Fertility Treatment Terms: A Plain-Language Glossary

Fertility clinics use a lot of abbreviations, and being handed a plan full of them is disorienting. This is a plain-language glossary of the terms you are most likely to meet, grouped by where they come up. If a term you have been given is not here, ask us to explain it: you are entitled to understand your own treatment plan, and a good clinic will not mind being asked twice.

Treatments

• ART, assisted reproductive technology. The umbrella term for treatments that assist conception, including IVF, ICSI and egg freezing. Our overview of the available treatments covers each.
• IUI, intrauterine insemination. Prepared sperm placed into the uterus around ovulation. Fertilization still happens inside the body.
• IVF, in vitro fertilization. Eggs collected and combined with sperm in the laboratory; an embryo is transferred later.
• ICSI, intracytoplasmic sperm injection. IVF where one sperm is injected directly into each egg. Used mainly for male factor infertility.
• OI, ovulation induction. Medication to prompt the ovaries to release an egg, used where ovulation is irregular or absent.
• TESA, PESA, TESE. Ways of collecting sperm directly from the testicle or epididymis where there is none in the ejaculate.

During a cycle

• Stimulation. The phase of daily injections encouraging several follicles to mature, usually around 10 to 14 days.
• Follicle. The fluid-filled sac in the ovary containing an egg. Scans count and measure follicles, not eggs directly.
• Trigger injection. Given when follicles reach the right size, to complete egg maturation. Egg collection follows roughly 36 hours later.
• Egg retrieval or egg collection. The procedure collecting eggs from the ovaries, done with anesthesia.
• OHSS, ovarian hyperstimulation syndrome. An over-response to stimulation. Report severe bloating, significant pain, breathlessness or reduced urine output rather than waiting.
• Freeze-all. Freezing all embryos rather than transferring in the same cycle, often for safety or timing reasons. Not a setback.

Embryos and transfer

• Blastocyst. An embryo at day five or six of development, the usual stage for transfer or freezing.
• Embryo transfer. Placing an embryo into the uterus. Quick, and usually without sedation.
• FET, frozen embryo transfer. Transferring a previously frozen embryo in a later cycle.
• eSET, elective single embryo transfer. Transferring one embryo deliberately, to avoid the risks of a twin pregnancy. See how many embryos to transfer.
• Vitrification. The rapid freezing method used for eggs and embryos.
• Endometrium. The uterine lining, where an embryo implants. Its thickness is checked before transfer.

Tests and results

• AMH, anti-Mullerian hormone. Reflects how many eggs remain. It predicts response to stimulation, not whether you can conceive. See low AMH.
• AFC, antral follicle count. The number of small follicles visible on ultrasound, used alongside AMH.
• FSH and LH. Hormones that drive follicle development and ovulation.
• Semen analysis. Measures count, motility, morphology and vitality. See what it measures.
• Azoospermia. No sperm in the ejaculate. It does not always mean no sperm is being produced.
• Motility and morphology. How well sperm move, and their shape.
• PGT-A, PGT-M, PGT-SR. Tests on embryos: chromosome number, a specific single-gene condition, and structural rearrangements respectively. See the differences.

Terms used about results

• Per cycle started versus per transfer. Two different denominators for a success rate. Per transfer excludes cycles that never reached transfer, so it looks higher. Always ask which is being quoted.
• Clinical pregnancy versus live birth. A clinical pregnancy is a pregnancy seen on scan. A live birth is a baby. Live birth is the figure that matters.
• Cumulative. Across several cycles rather than one, so a cumulative rate will always look better than a per-cycle one.

Those three distinctions are the ones most often blurred when success rates are quoted, which is why they are worth knowing before you compare clinics.

We at Millennium IVF Clinic will explain any term in your own plan. You can arrange a consultation with our team.