Glossary of Terms

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A benign disease that involves the abnormal growth of endometrial tissue (the lining of the uterus) into the uterine wall or myometrium. Can be associated with abnormal bleeding or periods and some data suggest lower pregnancy rates in women with adenomyosis. There is no medical or surgical remedy for adenomyosis.


Scarring is a result of tissue injury. The damage can be caused by infections such as Gonorrhea and Chlamydia, or by previous operations such as removal of cysts or an appendectomy. Endometriosis also causes adhesion formation. Adhesions involving the tubes and/or the ovaries can cause infertility by preventing the normal pick-up of the egg from the surface of the ovary. If adhesions are mild, they can be treated by laparoscopic surgery. If the disease is severe however, surgery will not restore normal fertility. Adhesions inside the uterine cavity are also known as Asherman’s syndrome and may result from prior surgeries of the uterine lining such as polyp or fibroid removal or dilation and curettage procedures. These adhesions can be diagnosed by saline ultrasonography or hysteroscopy and can be removed by hysteroscopy.

Alpha Fetal Protein

A protein secreted by fetal tissue that can be present in the mother's bloodstream. If present in high levels, it can be associated with congenital fetal anomalies such as neural tube defects.


An embryo is said to be aneuploidy if it contains an abnormal number of chromosomes. Down Syndrome, or Trisomy 21 is one form of aneuploidy, one of the few chromosome number abnormalities compatible with live birth. Most chromosome aneuploidies result in implantation failure or early miscarriage.

Anti-Mullerian Hormone (AMH)

AMH is a blood test that directly measures ovarian reserve. It is produced directly by early stage ovarian follicles.  High levels (over 1.0) are favorable, while low levels (less than 1.0) indicate decreased ovarian reserve. AMH may be the best measure of the menopausal transition and ovarian age. It may also be useful in predicting ovarian hyperstimulation syndrome, the effects of chemotherapy, and in determining the treatment of PCOS.

AMH seems a superior predictor of ovarian response compared to other markers, including age, and day 3 FSH and estradiol. It offers similar predictive value compared to AFC. AMH can be drawn at any time in the menstrual cycle, and is not affected by hormonal therapy, including oral contraceptives.

Antisperm Antibodies

Antibodies directed against sperm. If directed against the head of the sperm, they can interfere with normal fertilization. 

Antral Follicle Count

An assessment of the number of small follicles present in the ovary at any point in the cycle. This count is ideally between 10-20 follicles and if much lower, can suggest diminished ovarian reserve. See also: Follicle, Diminished Ovarian Reserve.

Arcuate Uterus

A mild deformity of the uterus that involves the presence of a very small separation in the midline of the fundus (the upper part of the uterus) inside the uterine cavity. This condition is usually not associated with infertility or recurrent miscarriages, and therefore rarely needs any form of therapy.

Asherman’s Syndrome

Adhesions inside the uterine cavity are also know as Asherman’s syndrome and may result from prior surgeries of the uterine lining such as polyp or fibroid removal or dilation and curettage procedures. These adhesions can be diagnosed by saline ultrasonography or hysteroscopy and can be removed by hysteroscopy. 

Assisted Hatching

The process of helping an embryo to hatch by making a surgical slit using a specialized laser in the zona pellucida (see Zona pellucida) or "shell." Assisted hatching is performed on Day 3 embryos and frozen-thawed embryos routinely. 

Assisted Reproductive Technologies (ART)

ART is a term for the collective high- technology Infertility treatment procedures such as In Vitro Fertilization, Intracytoplasmic Sperm Injection, Frozen Embryo Transfer, and Testicular Sperm retrieval, that require laboratory handling of sperm and /or eggs.


The complete absence of sperm. It can result from obstruction of the vas deferens (the duct that carries the sperm from the testicles to the urethra) or from failure of the testes to produce sperm. MESA and TESE are two ART procedures to obtain sperm from azoospermic males.


Basal Body Temperature

Abbreviated BBT. Indirect evidence of ovulation can be obtained with the basal body temperature chart. The temperature can be taken orally with a digital thermometer immediately upon awakening and before any activity. This is recorded on a special graph that enables you to visualize the different temperature shifts. The temperature will drop to its lowest point, 1-2 days prior to ovulation, and then rises and remains elevated until a couple of days before impending menstruation. If the individual is pregnant the temperature will remain elevated. This elevation is not considered a fever because it will never exceed 38ºC (100ºF). This test is unfortunately not very reliable in every woman, and is therefore not used universally. Urine ovulation prediction testing is a better way to document ovulation and to determine prospectively when ovulation will occur. 

Bicornuate Uterus

A congenital abnormality of the uterus that involves a partial lack of fusion of the two parts of the uterus to varying degrees. A single cervix is present. In the majority of cases it does not cause infertility, but recurrent miscarriages have been reported in rare instances, similarly to premature births. If treatment is needed, it is through abdominal surgical repair. 


An embryo that has undergone multiple cellular divisions with the formation of a cavity within it. A fertilized egg reaches the blastocyst stage usually 4 to 5 days after fertilization. Most embryo transfers at Pacific Fertility Center are done with blastocyst stage embryos. 


Cervical Mucus

Cervical mucus is secreted by glandular cells that are present in the cervix. This mucus protects the uterus from invasion by bacteria present in the vagina. It also plays an important role in infertility. The cervical mucus, in response to the estrogen hormone, becomes thin and elastic at the time of ovulation. This allows the sperm to travel through the cervix and the uterus to reach the egg in the fallopian tube. It also helps the sperm to stay alive in the cervix for a longer period of time.  A thick and dense mucus could prevent the passage of sperm through the cervix.

Cervical Stenosis

Narrowing of the cervical canal in such a way that menstrual flow can partially or completely be impeded. It is often the result of cervical injury due to surgery such as cone biopsy done for an abnormal Pap smear. It can cause infertility by hampering the normal passage of sperm through the cervix, and can often be treated by intrauterine insemination that bypasses the cervix altogether.


The part of the uterus that opens into the vagina. It is the segment that is checked for abnormal cells by a Pap smear. It is connected to the uterine cavity by a hollow canal called the cervical canal. The cervix secrets mucinous secretions (see Cervical Mucus) which play a major role in the transport of sperm in its journey towards the egg.


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

Chemical Pregnancy

A pregnancy in its earliest stages that was detected by blood hormone levels but a gestational sac never developed.


A bacteria responsible for a sexually transmitted infection that can affect the tubes by causing permanent damage and thus infertility. Often occurs without significant symptoms. 


The nuclear structure of every living cell. Every human cell has normally 46 chromosomes. These chromosomes are made up of genes that govern all of the body's functions, and are also responsible for all the physical characteristics of an individual. Human gametes (i.e. eggs and sperm) contain only 23 chromosomes. When unified during fertilization, the total number of 46 chromosomes is thus restored. Abnormalities of chromosomes can result in miscarriages or congenital abnormalities. Age affects the quality of chromosomes in an egg and that is why infertility and miscarriages are more common in older women. For instance, the incidence of Down's Syndrome increases when a woman gets older. 

Clinical Pregnancy

A pregnancy that has advanced to a stage where a gestational sac and/or a fetus can be seen by ultrasound.

Clomiphene Citrate

Also known by the trade names of "Clomid" and "Serophene," it is a synthetic estrogen hormone that is commonly used for ovulation induction. It comes in 50 mg tablets that are taken by mouth once a day for 5 days in the early part of the menstrual cycle. Due to its anti estrogenic actions, some of its side effects include thickening of the cervical mucus and thinning of the endometrial lining. The former can interfere with normal passage of sperm through the cervix to reach the egg, and the latter with implantation.  Some women may complain of hot flashes (10%), nausea and/or breast discomfort (2-5%). Visual symptoms (blurring) rarely occur (<1.5%) but are an indication to discontinue therapy. 

Corpus Luteum

A follicle that releases an egg at the time of ovulation is subsequently called the corpus luteum. This is initially a partially collapsed cystic space that later can become a true cyst, and is very active in hormone secretion. Its major product is progesterone. If pregnancy does not occur, the corpus luteum "dies" roughly 10 to 14 days after ovulation. This leads to a sudden drop in progesterone levels, which in turn leads to menstruation. If, on the other hand, pregnancy occurs, the newly developing placenta secretes the HCG hormone, which salvages the corpus luteum and stimulates it to continue making progesterone. This placental support of the corpus luteum is indispensable for the first 7 weeks of pregnancy. From that point on, the placenta starts making its own progesterone and the corpus luteum is no longer needed. Therefore, it shrinks and becomes the "corpus albicans.”


The process of freezing sperm, eggs or embryos in extremely low temperatures (-196°C). This technique has been used for decades to freeze sperm. It allows us to quarantine the sperm while the donor is tested for transmittable infectious diseases. The sperm can then be thawed when necessary and used in artificial insemination. More recently, we have been able to freeze and preserve human embryos. This has enabled us to freeze and save embryos resulting from in vitro fertilization. These embryos can also be later thawed and transferred back to the uterus. This allows us to transfer fewer embryos at any one transfer, reducing the risks of high-order multiple births.

Cumulus Granulosa

A group of cells that surround the human egg. They are responsible for the nourishment of that egg. These cells secrete the hormone estrogen that causes the uterine lining to grow.

Cystic Fibrosis (CF)

The most common inherited single-gene mutation genetic disease in humans. Children with CF inherit a mutated copy of the gene CFTR from each parent. These children have serious lung and digestive problems that can lead to a shorter lifespan. 


D and C

Dilation and curettage. It is the process of gradually dilating the cervix to the point of being able to introduce an instrument (curette) to scrape the surface of the uterine cavity (endometrium). A suction cannula is also often used if the amount of tissue removed is great. This procedure is often used to treat abnormal bleeding, incomplete miscarriages and abnormal uterine pathology such as polyps or small fibroids. It is done under sedation and sometimes under general anesthesia. Potential complications include infection and uterine perforation.


Diminished or Decreased Ovarian Reserve (DOR)

This is an infertility diagnosis for women that have elevated basal FSH levels, low AMH levels or low antral follicle counts and/or poor responses to fertility medications. Women with this diagnosis have a reduced potential for successful pregnancy with any particular cycle’s treatment but the overall odds of conception is better related to a woman’s age. Women with very severe DOR often will need egg donation to successfully conceive, especially if they are 39 and older. 

Down Syndrome

Also known as Trisomy 21. An individual that has 3 copies of chromosome 21. Physical features include mild mental retardation, heart and thyroid defects. This is the major anomaly being tested for when pregnant women undergo Chorionic Villus Sampling (CVS) or amniocentesis in early pregnancy. The incidence of Down Syndrome and other aneuploidies is increased with increasing maternal age.



See Estradiol

Ectopic Pregnancy

A normal pregnancy results when the embryo implants inside the uterus. When implantation occurs outside the uterus, an ectopic pregnancy ensues. Such an abnormal pregnancy can be located in the tubes, the ovaries, the cervix or inside the abdomen. The most common symptoms are abnormal bleeding and lower abdominal pain. Women who have tubal damage (such a scarring from infection) are at an increased risk for an ectopic pregnancy. About one out of four conceptions after an ectopic pregnancy is a repeat ectopic pregnancy. About 2-3% of all in vitro fertilization pregnancies turn out to be ectopic. 


Lay term for oocyte. The largest cell in the human body. Unites with the sperm to make a zygote and eventually a baby. Carries 23 chromosomes. 

Egg Donation

This process involves the stimulation of a woman's hormones with fertility drugs, the retrieval of her eggs, the subsequent fertilization with the sperm of the recipient's partner, and the transfer of the resultant embryos to the uterus of the recipient. Women who might or will need egg donation generally fall into the following categories:

  1. Women with no ovaries, either because of their congenital absence or their surgical removal
  2. Women with early (premature) menopause
  3. Older women
  4. Women who fail to produce adequate number of eggs after stimulation with fertility drugs
  5. Women with serious transmittable genetic traits or diseases
  6. Women who have decreased ovarian reserve

Egg donors should be young women (ideally between 21 and 29 years of age). Most egg donations are done anonymously, however known donors are also acceptable in many instances. 

Egg Retrieval

The process of introducing a long needle through the vagina and into the ovaries to aspirate the follicles that contain the eggs. It is done under ultrasound guidance. The ovaries are visualized on the ultrasound screen and the needle aspirates the follicles with gentle suction. The aspirated fluid is sent to the embryologist who examines it and isolates the egg. The procedure is done under sedation and is therefore painless. It takes about 20 minutes to complete and the patient is discharged one hour later. The patient is not allowed to drive because of slight drowsiness for a few hours after the procedure. Complications are very rare and include bleeding and infection.