The IVF-ET steps

In vitroLatin for "in glass" for example in a test tube, as opposed to processes taking place inside the body. fertilizationFusion of an egg and a spermatozoon, fertilization occurs naturally in the fallopian tubes. and embryoTerm designating the early stages of development from conception to the eighth week of pregnancy. From the first cell division on, the two-cell stage, one uses the term embryo. transfer (IVF-ET) is a technique which consists in emptying each ovarian follicleFluid-filled sac in the ovary containing and nourishing the egg during its maturation. During ovulation, the follicle bursts and releases the egg. obtained through hormonal stimulationOvarian stimulation. Medical treatment designed to stimulate the ovaries, the follicular growth and development. This treatment usually allows several oocytes to become mature. by puncturing it with a medical hollow needle (oocyteA female reproductive cell. At birth, the ovaries contain 1 to 2 million oocytes. At puberty, there are no more than 400'000 to 500'000 left. Only 400 to 500 will reach maturity and ovulation at a rate of  one per month until menopause. All the others will finally degenerate at various stages of development. pick-up), isolating cumulus-oocyteA female reproductive cell. At birth, the ovaries contain 1 to 2 million oocytes. At puberty, there are no more than 400'000 to 500'000 left. Only 400 to 500 will reach maturity and ovulation at a rate of  one per month until menopause. All the others will finally degenerate at various stages of development. complexes and putting them in the presence of the partner's spermEjaculated spermatozoa and secretions during the male orgasm.. After an incubation of 16-20 h, zygotes (impregnated ova) are identified. Of these, 1-3 zygotes are cultured prior to the transfer of fresh embryos (ET), while the remaining are immediately cryopreserved for later use. According to the Swiss law (LPMAThe Swiss Law on Medically Assisted Procreation (2001).), supernumerary zygotes have to be frozen before the first cellular division and can be thawed in groups of 1 to 2, exceptionally 3, in subsequent cycles.

Originally developed to treat tubal infertilityInfertility due to the obstruction or dysfunction of the fallopian tubes. (tubal occlusion), IVF-ET indications have progressively been extended (endometriosisGynecological problem where one finds some tissue of the endometrium (uterine lining) outside  the uterus either on the fallopian tubes, ovaries or in the abdominal cavity. Endometriosis can be the cause of painful periods and is also a factor infertility., unspecified male infertilityDifficulty for a man or a woman to procreate as a result of a functional disorder or an organic lesion of the reproductive system, generally acknowledged after one year of regular, unprotected sexual relations. ...). It is now often associated with the ICSIFrom English "Intra-Cytoplasmic Sperm Injection." Assisted fertilization by microscope, where a single sperm is injected directly into the oocyte. ICSI is indicated in cases of male fertility problems, so if there are only very few normal sperm in the sperm or the fertilization capacity of sperm is extremely small. technique (see under "fertilizationFusion of an egg and a spermatozoon, fertilization occurs naturally in the fallopian tubes." in left column) or microsurgical collection of spermEjaculated spermatozoa and secretions during the male orgasm. from the epididymis (MESAFrom English "Microsurgical epididymal sperm aspiration." Microsurgical aspiration of sperm directly into the epididymis (a long tubular and tortuous structure in which spermatozoa are getting mature and are stored). Sperm retrieved are used for fertilization by intracytoplasmic injection (ICSI).) or testis (TESE"Testicular sperm extraction". Microsurgical technique to extract sperm directly from a testicular biopsy. The sperm obtained from testicular tissue are used for fertilization by intracytoplasmic sperm injection (ICSI). TESE is applied in cases where the epididymis does not store sperm, or is absent (see also ICSI and MESA).).

Indications: tubal infertilityInfertility due to the obstruction or dysfunction of the fallopian tubes., subfertilityReduced fertility. of male origin, unexplained subfertilityReduced fertility..

An IVF cycle is divided into several steps according to the diagram below:

1. Ovarian stimulationMedical treatment designed to stimulate the ovaries, the follicular growth and development. This treatment usually allows several oocytes to become mature.
2. Collection of oocytes
3. FertilizationFusion of an egg and a spermatozoon, fertilization occurs naturally in the fallopian tubes.
4. Identification of zygotes
5. Cultivation and freezing of zygotes
6. EmbryoTerm designating the early stages of development from conception to the eighth week of pregnancy. From the first cell division on, the two-cell stage, one uses the term embryo. transfer

Main steps of an IVF cycle