A guide to the language used within fertility treatment

ACU
Assisted Conception Unit
Anovulation
When an egg is not released from the ovary, each cycle
Azoospermia
The complete absence of sperm in the male ejaculate
Blastocyst
An embryo that has developed for five to six days after fertilisation
BMI
Body Mass Index - your weight (in kg) divided by the square of your height (in metres squared)
CBAVD
Congenital Bilateral Absence of the Vas Deferens. A condition in men born without the tubes which carry sperm from the testicle into the ejaculate
Cervix
The narrow passage at the lower end of the uterus (womb), connecting to the vagina
Chromosome
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
DI
Donor insemination. The introduction of donor sperm into the uterus (womb)
Ectopic pregnancy
A pregnancy, which implants outside the uterus (womb)
Egg
Gamete produced by a woman during her monthly cycle
Embryo
A fertilised egg
Endometrium
The lining of the womb, which grows and sheds during a normal menstrual cycle and which supports a pregnancy
Endometriosis
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
Epididymis
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)
Fertilisation
The penetration of an egg by a sperm resulting in the formation of an embryo
Fibroids
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
Follicle
A collection of fluid within the ovary, which usually contains an egg if it grows to a certain size
FSH
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
HCG
Human Chorionic Gonadotrophin - an injection given to a woman having IVF to mature the eggs. Also indicates pregnancy
HFEA
Human Fertilisation and Embryology Authority. A Government body which regulates clinics performing IVF and other treatments using sperm, eggs and embryos
HSG
Hysterosalpingogram. An X-ray test involving the injection of dye to check if the fallopian tubes are open
ICSI
Intracytoplasmic Sperm Injection. When a single sperm is injected into a single egg
IUI
Intra Uterine Insemination. A fertility treatment which places a sample of sperm into the uterus and conception occurs naturally inside the body
IVF
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
Oestrogen
Female sex hormone produced by the ovary. Levels change throughout the cycle
Oocyte/Ovum
The female gamete (egg)
Ovary
The female reproductive organ, which produces egg(s) from hormone stimulated follicles
OHSS
Ovarian Hyper Stimulation Syndrome. Can occur if there are a large number of follicles/eggs, causing abdominal bloating, pain, nausea and breathlessness
PCOS
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
PESA
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
PGD
Preimplantation Genetic Diagnosis. The removal of one or two cells from an embryo to test for genetic diseases. Only unaffected embryos are transferred
Semen
Ejaculated sperm
Sperm
Male gametes
TESA
Testicular Sperm Aspiration. A sperm extraction technique, which involves inserting a needle into the testicle to remove testicular tissue
TESE
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
Uterus
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

What to expect

Helping you understand the process involved in receiving fertility treatment.

Read more

Our history

Find out why we are the trusted choice for a wealth of patients.

Read more

NHS Backing

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

Read more

Meet the team

Meet our team of dedicated and expert professionals.

Read more