San Diego's Premier Fertility Center: Reproductive Sciences Center & Genetics Institute

Infertility Related Terms

ART - See Assisted Reproductive Technologies

Assisted Egg Activation - A procedure in which eggs that have been injected with a sperm (that is, they have already undergone ICSI) are treated with a chemical agent that induces egg activation and triggers the fertilization process. This procedure is used in situations in which fertilization is absent or very poor even using ICSI. This an ongoing area of research at Reproductive Sciences Center.

Assisted Hatching - A micromanipulation technique in which the shell around the egg (the zona pellucida) is opened or thinned to facilitate the embryo hatching process and subsequent implantation. Details on assisted hatching.

Assisted Reproductive Technologies - All treatments or procedures that include the handling of human oocytes or embryos for the pupose of generating a pregnancy. That is, all procedures that begin with the removal of oocytes from the ovary. This would include in vitro fertilization (IVF), gamete intrafallopian transfer (GIFT), frozen embryo transfer (FET) and related procedures.

Blastocyst - The stage at which an embryo acquires the ability to implant in the wall of the uterus. Embryos usually reach this stage 5-6 days after egg retrieval (ovulation). More on blastocyst transfer.

Blastocyst Freezing - The freezing of an embryo at the blastocyst stage. Details on blastocyst freezing.

Cytoplasmic Transfer - Cytoplasmic transfer involves the injection of a small amount of cytoplasm (the viscous semifluid inside an egg) taken from a donor egg directly into a patient's eggs. It is performed on the eggs of women who have previously failed an IVF cycle due to poor quality embryos and is intended to improve the quality of her embryos in a subsequent cycle. Details about cytoplasmic transfer.

Day of Transfer - The day on which embryos are transferred. The day of egg retrieval is designated "Day 0," with most transfers occurring on Day 2,3 or 5 (blastocyst transfer). Details about the day of transfer.

Egg (Oocyte) Cryopreservation - The process of freezing, storaging and thawing eggs before fertilizing them. It is a consideration for women who are at risk for losing their childbearing potential (e.g., from radiation of chemotherapy for cancer) and for women who wish to delay childbearing until an age at which fertility rates are significantly reduced (age 35 or over).

Egg Retrieval - See Oocyte Retrieval.

Embryo Cryopreservation (Freezing) - Embryo cryopreservation (the process of freezing, storage and thawing embryos) can enhance pregnancy rates by allowing excess embryos not replaced in a fresh embryo transfer to be stored for future use. Embryo freezing may also be performed when a fresh embryo transfer is not performed for any of the following reasons: (1) Risk of ovarian hyperstimulation syndrome (OHSS), (2) Poor quality endometrium (a thin uterine lining), (3) Intermenstrual bleeding, (4) Planned "banking" cycle in which the patient elects to store all embryos, (5) Extremely difficult embryo transfer. Embryos are placed into straws or vials containing anti-freeze or cryoprotectant solutions. These are transferred to a programmable biological freezer which is used to achieve a controlled slow rate of cooling. During cooling, cells dehydrate and as the temperature is reduced, more ice forms and water is removed gradually from the cells. Slow cooling is continued to ~ -35° C at which point embryos are rapidly cooled by plunging into liquid nitrogen (-196° C). Embryos are kept in storage tanks of liquid nitrogen until thawing is performed.

Embryo Culture - The culture of fertilized eggs in the laboratory to allow them to develop into early cleavage stage embryos and progress thorough to the pre-implantation blastocyst stage. Details on embryo culture.

Embryo Donation - Couples who have excess frozen embryos can elect to donate them for other couples attempting to become pregnant. Details on embryo donation.

Embryo Grading and Selection for Transfer - Assigning a letter grade (some centers use a numerical system) to each embryo in order to identify the best quality embryos, which are then selected for embryo transfer or cryopreservation. (details)

Embryo Transfer (Intrauterine) - Placement of embryos into a woman's uterus through the cervix in an IVF/ICSI cycle or frozen embryo transfer procedure. Embryos are loaded into a narrow plastic tube (catheter) which is placed carefully into the uterine cavity, and the embryos are then gently expelled through the end of the tubing.

Fertilization Check - A laboratory procedure performed on the day after egg retrieval to determine which eggs have fertilized normally and thus can potentially be used for embryo culture and transfer. Details on fertilization check.

Gamete Intrafallopian Transfer (GIFT) - An ART procedure in which eggs are removed from a woman's ovaries, combined with washed sperm, and then both eggs and sperm are placed into the woman's fallopian tube(s) through a small incision in her abdomen. The procedure is performed by laparoscopy. Details on GIFT.

hCG (human chorionic gonadotropin) - A protein hormone made by the placenta that is detectable in a pregnant woman's blood (and urine) soon after implantation. The measurement of one part of this hormone, beta-hCG, is the basis for commercially available tests for pregnancy.

Intracytoplasmic Sperm Injection (ICSI) - ICSI is a procedure in which a single sperm is injected directly into an egg. This technique is used to overcome severe male infertility. Details about ICSI.

In Vitro Fertilization (IVF) - An ART procedure that involves removing eggs from the ovaries, fertilizing them in a laboratory by the addition or injection of washed sperm, culturing the fertilized eggs and transferring the resulting embryos into the woman's uterus through the cervix. Details about IVF.

LH (Leutinizing Hormone) - A protein hormone produced by the pituitary gland that triggers ovulation and supports the production of estrogen and progesterone after ovulation in the second half of the menstrual cycle. Because large amounts of LH are released prior to ovulation, it can be detected in urine and used to predict ovulation. Detection of LH in urine is the basis of commercially available ovulation predictor kits. Because LH is metabolized too rapidly to be effective when administered by injection, a similar but more potent hormone, human chorionic gonadotropin (hCG), is used by fertility specialists to induce ovulation.

Oocyte (Egg) Retrieval - A procedure to collect eggs (oocytes) from the ovarian follicles using an ultrasound-guided transvaginal (through the top of the vagina) needle aspiration technique. Egg recovery is performed 34 to 36 hours after the administration of hCG, which is given to induce ovulation. The egg retrieval is performed in the procedure room adjacent to the IVF laboratory by your physician. An embryologist examines the follicular fluid and follicular flushing solutions aspirated from each follicle to locate and identify oocytes. Eggs are collected into culture media, washed and transferred to the IVF laboratory where they are evaluated for viability and maturity.

Preimplantation Genetic Diagnosis (PGD) - The genetic testing of an embryo prior to embryo transfer. One or two cells are removed from an embryo after 3 days of culture in a procedure called embryo biopsy and tested either for a specific genetic disorder (e.g., cystic fibrosis) or for an abnormal number of chromosomes (e.g., trisomy 21 - Down's syndrome). PGD is also performed for gender selection. Details about PGD.

Timed Intercourse - Timing intercourse to immediately precede the release of the egg from the ovary (ovulation). If ovulation is spontaneous, timing is usually done using urine ovulation predictor (LH) kits, sometimes in conjunction with blood tests and ultrasound. A fertility specialist may also induce ovulation by administering an injection of an LH-like substance, Human Chorionic Gonadotropin (hCG).

Tubal Embryo Transfer (TET) - The transfer of embryos to the fallopian tubes for the purpose of achieving a pregnancy. Embryos may be transferred at the fertilized oocyte (zygote) stage in a ZIFT (zygote intrafallopian transfer) procedure, or 24 hours later at the 2- to 6-cell stage in a TET procedure. Details about TET.

ZIFT- See Tubal Embryo Transfer