IVF Terminology

IVF terminology signs

In vitro fertilization is sometimes a foreign language.  Aneuploid embryos, Gonadotrophin-Releasing antagonists, oocytes, and intracytoplasmic sperm injects can hardly be considered everyday words!  While there is no need to become fluent in the language of in vitro fertilization, here is a quick guide to some of the more common terminology you may encounter.


Amniocentesis is a 2nd-trimester pregnancy procedure used to detect various fetal abnormalities. It involves sampling a small amount of amniotic fluid surrounding the fetus using a needle under ultrasound guidance.

Aneuploid embryo

An embryo with more or fewer than the usual 46 chromosomes often leads to a miscarriage or failure to establish a pregnancy.

Antral Follicle Count (AFC)

The number of follicles observed through ultrasound at the beginning of the menstrual cycle, typically on day 2 or 3, indicates the ovarian reserve.

Anti-Müllerian Hormone (AMH)

A hormone frequently measured in a woman during her fertility evaluation to assess her ovarian reserve. It is secreted by the small ovarian follicles that grow during the menstrual cycle.


An embryo with more or fewer than the usual 46 chromosomes often leads to a miscarriage or failure to establish a pregnancy.

Assisted Hatching (AH)

A technique used to help the embryo break out of its outer shell (zona pellucida) and thereby improve the chances of successful implantation in the uterus.  Before the embryo is transferred to the uterus, the embryologist creates a small opening in the embryo’s zona pellucida by applying acid or laser. The embryo can more easily extrude itself from the shell and implant in the uterus lining.  

Assisted Reproductive Technology (ART)

Treatments that include the handling of eggs, sperm, and embryos.


Around 5-6 days after fertilization, an embryo reaches the blastocyst stage. During this stage, the embryo has developed a fluid-filled cavity, and the cells have started to differentiate, forming the early placenta and the embryo itself. The embryo consists of about 100 cells at this point, and it is ready for implantation into the uterus lining to continue its development.

Cervical Cancer Screening

A screening test to determine the presence of cervical cancers. It is done by touching a swab to the cervix to collect cells for examination by a pathologist.

Chemical Pregnancy

A positive pregnancy test but the embryo never fully implants in the uterus. These pregnancies typically spontaneously decline without further development.  Chemical pregnancies are relatively common and usually occur due to chromosomal abnormalities or other factors that prevent the embryo’s proper development.

Clinical Pregnancy

A special gland that forms from the ruptured follicle in the ovary.  It produces progesterone during the second half of the menstrual cycle, which is necessary to prepare the uterine lining for implantation.  If the egg is fertilized and implantation occurs, the corpus luteum continues to produce progesterone to support the early stages of pregnancy until around 8-10 weeks of gestation, when the placenta takes over hormone production.  If pregnancy does not occur, the corpus luteum regresses, leading to a decrease in progesterone levels, and the menstrual cycle restarts.

Diminished Ovarian Reserve

This refers to a condition where there is a reduced quantity or quality of eggs in a woman’s ovaries, indicating a decline in her reproductive potential.  This depletion in the number of eggs can result in reduced fertility and may affect a woman’s ability to conceive.

Ectopic Pregnancy

An ectopic pregnancy is when a fertilized egg implants and grows outside the uterus, most commonly in the fallopian tube. This type of pregnancy is not viable and can pose serious medical risks to the mother if left untreated. Diagnosis of an ectopic pregnancy is often made by tracking Human Chorionic Gonadotropin (hCG) levels and observing the absence of a gestational sac in the uterus during an ultrasound examination.


The female sex cell produced in the ovary and once fertilized by a sperm is referred to as an embryo.

Egg Retrieval

A surgical procedure in which eggs are removed from the ovaries with a thin needle and ultrasound. This procedure is done under light anesthesia, so the patients are asleep during the entire process.  An egg retrieval typically lasts 20-30 minutes.


A fertilized egg has begun cell division but is not yet a fetus.

Embryo Culture

A liquid medium is necessary for growing embryos outside of the human body.

Embryo Transfer

The placement of the growing embryo into the uterus.

Endometrial Biopsy

The extraction of a small piece of tissue from the lining of the uterus for microscopic inspection.

Estradiol (E2)

A form of estrogen that is produced by the follicular cells of the ovary.  Estradiol is measured via a blood draw to gauge the strength and development of the follicles during a treatment cycle.


A hormone that causes the uterus lining to thicken during the first half of the menstrual cycle in preparation for the implantation of an embryo.

Euploid Embryo

An embryo with an average number of 46 chromosomes.


A fluid-filled pocket in the ovary usually contains a single egg and the surrounding cells that produce hormones. Follicles start extremely small and grow more prominent under the influence of hormones.

Follicle-Stimulating Hormone (FSH)

Secreted by the Pituitary Gland and responsible for stimulating the growth of follicles. FSH is measured in the blood at specific times during the menstrual cycle to help measure ovarian reserve.


An organism’s reproductive cells. Female gametes are called ova or egg cells, and male gametes are called sperm. Gametes carry only one copy of each chromosome.

GnRH agonist 

Triggers the Pituitary Gland to release LH and FSH.  It also stimulates follicle growth and prevents premature ovulation.

GnRH antagonist (GnRH)

A GnRH antagonist blocks the release of LH and FSH from the pituitary gland, thereby preventing premature ovulation.  It is used in assisted reproductive treatments to help control the timing of follicle growth and egg retrieval.

Human Chorionic Gonadotropin (hCG)

A hormone that is used to detect a pregnancy and is produced by the cells surrounding the developing embryo.  In IVF, Human Chorionic Gonadotropin induces ovulation and is often called “triggering ovulation.” The timing of when to take the hCG shot is essential in the IVF cycle.

Hysterosalpingogram (HSG)

An x-ray procedure to examine whether the fallopian tubes are open and to view the uterine cavity.  Special X-ray dye is injected through the uterus, and then X-ray pictures are taken to show where the dye travels.


A small telescopic camera is placed through the cervical canal into the uterine cavity.  This allows direct visualization of the uterus lining.  This also permits the removal of any polyps or fibroids in the uterine cavity.

Intracytoplasmic sperm injection (ICSI)

A procedure in which a single sperm is injected directly into an egg to attempt fertilization.


A surgical procedure during which a long, narrow fiber-optic instrument (laparoscope) is inserted through an incision in or below the woman’s navel, providing a view of her reproductive organs and abdominal cavity.

Luteinizing Hormone (LH)

A pituitary-produced hormone that usually causes ovulation and maturation of the egg.  But in males, it stimulates testosterone production and is essential in producing sperm cells.


Loss of a pregnancy before the 20th week of gestation.


The percentage of all moving sperm in a semen sample. Typically, 50% or more sperm in a sample moves rapidly.


The medical term for an egg.

Ovarian hyperstimulation syndrome (OHSS)

A condition in which the ovaries become swollen because of ovarian stimulation.

Ovarian reserve

The number of follicles a woman has indicates her reproductive potential. 

Ovarian Cyst

Fluid-filled follicles that have not been fully reabsorbed by the body from previous menstrual cycles. These are common in natural and stimulated cycles and naturally go away independently without treatment.  If, after a few cycles, the cyst persists or grows, the IVF doctor may reschedule a procedure to drain or remove the cyst.


A uterine polyp is a growth attached to the inner wall of the uterus that extends into the uterine cavity.  Polyps are often removed by hysteroscopic surgery because, if left untreated, they can grow (due to pregnancy hormones) and occupy space in the uterine cavity that the developing fetus needs. Sometimes, a polyp is seen in an ultrasound but is reabsorbed by the body before a second ultrasound.

Preimplantation Genetic Diagnosis (PGD)

A screening test that determines whether specific genetic or chromosomal disorders exist in embryos. A biopsy of the embryo is performed three days after the egg retrieval. These cells are then permitted to grow and undergo chromosomal and genetic testing.

Preimplantation Genetic Screening (PGS)

This test is used to screen embryos for chromosome abnormalities.


A hormone secreted in the second half of the menstrual cycle prepares the uterus lining for the implantation of a fertilized egg.

Selective Reduction

A medical procedure to decrease the number of fetuses in a multiple pregnancy.


The male reproductive cells fertilize a woman’s egg.

Spina Bifida

A congenital disability of the spinal column.  Spina bifida is the failure of the spine to close properly during development.  Taking folic acid can prevent spina bifida.

Transvaginal Ultrasound Aspiration

An ultrasound-guided technique for egg retrieval in which a needle is passed through the vagina into the ovarian follicle and suction is used to retrieve the egg.


A fertilized egg before cell division begins.

As you embark on your IVF journey, armed with a better understanding of assisted reproduction terminology, we hope this knowledge empowers you and clarifies your path.   We wish you all the success in the world as you pursue your dreams of building a family.


Author: Karen Synesiou, Infertility Portal, Inc.