Glossary of Terms

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A fertilized egg that has begun the cycle of cell division.

Embryo Transfer

The process of depositing fertilized eggs (or embryos) inside the uterus. This often occurs 3 to 5 days following egg retrieval. A predetermined number of embryos are first placed inside a special catheter, which is then introduced inside the uterus through the cervix. The embryos are then gently injected and the catheter removed. This procedure is done in a position similar to a pelvic examination for a Pap smear. The patient will remain in that position for roughly fifteen minutes before being discharged. The number of embryos to be transferred depends upon on the age of the woman and the quality of the embryos. The patient will make the informed decision regarding the number of embryos to be transferred after conferring with her physician.

Endometrial Biopsy

A procedure that involves taking a small sample of tissue from the inside lining of the uterus (called the endometrium). An endometrial biopsy is done for many reasons. In a case of investigation for infertility, it is performed to evaluate the endometrium for its readiness to accept the embryo. An abnormal test is said to be "out-of-phase" in relation to the date of the cycle. An endometrial biopsy is also performed for abnormal uterine bleeding to diagnose hormonal imbalances or an anatomic cause for the bleeding, such as polyps, hyperplasia (abnormal benign growth of the endometrium) or cancer.


The presence and growth of tissue resembling the endometrium outside the uterus. Typical locations include over the tubes, the ovaries, the uterus, the peritoneal lining of the pelvis, the bowel and other unusual areas. The disease is benign but usually progressive. In advanced stages it causes severe scarring of the ovaries and/or tubes which can result in infertility. Even milder forms of the disease whereby only few spots of endometriosis are present are associated with infertility. The cause of endometriosis is not known with certainty, but several mechanisms are involved. More recently, immunological causes have been implicated in the mechanism of infertility in patients with endometriosis. The classic symptoms of endometriosis are cyclic pelvic pain and infertility. Medical or surgical therapy is successful only for the relief of pain. Studies have shown that medical therapy does not improve infertility. Surgery for endometriosis is similarly not successful to treat infertility except in instances where there are mild adhesions partially blocking the tubes.


The inside lining of the uterus where implantation of the embryo occurs.


A surgical procedure to view the pelvic organs (laparoscopy) or the uterine cavity (hysteroscopy) via a small, fiber-optic telescope. Therapeutic surgery may also be performed during these procedures.


Sperm travels from the testicles through a tubular structure called the epididymis into the vas deferens and through the urethra and penis. Sperm undergoes advanced maturation during its stay in the epididymis.

Estradiol Valerate

An estrogen preparation for human supplementation to prepare the uterine lining for implantation.

Estrogen (or Estradiol)

The major female hormone secreted by the ovaries. A normally menstruating woman ovulates once a month about 14 days after the start of the menstrual cycle. The egg secretes estrogen as it grows. The level of this hormone peaks at the time of ovulation, it then drops and peaks again about a week after ovulation. Estrogen is responsible for the normal growth and differentiation of both the follicle and the egg. It also plays an important role in preparing the endometrial lining where implantation would occur in case of pregnancy. Estrogen also changes the quality and texture of the cervical mucus, making it thinner and more elastic. This allows the normal passage of sperm through the cervix towards the uterus and the tube where it meets the egg. The hormone estrogen is important in helping to maintain healthy vaginal tissue. It also has beneficial effects on bone and the cardiovascular system. For these reasons, estrogen replacement is recommended to most menopausal women.  When estrogen is measured on the second or third day of the cycle, its level reflects the health of the eggs. Ideally, a level less than 80 ug/ml is desirable prior to the initiation of ovulation induction or IVF.


Fallopian Tubes

A hollow muscular tubular organ that is connected to the uterus at one end, and opens inside the abdomen close to the ovaries at the other. The latter part is made of finger-like projections, also called “fimbria," that pick up the ovulated egg from the surface of the ovary. The egg meets the sperm at the mid-junction of the tube where fertilization occurs. The fertilized egg then travels to the uterine cavity where implantation takes place. There are normally two fallopian tubes, one on each side of the uterus. Damage to these tubes is common with sexually transmitted diseases, such as Gonorrhea and Chlamydia. They can also be easily damaged during pelvic or abdominal surgeries or in patients with severe endometriosis. Reconstructive tubal surgery for infertility can be done in some women. The success rate depends on the state of the tubes prior to the surgery. If for instance, the tubes are blocked and swollen, the success rate is extremely small in achieving pregnancy. In such cases, IVF should be the treatment of choice. Recent data has also shown that swollen tubes lower IVF success rates; therefore, it is strongly recommended that swollen damaged tubes (hydrosalpinx) be surgically removed prior to IVF.

Fertility Preservation

Refers to undergoing IVF for the purposes of freezing eggs or embryos. Candidates for fertility preservation are women facing chemotherapy treatment that may harm their eggs or women who delay childbearing due to career commitments or other personal circumstances. This significant step forward in fertility treatment enables women to take advantage of their body’s fertility at a time when eggs are at their healthiest. 


The unification of sperm and egg to form a zygote (the earliest stage of human life). The zygote would then become an embryo, and then a fetus. A sperm or an egg contains half of the genetic make-up of its species. A normal human cell contains 46 chromosomes, while an egg or sperm contains only 23 chromosomes. After successful and normal fertilization, the number of chromosomes becomes 46 (23 from the egg and 23 from the sperm).


A fertilized egg is called a zygote. Further cellular division and differentiation yields an embryo. Once organic differentiation occurs, i.e., the embryo acquires human-like features, it is called a fetus.

Fibroid Tumors (or Myomas)

Benign tumors of the muscle of the uterus. Fibroids develop in one of every four women at some point during their lifetime. If present inside the uterine cavity, they can interfere with implantation. Fibroids can also cause problems if they become large in size and impinge or put pressure on the uterine lining. They are treated by surgical removal, either via laparoscopy, hysteroscopy, or a major abdominal surgery.


The delicate finger-like projections at the end of the fallopian tubes that are responsible for picking up the egg from the surface of the ovary and transporting it to the inside of the tube.


A fluid-filled space (like a balloon) present inside the ovary that contains and nourishes the egg. In a normal cycle, a woman will usually ovulate only one egg. Very early in the cycle, however (and actually before the cycle even begins), many small minute follicles containing immature eggs are recruited. During the first 5 to 7 days after the start of a period only one of these follicles will mature and grow. This leading follicle will increase and be ready for ovulation roughly 2 weeks after the start of the menstrual cycle. The follicle will then burst with ovulation and release the egg that is picked up by the finger-like projections (fimbria) of the fallopian tube. The collapsed follicle will become the corpus luteum.

Follicle Stimulating Hormone

Abbreviated as FSH. A hormone secreted by the pituitary gland; FSH stimulates the growth and development of ovarian follicles. It is the main hormone present in the gonadatropin medications Gonal-F, Follistim and Bravelle, and comprises half of the hormones in Menopur. A blood test for this hormone on the third day of the menstrual cycle is crucial in evaluating how the ovaries are functioning. A significantly elevated level (>10) implies possible decreased ovarian reserve.

Women with higher basal FSH levels may not respond as well to fertility medications in terms of the numbers of follicles and eggs recruited but does not necessarily predict who will and who will not get pregnant. Age is a better predictor of successful pregnancy. The level of FSH also assists us in determining the ideal dosage and regimen of fertility agents necessary to initiate proper ovarian stimulation in a subsequent cycle of treatment.


This fertility medication contains recombinant FSH. In other words, the medication is made up of cells that have been genetically engineered through recombinant DNA technology to produce large quantities of human FSH. It is self-administered by subcutaneous injection.

Frozen Embryo Transfer

The process of thawing and placing into the uterus embryos previously frozen from a preceding IVF cycle. Currently most embryos are frozen at the blastocyst stage (Day 5 embryos) and over 90% of embryos frozen by vitrification will survive the freeze-thaw process. See also “vitrification.”


See Follicle Stimulating Hormone.



The female egg and the male sperm.


A GnRH Antagonist (see definition below) used in IVF cycles to prevent ovulation prior to egg retrieval. 

Gestational Carrier

A woman who accepts to bear (or be pregnant with) the child of another woman who is incapable of becoming pregnant using her own uterus. Women who need surrogates (an older term for what we now refer to as a "gestational carrier") include those who do not have a uterus, have an abnormal uterine cavity, have had several recurrent miscarriages or have had recurrent failed IVF cycles. Women that may have medical problems that would make a pregnancy risky for the mother or baby would also be a candidate to work with a gestational carrier.

Gestational Surrogacy

Also see Surrogate & Classic Surrogacy. In gestational surrogacy, the gestational carrier does not contribute any genetic materials since the egg and the sperm come from prospective parents or a separate donor. 


Gonadotropin releasing hormone is the single most important hormone controlling ovarian function. It is secreted by the hypothalamus and controls LH and FSH secretion by the pituitary gland, which in turn directly controls ovarian function. Absent or abnormal secretion of GnRH results in irregular cycles and lack of ovulation. GnRH is secreted in an episodic manner by the hypothalamus to be able to carry out its functions.

GnRH Antagonist

A synthetic hormone similar to GnRH agonists but without any initial “flare” effect on the pituitary as seen with GnRH agonists. Antagonists (Ganirelix or Cetrotide) are usually administered in IVF cycles during the last 3-4 days of stimulation to prevent an LH surge from occurring, thereby preventing the release of the eggs from the ovaries prior to egg retrieval. 


A synthetic hormone similar to GnRH that is administered in a continuous fashion by daily subcutaneous injections (Lupron) or nasal spray (Synarel). This hormone will actually suppress pituitary and ovarian function. Given this fact, we are able to use the medication to suppress the hypothalamic-pituitary-ovarian axis in many women undergoing ovulation induction for IVF. The benefit of this suppression is that it allows us to control the ovaries ourselves without interference from the hypothalamus or the pituitary.


Follicle Stimulating Hormone (FSH) and Lutenizing Hormone (LH) are pituitary hormones that stimulate egg production, ovulation, and estrogen and progesterone production. The gonadatropin FSH is the hormone that is the main ingredient in Gonal-f, Follistim, Pergonal, Repronex and Humegon. Injections of gonadatropin medications will cause the ovaries to make multiple eggs.


This fertility medication is a gonadatropin hormone containing very pure human FSH. It is produced by cells that have been genetically engineered through recombinant DNA technology to produce large quantities of human FSH. It is self-administered by subcutaneous injection.


A sexually transmitted disease that can cause tubal disease and infertility. If caught early, it is completely curable and will not negatively influence your fertility potential. Common symptoms include pelvic pain, vaginal discharge and fever.



Human Chorionic Gonadotropin is the major hormone secreted by the placenta. In the early stages of pregnancy, continued survival of the corpus luteum (the follicle that releases the egg) is totally dependent on HCG and, in turn, the survival of the pregnancy is dependent upon hormones secreted by the corpus luteum during the 7th week of pregnancy. Thereafter, the corpus luteum is gradually replaced by placental hormone secretions. Studies have shown that after administering HCG intramuscularly, ovulation occurs 38 to 40 hours afterwards. This is why during an IVF cycle, egg retrieval is scheduled 30 to 40 hours after the HCG shot. Similarly, during simple ovulation induction with Clomiphene or Gonadatropins, HCG is sometimes given to trigger ovulation. HCG is chemically very similar to LH or luteinizing hormone, which signals the ovulation process to begin. Insemination or intercourse is then planned according to the time that HCG was administered.

Hemi-zona Assay

A test that helps determine if sperm are able to attach and penetrate the covering of an egg or zona pellucida.

Human Chorionic Gonadotropin

See HCG.


A condition where there is elevated blood levels of the hormone Prolactin. This hormone is secreted by the pituitary gland. There are several diseases that can result in abnormally high Prolactin levels. Most commonly, this is due to a small and benign Prolactin secreting tumor in the pituitary gland called Prolactinoma. Often this can result from an abnormally slow functioning thyroid gland. The treatment is specific to the cause, but medical management with Bromocriptine (Parlodel) is the first line of therapy.


A small portion in the base of the brain that plays a major role in regulating the hormones involved in fertility and the menstrual cycle. (See GnRH).