IVF Glossary
Understanding IVF terminology can feel overwhelming. This glossary explains common terms you will encounter on your journey.
- AFC
- Antral Follicle Count, an ultrasound measurement of small follicles visible in both ovaries, used to estimate ovarian reserve.
- Agonist Protocol
- IVF stimulation protocol using GnRH agonist (e.g., Lupron) to suppress the pituitary gland before and during stimulation.
- AMH
- Anti-Mullerian Hormone, a blood test measuring ovarian reserve. Higher values generally indicate more eggs remaining.
- Antagonist Protocol
- IVF stimulation protocol using GnRH antagonist medications to prevent premature ovulation during the stimulation phase.
- Baseline Ultrasound
- Transvaginal ultrasound performed early in a cycle to check for cysts and count antral follicles before starting medications.
- Beta (hCG)
- Blood test measuring levels of the pregnancy hormone human chorionic gonadotropin (hCG). A rising beta confirms early pregnancy.
- Blastocyst
- A Day 5 or Day 6 embryo that has developed to the stage with a fluid-filled cavity and two distinct cell groups. Blastocysts have higher implantation rates than Day 3 embryos.
- Cryopreservation
- The process of freezing eggs, sperm, or embryos at ultra-low temperatures for future use. Modern vitrification makes survival rates very high.
- Day 3 Transfer
- Embryo transfer performed three days after egg retrieval, when embryos are at the 6-8 cell cleavage stage.
- Day 5 Transfer
- Embryo transfer at the blastocyst stage, five days after egg retrieval. Generally associated with higher implantation rates than Day 3 transfer.
- E2 (Estradiol)
- Estrogen hormone measured via blood test during stimulation to track follicle growth and guide medication dosing.
- Ectopic Pregnancy
- A pregnancy that implants outside the uterus, most commonly in a fallopian tube. Requires prompt medical treatment.
- Embryo Transfer (ET)
- The procedure that places one or more embryos into the uterus via a thin catheter. Usually painless and does not require anesthesia.
- Endometriosis
- A condition where tissue similar to the uterine lining grows outside the uterus. Can affect fertility and is common among IVF patients.
- ERA Test
- Endometrial Receptivity Analysis, a biopsy-based test to determine the optimal window for embryo transfer in patients with repeated implantation failure.
- FET
- Frozen Embryo Transfer, a cycle in which previously frozen and thawed embryos are transferred to the uterus.
- FSH
- Follicle Stimulating Hormone. Used as a blood test marker for ovarian reserve, and also the main ingredient in injectable stimulation medications.
- Gardner Grading
- Blastocyst quality scoring system combining expansion (1-6), inner cell mass (A-C), and trophectoderm (A-C). Example: 4AA is high quality.
- Gestational Carrier
- A person who carries a pregnancy using embryos created by another couple or individual. Distinct from a traditional surrogate.
- GnRH Agonist
- Medication (such as Lupron/leuprolide) used to suppress the body's natural hormone cycle before or during IVF stimulation.
- GnRH Antagonist
- Medication (such as Ganirelix or Cetrotide) used during stimulation to prevent the body from releasing eggs prematurely.
- hCG Trigger
- An injection of human chorionic gonadotropin given approximately 36 hours before egg retrieval to trigger final egg maturation.
- ICSI
- Intracytoplasmic Sperm Injection, a fertilization technique where a single sperm is injected directly into an egg. Used for male factor infertility or low fertilization history.
- Implantation
- The process by which an embryo attaches to the uterine lining. Successful implantation is required for pregnancy to continue.
- IUI
- Intrauterine Insemination, a less invasive fertility treatment where washed sperm are placed directly into the uterus around ovulation.
- LH
- Luteinizing Hormone. Naturally triggers ovulation. In IVF, a premature LH surge is suppressed with antagonist or agonist medications.
- Luteal Phase
- The phase after ovulation or retrieval when progesterone supports the uterine lining. In IVF, progesterone supplementation is typically required.
- Mosaic Embryo
- An embryo containing a mix of chromosomally normal and abnormal cells, as detected by PGT-A. Transfer decisions are made case by case with your clinic.
- OHSS
- Ovarian Hyperstimulation Syndrome, a potential complication of stimulation where the ovaries become swollen and fluid can leak into the abdomen. Ranges from mild to severe.
- PGT-A
- Preimplantation Genetic Testing for Aneuploidy, screens embryos for chromosomal abnormalities before transfer to improve success rates and reduce miscarriage risk.
- PGT-M
- Preimplantation Genetic Testing for Monogenic disorders, screens embryos for specific inherited single-gene conditions.
- Progesterone
- Hormone critical for preparing and maintaining the uterine lining after ovulation or retrieval. Administered as injections, suppositories, or vaginal gel in IVF cycles.
- Retrieval
- Egg retrieval procedure, typically transvaginal under light sedation. Follicles are aspirated with a needle to collect mature eggs.
- RPL
- Recurrent Pregnancy Loss, defined as two or more consecutive pregnancy losses. Often prompts investigation into chromosomal, anatomical, or immune factors.
- Stim
- The stimulation phase of an IVF cycle during which injectable gonadotropin medications are used to grow multiple follicles.
- Thin Lining
- A uterine lining (endometrium) that measures less than approximately 7mm, which may reduce implantation rates. Treatment options include estrogen, Viagra, or other protocols.
- Transfer
- Short for embryo transfer, the procedure that places embryo(s) into the uterus.
- Trigger Shot
- Final injection (hCG or Lupron) administered approximately 36 hours before egg retrieval to complete egg maturation.
- TWW
- Two Week Wait, the approximately 10-14 day period between embryo transfer and the first pregnancy blood test. Often the most emotionally intense phase.
- Uterine Factor
- Structural or anatomical conditions of the uterus (such as fibroids, polyps, or septum) that may affect implantation or pregnancy.
- Vitrification
- Ultra-rapid flash-freezing technique used to cryopreserve eggs and embryos. Survival rates with vitrification are significantly higher than older slow-freeze methods.
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