What do IVF, ICSI, FET and the rest actually mean?
A first fertility appointment runs at about twice the speed anyone can follow. In forty minutes you will hear AMH, antral follicle count, IUI, ICSI, blastocyst, FET, PGT-A and a success rate, and you will nod at every one of them. Then you get to the car park and realise you could not define a single word.
That is not a failure of attention. The people saying these words use them fifty times a day. What follows is each one explained once, in roughly the order you meet it, and I have put the most important one last on purpose. It is not a treatment. It is the difference between a pregnancy rate and a live birth rate, and once you understand it you can read any clinic's figures with confidence.
The testing words
AMH is anti-Müllerian hormone, a blood test. It estimates how many eggs are left, which is called your ovarian reserve. It helps to know its limits. AMH is a rough count, not a quality score, and it does not predict whether you can conceive naturally. A low AMH in your early thirties is a reason to get on with things, not a verdict.
AFC, antral follicle count, is the ultrasound version of the same question. A sonographer counts the small resting follicles on each ovary. AMH and AFC are usually read together, because either one on its own moves around more than you would like.
FSH, LH, oestradiol and progesterone are the cycle hormones, drawn on particular days because the numbers mean different things at different points. Progesterone a week before your period is asking whether you ovulated. FSH early in the cycle is asking how hard your body is having to shout at the ovaries.
HSG is the X-ray dye test that checks whether the fallopian tubes are open. The ultrasound version is HyCoSy, and clinics vary in which they use. See tubal patency testing, and the fertility testing hub for the whole first round.
On the male side, the whole first round is one test: a semen analysis. Volume, count, how many are moving, how many are shaped normally. It is the cheapest thing in fertility medicine and one of the most useful, so it is worth asking for it at the very start, alongside the female partner's tests.
The treatment words
IUI is intra-uterine insemination. Sperm is prepared in the lab and placed directly into the uterus around ovulation, often with mild stimulation to make the timing reliable. It needs at least one open tube and reasonable sperm. The odds per cycle are modest and they fall with age, so it is normally tried a few times rather than indefinitely. See IUI.
IVF is in vitro fertilisation, which is Latin for "in glass". Injections for roughly eight to fourteen days to grow several follicles at once, egg collection under sedation, eggs and sperm put together in the lab, a few days of embryo growth, then one embryo placed in the uterus. The IVF guide walks through it properly.
ICSI is intracytoplasmic sperm injection, and it is a step inside IVF rather than an alternative to it. Instead of leaving eggs and sperm to find each other, an embryologist injects one sperm into each mature egg under a microscope. It was invented for male factor, and for male factor it is a genuine solution. Where there is no male factor, conventional fertilisation usually does just as well for less, so it is worth asking why it is being suggested. See ICSI.
The laboratory words
After fertilisation the embryos are grown for a few days, and the vocabulary gets microscopic. A day 3 embryo has around eight cells. A blastocyst is where it gets to on day five or six: a hundred or more cells, already sorted into the part that becomes the baby and the part that becomes the placenta. Not every embryo makes it that far, and that attrition is normal rather than a sign something went wrong.
Grading is the embryologist's description of how an embryo looks. It is a useful shorthand rather than a prediction, and plenty of unremarkable-looking embryos become babies.
Vitrification is the flash-freezing method that replaced slow freezing, and it is the reason frozen cycles work as well as they now do.
PGT-A is preimplantation genetic testing for aneuploidy: a biopsy of a few cells from a blastocyst to check the chromosome count. Its value is still debated, and it suits some people more than others. It can reduce the number of transfers needed for some people, particularly at older ages. What good trials have struggled to show is that it produces more babies per cycle started, and in younger patients it may set aside embryos that would have worked. If it is offered to you, ask what it would change about your plan. See PGT-A.
OHSS, ovarian hyperstimulation syndrome, is the main risk of the stimulation drugs: the ovaries overreact, fluid shifts, and in the severe form it needs hospital treatment. Severe cases are uncommon now, because protocols changed to prevent it, including freezing everything and transferring later. Bloating after egg collection is expected. Rapid weight gain, breathlessness or serious pain is a phone call to the clinic, tonight, not in the morning.
FET is frozen embryo transfer: thawing an embryo from a previous cycle and transferring it, either in your natural cycle or on medication. Most clinics now freeze routinely and transfer later, which is why one egg collection can mean several chances. See frozen embryo transfer.
The one that matters
Which brings us to the success rate, and the reason I wrote this.
There is no single agreed way to report fertility success, and the way a clinic chooses changes the number enormously. Clinical pregnancy per transfer is the highest version: it counts pregnancies rather than babies, and it counts only the cycles that reached a transfer, leaving out cycles cancelled before egg collection or with nothing ready to transfer. Live birth per cycle started counts every cycle that began, and it counts babies. The gap between those two figures, for the same clinic in the same year, can be very wide. The live birth rate entry in the glossary sets out every version and what each leaves out.
So the question to ask is one sentence: is that live birth per cycle started, for women in my age band, using their own eggs? Age matters more than any other variable, and a clinic average reflects the mix of patients that clinic treats, so the age-band figure is the one that applies to you.
A clear, specific answer tells you something good about the place. It is the one piece of arithmetic in this whole vocabulary worth doing yourself, and now you know how.
You do not need to memorise any of the rest. Ask what a word means the moment you hear it, every time. Nobody in that room thinks less of you for it, and the ones worth being treated by will be glad you asked.
This is general information, not medical advice. If you are at the beginning, start here.
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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