A guide to the language used within fertility treatment

Assisted Conception Unit
When an egg is not released from the ovary, each cycle
The complete absence of sperm in the male ejaculate
An embryo that has developed for five to six days after fertilisation
Body Mass Index - your weight (in kg) divided by the square of your height (in metres squared)
Congenital Bilateral Absence of the Vas Deferens. A condition in men born without the tubes which carry sperm from the testicle into the ejaculate
The narrow passage at the lower end of the uterus (womb), connecting to the vagina
A threadlike structure of DNA containing genes, which carry genetic information
Down regulation
Part of infertility treatment, using medication, which makes a woman's ovaries temporarily inactive to prevent the release of eggs before they are collected
Donor insemination. The introduction of donor sperm into the uterus (womb)
Ectopic pregnancy
A pregnancy, which implants outside the uterus (womb)
Gamete produced by a woman during her monthly cycle
A fertilised egg
The lining of the womb, which grows and sheds during a normal menstrual cycle and which supports a pregnancy
A female condition in which endometrial cells, which normally line the uterus, implant around the outside of the uterus and/or ovaries, causing pain, internal bleeding and reduced fertility
The area above the testicle where sperm are stored
Fallopian tubes
The tubes on either side of the uterus where the sperm should fertilise the egg and the embryo should travel through to the uterus (womb)
The penetration of an egg by a sperm resulting in the formation of an embryo
Benign (non-cancerous) overgrowth of the muscle layer of the womb. Can be linked with fertility problems if the fibroids grow into the lining of the womb or are very large
A collection of fluid within the ovary, which usually contains an egg if it grows to a certain size
Follicle Stimulating Hormone. The hormone produced by the brain to stimulate the ovary to make one or more follicles grow. Is available in synthetic form to use in fertility treatment. Gametes eggs or sperm
Human Chorionic Gonadotrophin - an injection given to a woman having IVF to mature the eggs. Also indicates pregnancy
Human Fertilisation and Embryology Authority. A Government body which regulates clinics performing IVF and other treatments using sperm, eggs and embryos
Hysterosalpingogram. An X-ray test involving the injection of dye to check if the fallopian tubes are open
Intracytoplasmic Sperm Injection. When a single sperm is injected into a single egg
Intra Uterine Insemination. A fertility treatment which places a sample of sperm into the uterus and conception occurs naturally inside the body
In Vitro Fertilisation – a treatment process where the female is stimulated to produce eggs, which are retrieved under sedation. Eggs and sperm are then mixed together in a laboratory dish to achieve fertilisation. Any fertilised eggs (embryos) are then transferred back into the womb
In vivo
In the body
In vitro
In a laboratory setting
Multiple pregnancy
Two or more babies
Female sex hormone produced by the ovary. Levels change throughout the cycle
The female gamete (egg)
The female reproductive organ, which produces egg(s) from hormone stimulated follicles
Ovarian Hyper Stimulation Syndrome. Can occur if there are a large number of follicles/eggs, causing abdominal bloating, pain, nausea and breathlessness
Polycystic Ovarian Syndrome. A condition where multiple, small follicles arrange themselves around the outside of the ovary. Can be an isolated ultrasound finding but also associated with hormone imbalances and irregular ovulation. Worsened by excess weight
Percutaneous Epididymal Sperm Aspiration. A fine needle is passed into the epididymis, under local anaesthetic and sedation to find sperm in men where there is a blockage between production in the testicle and appearance in the ejaculate
Preimplantation Genetic Diagnosis. The removal of one or two cells from an embryo to test for genetic diseases. Only unaffected embryos are transferred
Ejaculated sperm
Male gametes
Testicular Sperm Aspiration. A sperm extraction technique, which involves inserting a needle into the testicle to remove testicular tissue
Testicular Sperm Extraction. A sperm extraction technique, which involves making a small cut in the scrotum and the removal of a small amount of testicular tissue
A female organ, also known as the womb
Zona Pellucida
The outer coating of the egg. Embryos/fertilised eggs have to 'hatch' out of this before they can implant

NHS Backing

Guy's and St Thomas' is a world renowned NHS Foundation Trust Hospital.

Read more

Funding and costs

Understand all of the funding options available to you.

Read more

What to expect

Helping you understand the process involved in receiving fertility treatment.

Read more

Meet the team

Meet our team of dedicated and expert professionals.

Read more