Glossary of fertility terms
Abandoned cycle: An IVF or ICSI treatment cycle which is cancelled after ovarian stimulation has begun but before egg collection.
Abstinence: The number of days since last ejaculation.
Adhesions: Scar tissue which forms following surgery, infection or trauma and which causes pelvic organs to stick together.
Anosmia: Inability to smell, may be associate with some azoospermic conditions
Antisperm antibodies: The immune system of some patients may recognise sperm as ‘foreign’ cells and produce antibodies against them. If this happens the antibodies can coat the outside of the sperm which may prevent the sperm from attaching to the egg and therefore inhibit fertilisation.
Assisted hatching: A technique used to help the embryo escape from its zona pellucida (shell). An embryo needs to hatch before implantation can occur.
Asthenozoospermia: Terminology used to describe subfertility where sperm have reduced motility (movement): less than 50% motile sperm or with sperm showing slow progression.
Azoospermia: The disorder where the ejaculated semen does not contain any sperm cells; this may be due to a blockage (as in vasectomy) or a failure in production of the sperm.
Blastocyst: Refers to an embryo that has been developing for 5 – 6 days following fertilisation.
Cervix: A narrow passage connecting the vagina to the womb (uterus)
Chromosomes: Chromosomes are thread-like bodies of DNA which contain the genetic code in genes. Half of the chromosomes will be inherited from the mother and the other half from the father.
Chlamydia: A sexually transmitted disease that may affect both males and females; there may be few symptoms and if left untreated the disease can often lead to infertility.
Cleavage: Cell division in early embryos necessary for development
Clomiphene: An anti-oestrogen drug that helps to stimulate the production of follicles, often used to treat anovulation and in DI and IUI cycles.
Congenital malformations: Malformations seen at birth (birth defects) due to inherited or environmental causes.
Counselling: Couples seeking fertility sometimes require emotional support to help them through what can be a difficult time. A counsellor will help couples to understand the implications of treatment and its consequences.
Cryopreservation: Embryos, sperm and eggs (only offered by some clinics) can be frozen and stored in liquid nitrogen at minus 196 degrees for use at a later date. They are passed through a series of specially designed solutions which help to protect the cells from damage during the freezing and thawing processes.
DI – Donor Insemination: Donor sperm is introduced into the vagina, cervix or uterus using a catheter. It may be used to treat couples where the male partner is unable to produce his own sperm, single sex couples, or single women.
Donated embryos: Embryo donation provides a chance for couples for whom no treatment is available to help them. Fertility is an issue for both partners, hence the only chance of a pregnancy is through embryo donation.
Donated eggs: If a woman is unable to produce eggs of her own, or is producing eggs of poor quality, it may be possible to use eggs that have been donated from another fertile woman.
Donated sperm: Semen donated by sperm donors and frozen before being used to treat couples when the male partner is unable to produce adequate sperm. May also be used to treat single women or same-sex couples.
Donor: A person or couple who chooses to provide their eggs, sperm or embryos for use by others. All UK donors must be screened for known infectious diseases, and have no legal right or obligation to any child born as a result of treatment given in a UK licensed clinic
Ectopic pregnancy: Where a pregnancy occurs outside the uterus, usually in the fallopian tubes, and may occur both in natural pregnancies and those following assisted conception.
Egg (oocyte): The gamete produced in the ovary of a woman, generally one egg is made each monthly cycle
Egg collection (retrieval): Minor surgical procedure to collect the eggs produced by the ovaries (usually after ovarian stimulation). Mostly done using ultrasound to visualise the ovaries and follicles containing the eggs, but may be done using a laparoscope. The fluid-filled follicles are drained with a needle and the fluid examined in the laboratory for eggs.
Egg donor: A woman who donates her eggs for the treatment of others.
Ejaculation: The release of seminal fluid following sexual arousal.
Embryo: An embryo is formed following successful fertilisation of an egg by a sperm.
Embryo grading: In the laboratory embryos can be ‘graded’ according to their appearance. The number, shape and symmetry of the cells and any fragmentation is assessed and compared to the expected stage of development; this may give an indication of embryo quality and the potential of an embryo to develop into a pregnancy.
Embryo transfer: Procedure of replacing embryos in the uterus
Endometriosis: A condition in which small parts of endometrium, which usually provides the lining of the womb, grow in other places within the pelvic cavity. The severity of endometriosis varies depending upon the areas and amount of endometrial growth; it can cause bleeding, pelvic pain and problems with fertility.
Endometrium: The lining of the womb which develops each month ready to receive the implanting embryo, but shed in a period of no implantation occurs.
Epididymis: sperm storage and transport tube in the testis
Fallopian tubes (Oviducts): The fallopian tubes connect together the ovaries and the uterus. In a natural cycle this is where the sperm and egg meet and fertilisation occurs.
Fertilisation: Occurs when an egg and sperm meet successfully to form an embryo.
Folic Acid: A dietary supplement that is advisable for women planning a pregnancy and those in the early stages of pregnancy that helps to reduce the chances of neural tube defects such as spina bifida.
Follicles: The small fluid filled sacs that develop on the ovaries and usually contain eggs.
FSH – Follicle Stimulating Hormone: A hormone produced by the Pituitary Gland in the brain that stimulates the production of follicles containing eggs on the ovaries. The drugs that are given during IVF and ICSI cycles to stimulate the production of lots of eggs contain FSH.
Gamete: A Gamete is the generic term used to describe egg and sperm cells.
HFEA – Human Fertilisation and Embryology Authority: The HFEA is a body that was set up in 1991 following the 1990 Act of Parliament to regulate all assisted conception procedures in the United Kingdom . All clinics providing assisted conception treatments in UK are inspected and licensed by the HFEA and must work within the HFEA Code of Practice.
Hormone profile: A blood test used to measure the levels of certain hormones in the blood that are related to reproductive function.
HyCoSy: (Hysterosalpingo contrast sonography) is an outpatient procedure which uses ultrasound to investigate the cavity of the uterus and the Fallopian tubes.
Hysterosalpingogram: A diagnostic procedure used to assess whether the fallopian tubes are blocked or open. A dye is injected into the tubes, this dye can then be picked up on an x-ray and will show whether the tubes are patent (open).
ICSI – Intra-Cytoplasmic Sperm Injection: An individual sperm is injected directly into the middle of an egg using a sophisticated microscope and micromanipulation tools. This procedure may increase the chances of fertilisation occurring in cases of male factor infertility.
Implantation: occurs when an embryo attaches to the endometrium, or lining of the womb.
Inner cell mass: The area of cells inside a blastocyst that will go on to form the developing foetus
Insemination: the introduction of sperm in the proximity of the oocyte/s (eggs)
IUI – Intra-Uterine Insemination: A small volume of sperm sample that has been prepared in the laboratory is introduced into the uterus through the cervix using a fine catheter (tube)
In vitro: Literally meaning ‘In-Glass’ or in the laboratory.
In vivo: Meaning inside the body.
IVF – In Vitro Fertilisation: Mixing of eggs and sperm to achieve fertilisation outside the body.
Karyotype: microscopic image of a set of chromosomes so their number and size can be checked.
Laparoscopy: A surgical procedure in which a telescopic camera (laparoscope) is passed through a small incision in the navel to look at the pelvic organs; may be used to investigate causes of infertility.
LH – Luteinising Hormone: LH is involved both in egg and sperm production. In women it helps the developing egg to ripen and reach the right stage of maturity for fertilisation to occur and be released. In men it stimulates the testicles to produce testosterone. A sharp rise in LH is detected in ovulation prediction tests.
Live birth rates: The number of live births per 100 treatment cycles.
Male factor: Problems with sperm production can be classed together as Male Factor infertility. These may include low sperm count, high levels of abnormal sperm, problems with swimming patterns, a vasectomy or failed vasectomy reversal or blockages.
Morphology: Most often used to describe the shape of sperm but can also be used to describe the appearance of the cells within an embryo.
Motility: A term used in semen analysis to describe the movement of sperm. The percentage of sperm swimming is assessed and the speed with which they are progressing is measured.
Multiple pregnancy: A pregnancy in which there is more than one foetus developing. Fertility treatment may result in a multiple pregnancy if more than one embryo is transferred or if more than one follicle develops during ovulation induction.
Nucleus: Part of a cell which contains the chromosomes.
Oestradiol (Oestrogen): The female sex hormone that is produced by the ovaries.
OHSS – Ovarian Hyperstimulation Syndrome: The drugs that are given to stimulate the production of eggs for a treatment cycle, although carefully prescribed, may occasionally cause the complication of OHSS. This is where too many follicles and eggs are produced and may mean that a cycle has to be abandoned until symptoms subside, or if egg collection proceeds the embryos may all be frozen until the ovaries have recovered and it is safe to continue treatment.
Oligozoospermia: Terminology for a condition when the semen sample has a reduced concentration of sperm; the count is less than 20 million sperm per millilitre of ejaculate.
Ongoing pregnancy: Refers to those pregnancies confirmed by ultrasound scan
Oocyte (egg): The gamete produced in a woman’s ovaries; generally one egg is made each monthly cycle
Ovary: female reproductive organ where eggs are produced in follicles
Ovulation: This is where a ripe egg is released by the ovary and begins it journey down the fallopian tube towards the uterus.
OI – Ovulation Induction: Drugs are used to stimulate the ovaries to produce and release one or more eggs prior to insemination or timed intercourse to maximise the chance of conception.
PID – Pelvic Inflammatory Disease: Sexually transmitted infections may cause inflammation and damage to the reproductive organs and lead to difficulties with fertility.
PESA – Percutaneous Sperm Aspiration: A fine needle is passed into the epididymis (the tubes in the testes which store sperm); the fluid is aspirated and examined in the laboratory for the presence of sperm.
PCOS – Polycystic Ovarian Syndrome: A complex condition in which the ovaries produce many small cysts or follicles which can cause a hormone imbalance, problems with ovulation and consequently with fertility.
Placenta: The placenta provides the connection between the mother and the developing foetus
Pregnancy rate: number of pregnancies for every 100 treatment cycles started.
Progesterone: Female hormone responsible for preparing the lining of the womb for pregnancy. If pregnancy does not occur, progesterone levels fall and the lining of the womb is shed (a ‘period’).
Progression: Refers to the direction and speed with which the sperm are swimming.
Quality control: System to ensure safe and effective delivery of all processes used in treatment of patients
Retrograde ejaculation: The products of ejaculation are not released normally but are deposited in the bladder. It may then be possible to isolate the sperm cells from the urine in the laboratory.
Semen analysis: Used to assess the parameters in seminal fluid produced at the time of ejaculation. The number of sperm, how many of the sperm are swimming (and how quickly) and the shape of the sperm are assessed. Other values such as the volume, the pH, viscosity and the presence of antisperm antibodies are measured.
Sex selection: technique offered by some clinics to determine the sex of an embryo before replacement. Used to avoid transferring embryos which may carry sex-linked diseases.
Sperm: the male gamete produced in the testes.
Sperm count: The number of sperm is counted under the microscope; a normal count should be more than 20 million/ml.
Sperm donor: A man who donates his sperm for use in treatment by others.
Stimulation/superovulation: Process of using drugs to induce the ovaries to produce multiple follicles.
Surgical Sperm Retrieval: If there is a blockage in the sperm transport ducts that prevents sperm from being released during ejaculation it may be possible to extract the sperm directly from the testes using PESA or TESE during a minor procedure.
Surrogacy: The act of getting pregnant and carrying a child on behalf of someone who for medical reasons cannot carry a pregnancy themselves.
Take home baby rate: The number of cycles that result in a live birth per 100 treatment cycles.
Teratozoospermia: During semen analysis the shape of the sperm head, midpiece (neck) and tail is compared to a ‘normal’ sperm model and the sperm classed as abnormal or normal. Teratozoospermia is a term used to describe subfertility linked to semen with raised levels of abnormally shaped sperm (greater than 85%).
TESE – Testicular Sperm Extraction: A small sample of testicular tissue is taken using a needle during a minor operation. This tissue is then processed in the laboratory to extract any sperm that are present.
Testis (testicle): male reproductive organ where sperm are produced
Testosterone: The male sex hormone that is produced by the testicles.
Trophectoderm: The layer of cells that form around the outside of a blastocyst on day 5 or day 6 of development. These cells eventually form the placenta and are responsible for implantation in the uterus.
Ultrasound scan: High frequency waves are used to see inside the body and allow doctors and nurses to visualise structures such as the uterus and the ovaries. Used to monitor development of follicles during ovarian stimulation, and to ‘see’ the follicles during egg collection, as well as to confirm the presence of an early pregnancy.
Uterine receptivity: This refers to the readiness of the lining of the womb (the endometrium) for an embryo to implant and pregnancy to begin. It is only in peak condition for implantation for a short time in each monthly cycle.
Uterus: The uterus or womb is the female organ which supports the growth of an embryo and eventually a baby.
Vas deferens: Sperm transport duct in the testis.
Welfare of the Child: social and ethical aspects used in assessing the well-being of any child (new or existing) under 18 who may be affected by fertility treatment
X chromosome: The X chromosome contains female genes. A maternal X chromosome is always passed on by the egg, and the fertilising sperm may pass on another X chromosome, or a Y chromosome.
Y chromosome: The Y chromosome contains male-specific genes from the father. Sperm carry X or Y chromosomes: if an egg is fertilised by a sperm that has a Y chromosome a boy will be born, if the sperm has an X chromosome a girl will be born.
Zona pellucida: The zona pellucida is the protective shell-like coating of the egg.
Zygote: Name for the very early one-cell embryo formed when the egg and sperm fertilise.