Assisted Reproductive Technology (ART) – Glossary

Assisted Reproduction Technology (ART): In vitro handling of eggs or sperm and embryos to establish a pregnancy.

Aneuploidy: The loss or gain of one or more chromosomes

Anovulation: Suspension or cessation of ovulation.

Artificial insemination: Introducing sperm into the female reproductive tract not through sexual intercourse.

Assisted Hatching: An in vitro procedure in which the zona pellucida of an embryo (usually at 8-cell stage or a blastocyst) is perforated by chemical, mechanical or laser-assisted methods to assist separation of the blastocyst from the zona pellucida.

Blastocyst: 5-6 days old embryo ‘after fertilisation’.

Biochemical pregnancy ‘Pre-clinical pregnancy’: Proof of conception based only on biochemical test of the serum or urine but no clinical pregnancy results.

Clinical pregnancy: A pregnancy that fulfils one of the following criteria:

Ø     Pregnancy ongoing at 20 weeks

Ø     Ultrasound evidence of an intrauterine sac (with or without a fetal heart)

Ø     Products of conception showing chorionic villi

Ø     A definite ectopic pregnancy diagnosed by laparoscope or by ultrasound.

Clinical pregnancy rate: number of clinical pregnancies expressed per 100 treatment events. When clinical pregnancy rates are described, the precise treatment event that is being used as a denominator must be specified.

Clone: A copy of a DNA molecule, a stem cell or an individual. Cloning of an individual is done by replacing the nucleus of an egg cell with the genetic material from a somatic ‘non-germ’ cell. Cloning can also be done to produce stem cells, the undifferentiated early cells from which all types of cells develop. This technique may in future enable people to access life-saving treatments tailored-made from their own DNA.

Cryopreservation: Freezing and storage of sperm, eggs, embryos or ovarian and testicular tissues.

ART cycle: A period of up to 30 days during which either controlled ovarian hyperstimulation has been performed with the intention of applying assisted reproductive technology, or assisted reproductive technology has been applied to patient care.

Cancelled cycle: an ART cycle in which controlled ovarian hyperstimulation has been performed with the intention of applying assisted reproductive technology but assisted reproductive technology has not been used.

Controlled Ovarian Hyperstimulation (COH): Medical treatment to induce the development of multiple ovarian follicles.

Congenital abnormality: Abnormality existing at birth, regardless of cause.

Delivery rate: Number of deliveries per 100 initiated cycles, aspiration cycles or embryo transfer cycles; the denominator (initiated, aspirated or embryo transfer cycles) must be specified. It includes deliveries that resulted in a live birth and/or stillbirth. The delivery of a singleton, twin or other multiple pregnancy is registered as one delivery.

Ectopic pregnancy: The embryo implant outside the uterine cavity.

Embryo: Product of conception up to eight weeks after fertilisation, later it is called a foetus. 

Embryo Donation: Transfer of an embryo that did not originate from the recipient and her partner.

Embryo Transfer (ET): One or more embryos are placed in the uterus or fallopian tube.

Embryo Transfer Cycle: ART cycle in which one or more embryos are transferred into the uterus or fallopian tube.

Endometriosis: Condition where endometrial tissue grows in areas other than the uterine cavity.

FER: frozen embryo replacement.

Early Neonatal Neath: Death occurring within the first seven days after delivery.

Fertilisation: A sperm penetrates the egg with fusion of genetic material resulting in a fertilised egg and development of a zygote.

Follicle: A fluid filled sac that contains an immature egg. Located in the ovaries, follicles develop each cycle, one ovulates into an egg.

Fetus: The product of conception starting from completion of embryonic development (at eight completed weeks after fertilisation) until birth or miscarriage.

Full-Term Birth: A birth that takes place at 37 or more completed weeks of gestational age. This includes both live births and stillbirths.

Gamete: A reproductive cell, egg in females and sperm in males

Gamete intra-fallopian transfer (GIFT): Process by which eggs and sperm are transferred to the Fallopian tube.

Gestational age: Age of an embryo or fetus calculated by adding two weeks to the number of completed weeks since fertilisation.

Gestational sac: A fluid-filled structure arising from trophoblastic tissue that develops early in pregnancy usually within the uterus.

Hatching: The process that precedes implantation by which an embryo at the blastocyst stage separates from the zona pellucida.

Implantation: The attachment and subsequent penetration by the zona-free blastocyst (usually in the endometrium) that starts five to seven days following fertilisation.

Infertility: Failure to conceive after 12 months of regular unprotected sexual intercourse.

Intracytoplasmic sperm injection (ICSI): An IVF procedure in which a single spermatozoon is injected through the zona pellucida into the oocyte.  The process increases the likelihood of fertilisation when there are abnormalities in the number, quality or function of the sperm.

Intrauterine Insemination (IUI): Artificial insemination of semen washed or un-washed directly into the uterus.

In vitro fertilisation (IVF): Fertilisation of an egg by sperm outside the body in a laboratory dish.

Karyotype: The chromosome set.

Live Birth: the birth of a live fetus after 20 weeks gestation.

Live Birth Rate: Number of live births expressed per 100 treatment events. When calculating a live birth rate, more than one live birth occurring at a single delivery (i.e. from a twin or triplet pregnancy) should be counted as a single event. When live birth rates are described, the precise treatment event that is being used as a denominator must be specified.

Malformation rate: Includes all structural, functional, genetic and chromosomal abnormalities identified in aborted tissue, or diagnosed before or after birth.

Microsurgical Epididymal Sperm Aspiration (MESA): Microsurgical collection of sperm direct from the epididymis (tube that carries sperm out of the testis). Used when a blockage in the epididymis leads to absence of sperm in the semen.

Micromanipulation (assisted fertilisation): Use of special micromanipulative technology that allows operative procedures to be performed on the oocyte, sperm or embryo.

Miscarriage: Spontaneous loss of a clinical pregnancy before 20 completed weeks of gestation.

Neonatal Death: Death within 28 days of birth.

Oocyte Donation: A woman donating her oocytes (eggs) to enable a recipient to have a child. The recipient will be the Social Mother and the donor is th Genetic Mother.

Oocyte Pick-Up (OPU): Initiated ART cycle in which one or more oocytes are retrieved by aspiration.

Ovarian HyperStimulation Syndrome (OHSS): Ovarian hyperstimulation syndrome (OHSS) is a rare, medical complication for ovarian stimulation by assisted reproduction technology and other infertility treatments. Following gonadotropin therapy, OHSS usually develops several days after oocyte retrieval or assisted ovulation. This syndrome is characterized by ovarian enlargement due to multiple ovarian cysts and fluid shift into the extra-vascular space (abdomen). Complications of OHSS include ascites, hemoconcentration, hypovolemia, and electrolyte imbalances.

Percutaneous Epididymal Sperm Aspiration (PESA): Collection of sperm under local anaesthesia by needle aspiration of the epididymis.

Polycystic Ovarian Syndrome (PCOS): a condition characterised by irregular or absent menstruation, acne, obesity and excess hair growth.

Pre-implantation genetic diagnosis (PGD): Genetic tests on a 3 day / 6-8 cell stage embryo. One cell is removed for analysis of its DNA or chromosomes to detect genetic and/or chromosomal disorders before embryo transfer.

Pre-implantation genetic screening (PGS): Technique to check if an embryo has the correct number of chromosomes; used for older women ‘at increased risk of chromosomal abnormalities’, women who have had recurrent miscarriages ‘often due to chromosomal abnormalities’ or women who had a baby with chromosomal abnormality.

Preterm Birth: a birth which takes place after at least 20, but less than 37, completed weeks of gestation.

Single Embryo Transfer: Selecting one embryo for transfer to lower the risk of multiple pregnancies.

Spontaneous Miscarriage: spontaneous loss of a clinical pregnancy before 20 completed weeks of gestation or, if gestational age is unknown, a weight of 500g or less.

Stillbirth / Fetal Death: death of a fetus before it is born at or after 20 weeks of pregnancy.

Subfertility: The chance of becoming pregnant (fecundability or monthly fertility) is reduced.

Testicular sperm aspiration (TESA): Needle aspiration of the testis to collect sperm, usually carried out in cases where PESA has been unsuccessful.

Testicular sperm extraction (TESE): done when other extraction methods were unsuccessful 

Vitrification: an ultra-rapid freezing method for eggs and embryos. It avoids the damage usually caused in freezing from ice crystals.

Zygote Intrafallopian Transfer (ZIFT): The zygote is transferred into the fallopian tube.

Zygote: A diploid cell, results from the complete fertilisation of an egg by a sperm.

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