocol.

Related Topics:
Pregnancy - Progesterone

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