Fertilityone2one UK



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Abandoned Cycle: When an IVF treatment cycle is cancelled after commencing administration of drugs, but before egg collection.

AID: Artificial insemination (of a woman) using donated gametes. Now more commonly referred to as donor insemination (DI) to avoid confusion with AIDS.

AIH: Artificial insemination (of a woman) using husband's sperm.

AIP: Artificial insemination (of a woman) using her partner's sperm.

Amniocentesis: A procedure usually carried out between 14 and 18 weeks of pregnancy, in which amniotic fluid is withdrawn from the amniotic sac in which
the foetus is developing. The fluid and the foetal cells it contains may be tested for genetic disease in the foetus.

Amnion: The inner membrane forming the sac in which the embryo develops.

Amniotic fluid: The fluid filling the cavity between the embryo and the amnion.

Ampoules: The small glass vials in which many fertility drugs are provided.

Assisted Hatching: The mechanical, laser or chemical breaching of the zona pellucida (outer layer) of the egg.

Assisted Reproductive Technologies (ARTs): The collective name for all techniques used artificially to assist women to carry children, including IVF and ICSI.

Asthenozoospermia: A lower than normal number of sperm in the ejaculate of a man.


Blastocyst: An embryo that has developed for five to six days after fertilisation.

Blastocyst transfer: Transfer of an embryo that has developed for five to six days after fertilisation.

Blastomere: A cell taken (by biopsy) from a blastocyst.


Cell: The basic unit of all living organisms. Complex organisms such as humans are composed of somatic (body) cells and germ line (reproductive) cells.

Cervical mucus: The secretions surrounding the cervical canal. The amount and texture changes during ovulation to allow sperm penetration.

Cervix: The narrow passage at the lower end of the uterus (womb), which connects to the vagina.

Chlamydia: A sexually transmitted disease which can cause damage to the female and male reproductive systems resulting in infertility. Chlamydia may remain undetected for long periods of time.

Chorion: The outer membrane tissue of the primitive placenta.

Chorion villus sampling (CVS): A procedure, usually between 8 and 12 weeks of pregnancy, by which a small amount of the chorionic villi from the placenta is biopsied for genetic analysis.

Chromosome: A threadlike structure of DNA and associated proteins which is found in the nucleus of a cell. Chromosomes carry genetic information in the
form of genes.

Cleavage: The process which occurs to the zygote (cell formed by fertilisation) to result in a blastocyst.

Clomid: A drug used in stimulated DI and IUI cycles.

Clomiphene: A fertility drug which stimulates the production of one or more follicles and therefore increases the chances of pregnancy.

Cloning: The production of two or more genetically identical individuals by nucleus substitution or by mechanical division of a cleaving zygote to yield identical cells each of which can form a new individual. Also known as Cell
Nuclear Replacement (CNR).

Congenital malformations: Any malformation which is noticed at birth, whether the result of a genetic (inherited) or environmental cause.

Counselling: Aims to enable patients to understand the implications of infertility treatment, to give emotional support and to help the patient cope with the consequences of treatment.

Cryopreservation: The storage of gametes or embryos by freezing at low temperatures.

Cyclogest: A drug which can be taken rectally or vaginally and supports the hormone levels of patients undergoing fertility treatment following insemination.

Cytomegalovirus (CMV): A member of the herpes groups of viruses. Most
adults and children who catch CMV have no symptoms, although some people may get a fever, sore throat, fatigue and swollen glands. CMV is of most risk to unborn children of women who get CMV for the first time during pregnancy.
About 7 to 10% of these babies will have symptoms at birth or will develop disabilities including mental retardation, small head size, hearing loss, and
delays in development.


DeoxyriboNucleicAcid (DNA): The major constituent of chromosomes, and
the hereditary material of all living organisms.

Dizygotic: Derived from two (di) eggs (zygote). Dizygotic twins form when two separate eggs are fertilised by separate sperm.

Donor: Person who consents to allow their gametes or embryos to be used in the treatment of others or for research purposes. Although donors are the genetic parents of children created using their gametes, if the treatment is provided in a licensed centre in the UK they are not the legal parents of these children.

Donor Insemination (DI): The introduction of donor sperm into the vagina, the cervix or womb itself.


Egg: The gamete produced by females during their monthly cycle. The egg is also known as an oocyte.

Egg collection: Procedure by which eggs are collected from the woman's ovaries by using an ultrasound guided needle, or by using a laparoscope (an instrument used for looking into the abdomen) and a needle. Also known as egg retrieval.

Egg donation: The process by which a fertile woman donates her eggs to be used in the treatment of others or for research.

Egg sharing: An arrangement where a woman seeking IVF treatment undergoes one cycle of treatment in which her eggs are recovered. She then uses a proportion of these eggs in her own treatment and donates the remaining eggs to another woman. The woman donating her eggs receives a reduction in the cost of her treatment.

Embryo: A fertilised egg that has the potential to develop into a foetus.

Embryo biopsy: The removal and culture of one or two cells from an embryo in vitro prior to genetic screening.

Embryo division: The splitting of an in vitro embryo at an early stage when each section may continue development. This may produce multiple copies of the single original embryo, and may be considered a form of cloning ? fission cloning.

Embryo freezing: Embryos not required for treatment in a cycle can be frozen and stored for future use. Freezing is also known as cryopreservation.

Embryo storage: The storage of one or more embryos for future use by freezing (cryopreservation).

Embryo transfer: The replacement of embryos back into the female patient.

Endometriosis: A female condition in which endometrial cells which normally line the uterus, implant around the outside of the uterus and/or ovaries, causing internal bleeding, pain and reduced fertility.

Endometrium: The lining of the womb which grows and sheds during a normal menstrual cycle and which supports a foetus if a pregnancy occurs

Epididymis: A highly convoluted tube about seven metres long that connects the testes to the vas deferens. The sperm are moved along the tube and are stored in the lower part until ejaculation.


Fallopian tube(s): The pair of tubes which lead from the ovaries to the uterus (womb). After release of the egg from one of the ovaries, the tube transports the egg to the uterus. The tubes are the site of fertilisation in natural conception.

Fertilisation: The penetration of an egg by a sperm and the formation of an embryo from this. Naturally fertilisation occurs in the woman's body (in vivo) but it can also occur in the laboratory (in vitro).

Fibroid: A ball of fibrous muscular tissue which may grow in the muscular wall of the uterus. This can cause pain and excessive menstrual bleeding and result in impaired fertility.

Flow cytometry (sperm sorting): A method of sperm sorting that involves staining the X and Y chromosome-bearing sperm with different fluorescent dyes, and then sorting them according to the colour. Used for sex selection.

Fetus: The term used for an embryo after the eighth week of development until birth.

Follicle(s): A small sac in the ovary in which the egg develops.

Follicle Stimulating Hormone (FSH): Hormone produced by the pituitary gland which stimulates the production of follicles by the ovary. Used in assisted conception to stimulate the production of more than one follicle (ovulation induction).


Gamete: The male sperm or female egg which fuse together to form a zygote.

Gamete Intra Fallopian Transfer (GIFT): A procedure in which eggs are retrieved from a woman, mixed with sperm and immediately replaced in one or other of the woman's fallopian tubes so that they fertilise inside the body (in vivo).

Gene. A dominantly inherited genetic disease occurs when only one copy of the gene is sufficient to produce the disease e.g. Huntington's chorea. A recessively inherited disease only occurs if both copies of the defective gene are present e.g. Tay-Sachs' disease, Sickle cell disease.

Genome: The basic set of genes in the chromosomes in any cell, organism or species.

Gestone: A drug taken by injection following fertility treatment to support hormone levels.

Gonadotrophin Releasing Hormone (GnRH): Hormone released by the hypothalamus which stimulates the pituitary to produce Luteinising Hormone (LH) and Follicle Stimulating Hormone (FSH).

Gonadotrophins: Drugs used to stimulate the ovaries similar in composition.

Gradient methods (sperm sorting): A method of sorting sperm based on the different constitution of X and Y sperm. Used for sex selection


Human Chorionic Gonadotrophin (HCG): A protein hormone usually secreted by the chorionic villi of the placenta. Its presence in the maternal blood or urine indicates pregnancy.

HEPT (Hamster Test): Mixing of sperm with the egg of a hamster for the purpose of testing fertility. Any test material must be destroyed no later than the 2 cell stage.

HFE Act: The Human Fertilisation and Embryology Act 1990.

HFEA: Human Fertilisation and Embryology Authority.

HOS Test: Hypo-osmotic swelling test, used to test the integrity and behaviour of the cell membrane of the sperm tail.

Human Menopausal Gonadotrophin: A drug used to stimulate egg (oocyte) development in the ovary as part of superovulation.

Hysterectomy: The surgical removal of the uterus (womb).

Hysterosalpingogram: An x-ray of the fallopian tubes which involves the passage of dye through the tubes to see if they are obstructed.


Implantation: The process whereby an embryo, after travelling through the fallopian tube to the uterus, embeds itself in the lining of the uterus.

Impotence: Term used to describe the inability of a man to perform sexual intercourse or gain an erection.

Inner cell mass: A clump of cells growing within and to one side of the blastocyst from which the embryo develops.

Insemination: The placing of sperm in the female reproductive tract by artificial means. Can be performed using either freshly ejaculated sperm or sperm that has been frozen.

Intra Cytoplasmic Sperm Injection (ICSI): In conjunction with IVF, where a single sperm is directly injected, by a recognised practitioner, into the egg. A clinic may also use donor sperm or eggs.

Intra Uterine Insemination (IUI): Insemination of sperm into the uterus of a woman.

Intra vaginal culture (IVC): A method whereby sperm and aspirated oocytes are incubated together in a container held in a woman's vagina in order to effect fertilisation in vitro without the need for complex laboratory facilities.

In Vitro Fertilisation (IVF): Patient's eggs and her partner's sperm are collected and mixed together in a laboratory to achieve fertilisation outside the body. The embryos produced may then be transferred into the female patient.

In vitro: Performed outside the body (i.e. in the laboratory).

In vivo: Performed in the body.


Karyotype: The microscopic appearance of a set of chromosomes, including their number, shape and size.


Laparoscopy: Examination of the pelvic or other abdominal organs with a fibreoptic telescope inserted surgically below the naval. During laparoscopy, suction applied to the needle can be used in the recovery of eggs from follicles in the ovary.

Lavage: The removal of a fertilised egg or cleavage stage embryo from the womb before implantation by washing out the uterine cavity.

Licence: A legal document stipulating terms and conditions for which a centre may carry out a licensable fertility treatment at a specified premise.

Live birth rate: The number of live births achieved from every 100 treatment cycles commenced.

Live birth event: The delivery of one or more babies.

Luteinising Hormone (LH): Hormone released by the pituitary gland in response to Gonadotrophin Releasing Hormone (GnRH) production. Essential for development of eggs and sperm.


Menstrual period/Menstruation: The monthly bleed which takes place if no pregnancy occurs and is caused by the sloughing off of the lining of the womb.

Menstrual cycle: A cycle of approximately one month in the female during which the egg is released from an ovary, the uterus is prepared to receive the fertilised egg and blood and tissue are lost via the vagina if a pregnancy does not occur.

Metrodin: A commonly used fertility drug which is highly purified Follicle Stimulating Hormone (FSH). Used to stimulate the production of more than one follicle in IUI, DI and IVF.

Microsurgical Epididymal Sperm Aspiration (MESA): The technique wherby a small needle is used to extract relatively mature sperm from the epididymis.

Monozygotic: Derived from a single (mono) egg (zygote). Monozygotic twins form when one fertilised ovum separates into two identical zygotes.

Morula: The ball of cells which forms at about 3 ? 4 days after insemination of the egg, resulting from the cleavage of the fertilised ovum.

Multiple birth: The term used when a multiple pregnancy actually results in the birth of two or more babies.

Multiple birth rate: This is the percentage of all births in which more than one baby was born.


Nafarelin: A commonly used fertility drug which reduces hormone levels to almost zero so that the fertility cycle can be controlled more easily. Taken in the form of a nasal spray.

Neonatal death: The death of a baby within 28 complete days of delivery.

Nucleus: The part of a cell which contains the genetic material DNA.


Oestrogen/Oestradiol: Female sex hormone produced by the ovary. Levels fluctuate during the menstrual cycle.

Oligozoospermia: Low sperm count - less than twenty million sperm per millilitre. It can be severe - less than five million sperm per millilitre.

Oocyte: The female gamete (egg).

Ovary: The female reproductive organ in which oocytes are produced from pre-existing germ cells. The ovary also produces hormones.

Ovarian Hyperstimulation Syndrome (OHSS): A serious complication following stimulation of the ovaries with gonadotrophin drugs.

Ovulation: The release of an egg from a follicle in the ovary.

Ovum: The female gamete (egg).


Partial Zona Dissection (PZD): In conjunction with IVF, a small hole is made in the gelatinous coating of the egg using a small glass needle to assist sperm in reaching the outer egg membrane. A clinic may also use donor sperm or eggs.

Percutaneous Epididymal Sperm Aspiration (PESA): A sperm recovery technique whereby a fine needle is passed through the skin of the scrotum and into the epididymal region of the testes and sperm are withdrawn using gentle suction. Or, retrieving sperm directly from the coiled tubing outside the testicles that store sperm (epididymis) using a needle.

Peritoneal cavity: The cavity of the abdomen where the fallopian tubes and the uterus are situated

Perinatal Mortality Rate: Perinatal mortality is the total number of foetal deaths and neonatal deaths.

Pituitary: Gland in the brain which produces many hormones including Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH).

Polycystic Ovarian Syndrome (PCOS) : Condition where many small cysts form on the ovary and hormonal imbalances result which can cause infertility. Treatment is in the form of drugs or surgery.

Polymerase Chain Reaction: A process used in DNA analysis.

Pregnancy rate: The number of pregnancies achieved from every 100 treatment cycles commenced.

Preimplantation Genetic Diagnosis (PGD): In conjunction with IVF, where a recognised practitioner removes one or two cells from an embryo, for those cells to be tested for specific genetic disorders/characteristics before embryo transfer takes place.

Preimplantation Genetic Screening for Aneuploidy (PGS): In conjunction with IVF, where a recognised practitioner removes one or two cells from an embryo, for those cells to be tested to ensure they contain the correct number of chromosomes (known as euploidy) and not more or less than usual (known as aneuploidy). Normal embryos (euploidy) will be selected before embryo transfer takes place.

Primitive streak: Thickening in surface of embryos which results in the first clearly recognisable stage in embryonic development.

Profasi: Drug used in assisted conception to mature follicles and cause ovulation to occur. It consists of purified Human Chorionic Gonadotrophin.

Progesterone: Hormone produced by the ovary and by the corpus luteum after ovulation which encourages the growth of the lining of the womb.

Pro-nucleus: A small round structure(s) seen within the egg after fertilisation which contain the haploid sets of chromosomes (genetic material of each gamete) surrounded by a membrane. A normal fertilised egg should contain two pro-nuclei, one from the egg and one from the sperm.

Prostate Gland: A gland which secretes an alkali solution upon ejaculation which makes up a major part of the ejaculate.

Puregon: A commonly used fertility drug which consists of highly purified FSH and is used to stimulate the production of more than one follicle.




Selective reduction: The procedure in which one or more normal foetuses in a multiple pregnancy resulting from assisted conception are destroyed. The procedure may be hazardous to the remaining foetus(es).

Seminiferous tubules: Very long and convoluted tubules which make up the bulk of the testicles. It is here that sperm is produced.

Sex selection: The sex of an embryo is determined using PGD, in order to avoid sex-linked diseases.

Sperm: The gamete (or mature male germ cell) produced by the male, usually through ejaculation. Millions of sperm are present in each ejaculate and roughly half of these will carry X chromosomes, the other half carrying Y chromosomes. A single sperm is called a spermatozoon.

Sperm sorting: The separation of sperm carrying X chromosomes from those carrying Y chromosomes prior to fertilisation, in order to determine the sex of the offspring. Used for sex selection.

Spermatid: An immature sperm cell.

Stem cell: Reproduce indefinitely and have the capacity to develop (differentiate) into a large number of different cell types.

Stillbirth: The birth of a dead infant.

Stimulated cycle: A treatment cycle in which stimulation drugs are used to produce more eggs than usual in the woman's monthly cycle.

Stimulation drugs: Drugs used to stimulate a woman's ovaries to produce more eggs than usual in a monthly cycle; also known as superovulatory drugs.

Subzonal sperm insertion (SUZI): A technique whereby one or several sperm are injected directly through the zona pellucida (outer layer) of the oocyte.

Superovulation/stimulation: The medical stimulation of the ovary with hormones to induce the production of multiple egg-containing follicles in a single menstrual cycle.

Swim up: A technique for separating sperm, based on their ability to swim through a liquid.


Teratozoospermia: Poor sperm morphology (shape) which cause infertility.

Testicular Sperm Aspiration (TESA): This sperm extraction technique involves the insertion of a needle into the lower region of the testes and the removal of a small piece of testicular tissue.

Testicular Sperm Extraction (TESE): This sperm extraction technique involves the exposure of testicular tissue through a small cut in the scrotum and the removal of a small piece of testicular tissue. Or, retrieving sperm directly from the testis

Testis: Testicle or male gonad

Transvaginal aspiration: A method of egg recovery in which a needle is inserted through the top of the vagina into the ovary lining.

Transvaginal oocyte recovery: The female bladder is empty and a needle is passed through the vagina under ultrasound guidance in order to recover eggs.

Treatment cycle: One complete licensed treatment. Commences with administration of drugs or first insemination.

Trisomy: A syndrome reflecting the presence of three chromosomes of one type instead of the normal human chromosome number of two. An example is Trisomy 21 resulting in Down's syndrome.


Ultrasound: High frequency sound waves used to provide images of tissues, organs and other internal bodily structures.

Ultrasound-guided aspiration: A non-surgical, non-invasive method of egg recovery using ultrasound images to guide the path of the oocyte recovery needle.

Unstimulated cycle: No drugs are given to stimulate egg production. Also known as a natural cycle.

Uterus: The female womb in which the embryo develops.


Varicocele: A varicose vein on the testicles. It is thought that these may cause overheating of the testicle and be detrimental to sperm production.

Vas Deferens: Pair of tubes which connect the epididymis to the urethra and transport sperm during ejaculation.





Zona drilling: The use of chemical to dissolve the gelatinous coating of the egg leaving a hole through which the sperm can enter. A clinic may also use donor sperm or eggs.

Zona Pellucida: The transparent membrane or shell surrounding the oocyte (egg).

Zygote: The cell formed as a result of fertilisation.

Zygote Intra-Fallopian Transfer (ZIFT): The transfer of embryos to the fallopian tubes for purposes of achieving a pregnancy. Embryos are transferred at the fertilised egg (one cell embryo) stage.

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