Glossary
The words that get used in a fertility clinic as if everyone already knows them. A first appointment runs at about twice the speed anyone can follow, and most people leave with a list of terms they nodded at. Each entry here gives the plain meaning first, then the context: where you will meet the word, what it actually measures, and which pages go deeper.
Pay particular attention to the entries about success rates. There are several ways to report whether fertility treatment works, and each gives a different number. Those entries explain what each figure counts, so you can compare like with like.
I add terms as they come up in the treatment guides, so this list grows. If a word you have hit is not here, tell me and I will write it.
Terms A–Z
A
AMH
The blood test that estimates how many eggs are left. A reliable guide to how you will respond to stimulation drugs.
Antral follicle count
The ultrasound tally of small resting follicles early in the cycle. Predicts how many eggs a stimulated cycle will yield, not egg quality.
Azoospermia
No sperm in the ejaculate. Splits into a blockage, which is usually solvable, and reduced production, where retrieval finds sperm in around half of men.
B
Blastocyst
A day five or six embryo, already sorted into baby and placenta. The stage at which the strongest embryos are chosen for transfer.
D
Day 21 progesterone
A blood test taken about a week before your period is due. A high progesterone level means you ovulated that cycle.
Donor anonymity
Whether a donor's identifying details are recorded and released at adulthood. Decided by the country of treatment.
Donor eggs
Eggs from another woman, fertilised with your partner's sperm or donor sperm. The odds follow the donor's age rather than yours.
Donor sperm
Sperm from a bank or a known donor, used for insemination or IVF. Screened, quarantined, and governed by the law where you are treated.
E
Egg vitrification
The flash-freezing step in egg freezing, and the name many clinics use for the whole business of banking unfertilised eggs.
Embryo adoption
Using embryos another couple created and no longer need. The term is common in the United States; most clinics say embryo donation.
Embryo freezing
Fertilising the eggs first and storing embryos. You know more per unit stored than with eggs, but it ties them to that partnership.
Embryo grading
The code describing how an embryo looks, used to rank which goes back first. A good guide across a batch, less so for any single embryo.
Endometrium
The lining of the uterus, built by oestrogen and made receptive by progesterone. Measured before a transfer, and why some get postponed.
Endometriosis
Womb-like tissue growing in the pelvis, causing pain and scarring. Keyhole surgery and IVF are both effective routes to pregnancy.
F
FET
Frozen embryo transfer. Thawing an embryo from an earlier collection and placing it in the uterus, with no stimulation and no collection.
Freeze-all
A cycle where every embryo is frozen and none transferred fresh, so the uterus is not asked to accept one while the ovaries are swollen.
H
HSG
Hysterosalpingogram. The X-ray dye test that checks whether the fallopian tubes are open and the cavity of the uterus is a normal shape.
HyCoSy
The ultrasound version of the tubal dye test, using contrast fluid rather than X-ray. Same question about the tubes, no radiation.
Hydrosalpinx
A blocked fallopian tube swollen with fluid. Removing or clipping it before IVF gives embryos a better chance of implanting.
I
ICSI
IVF with a single sperm injected directly into each mature egg. Invented for male factor, and for male factor a genuine solution.
IUI
Washed sperm placed into the uterus around ovulation. Affordable and gentle, and a good first step where a tube is open and the sperm is reasonable.
IVF
In vitro fertilisation. Injections to grow a batch of eggs, collection under sedation, fertilisation in the laboratory, one embryo put back.
L
Live birth rate
The proportion of attempts that ended with a baby. The most useful success figure, once you know what it counts from.
M
Micro-TESE
Searching the testicle under high magnification for the pockets still producing sperm. The technique for non-obstructive azoospermia.
O
OHSS
Ovarian hyperstimulation syndrome. The ovaries over-respond and leak fluid into the abdomen. Mild is common, severe is uncommon and urgent.
Oocyte cryopreservation
The clinical name for egg freezing. An IVF cycle that stops after collection, with the mature eggs frozen unfertilised.
Ovarian reserve
Roughly how many eggs are left, estimated from an AMH blood test and an antral follicle count. A measure of quantity, not quality.
Ovarian tissue freezing
Removing and freezing a piece of ovary rather than eggs. Used mainly before cancer treatment, and the only option before puberty.
Ovulation predictor kit
The home urine test that picks up the LH surge a day or so before ovulation, marking the start of the fertile window.
P
PESA
Percutaneous epididymal sperm aspiration. A needle draws sperm from behind a blockage, usually under local anaesthetic.
PGT-A
Chromosome testing of embryos before transfer. It helps the strongest embryo go first, which can mean fewer failed transfers.
S
Seminogram
Another name for a semen analysis. Volume, sperm count, how many are moving and how many are normally shaped.
Sperm banking
Freezing and storing sperm, most often before cancer treatment, testicular surgery, gender-affirming hormones or a vasectomy.
Stimulation
The eight to fourteen days of daily injections that grow a batch of follicles, monitored by scans and ended by a precisely timed trigger.
T
TESE
Testicular sperm extraction. Taking small pieces of testicular tissue and searching them for sperm to use in ICSI.
Two-week wait
The nine to fourteen days between transfer and a meaningful pregnancy test. Normal life is fine, and a plan for the days makes it easier.
V
Vitrification
Flash-freezing that turns cell water glassy instead of icy. It is why frozen eggs and embryos now survive the thaw and frozen cycles work.
Varicocele
Swollen veins in the scrotum that can warm the testicle and lower sperm quality. One of the few male causes that surgery can correct.
New to fertility treatment?
The Start Here guide walks through the tests, the treatments, the order they usually come in, and how to read the success figures.
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