T4 -- See Thyroxine.

TeBG -- See Testosterone-estradiol-binding Globulin.

Termination -- The ending of a pregnancy by choice by induced labor (resulting in a live birth or stillbirth) or abortion. See Abortion.

Teratogen -- Any substance capable of causing malformations in a developing embryo.

TESA -- See Testicular Sperm Aspiration.

TESE -- See Testicular Sperm Extraction.

Testes -- The two male sexual glands contained in the scrotum. They produce the male hormone testosterone and the male reproductive cells (sperm).

Testicle -- The male gonad. It produces sperm and male sex hormones.

Testicular Biopsy -- A minor surgical procedure used to take a small sample of testicular tissue for microscopic examination; a test used to diagnose male fertility problems when no other means is available (this is because the biopsy procedure itself may cause testicular damage).

Testicular Enzyme Defect -- A congenital enzyme defect that prevents the testes from responding to hormonal stimulation. Will result in oligospermia or azozoospermia.

Testicular Failure -- Primary: A congenital, developmental, or genetic error resulting in a testicular malformation that prevents sperm production. Secondary: Acquired testicular damage, for example, from drugs, prolonged exposure to toxic substances, or a varicocoele.

Testicular Feminization -- An enzymatic defect that prevents a man from responding to the male hormone testosterone. The man will look like a woman, but karyotyping will reveal a normal XY male chromosome pattern, and testosterone levels will be in the normal male range.

Testicular Sperm Aspiration (TESA) -- A needle biopsy of the testicle used to obtain small amounts of sperm. A small incision is made in the scrotal skin and a spring loaded needle is fired through the testicle. Usually does not result in enough sperm to freeze for later use.

Testicular Sperm Extraction (TESE) -- An open biopsy where a small piece of testicular tissue is removed through a skin incision. The tissue is placed in culture media and separated into tiny pieces. Sperm are released from within the seminiferous tubules where they are produced and are then extracted from the surrounding testicular tissue. This procedure can be done using local anesthetic of IV sedation. It is possible to get enough sperm to freeze for future use.

Testicular Stress Pattern -- A semen analysis result showing depressed sperm production, poor sperm motility, and poor sperm morphology. The pattern is consistent with secondary testicular failure or illness.

Testicular Torsion -- When testicle twists on itself, cutting off its own blood supply. Causes extreme pain, and requires immediate surgical repair to reduce damage to the testicle

Testosterone -- The male hormone responsible for the formation of secondary sex characteristics and for supporting the sex drive. Testosterone is also necessary for spermatogenesis.

TET -- See Tubal Embryo Transfer.

Therapeutic Abortion -- A termination of a pregnancy sue to sever abnormalities in the fetus or where the mother's health is at risk. See Abortion.

Threatened Miscarriage -- An incident in which certain symptoms such as vaginal bleeding or severe cramping, occur during the first half of pregnancy. The symptoms may stop or may progress to a miscarriage.

Thyroid Gland -- The endocrine gland in the front of the neck that produces thyroid hormones to regulate the body's metabolism.

Thyroid Releasing Hormone (TRH) -- A peptide hormone synthesized in the hypothalamus and passed through the hypophyseal portal venous system. In the anterior pituitary, TRH stimulates synthesis and release of Thyrotropin (TSH).

Thyroid Stimulating Hormone (TSH) -- Also called thyrotropin. A hormone produced by the pituitary gland (at the base of the brain) that promotes the growth of the thyroid gland (in the neck) and stimulates it.

Thyroxine (T4) -- A chemical substance made by the thyroid gland The thyroid gland uses iodine to make thyroid hormones. Thyroxine (T4), one of the most important thyroid hormones, has four iodine molecules attached to its molecular structure. Thyroid hormones are essential for the function of every cell in the body. They help regulate growth and the rate of chemical reactions (metabolism) in the body.

Tipped Uterus -- When the uterus is tipped toward a woman's back instead of tilting forward as is more common. This alone should not be considered a cause of infertility.

TNF --- See Tumor Necrosis Factor

Tocolytic -- A drug used to relax uterine contractions and to try to stop premature labor.

TORCH Organisms -- Toxoplasmosis, syphillis, rubella, cytomegalovirus, herpes simplex, and other diseases which may harm the embryo/fetus.

Torsion -- The twisting of the testis inside the scrotum. Besides causing extreme pain and swelling, the rotation twists off the blood supply and causes severe damage to the testicle. Torsion of the ovary may also occur in a woman suffering from hyperstimulation, a complication of ovulation induction treatment.

Total Effective Sperm Count -- An estimate of the number of sperm in an ejaculate capable of fertilizing an egg. Total sperm count X percent motility X percent of forward progressive motility X percent normal morphology.

Toxin -- A poison produced by a living organism (plant or animal), such as by some bacteria.

Transuterine Fallopian Transfer (TUFT) -- The placement of an embryo inside the fallopian tube after in vitro fertilization. The transfer is made by threading a tube through the cervical canal and uterus and depositing the embryo into the fallopian tube. The process is meant to mimic the natural process of a fertilized embryo traveling down the tube and implanting in the uterus.

Transvaginal --- Through the vagina or across its wall as in a surgical procedure

Transvaginal Ultrasound -- An ultrasound examination performed by means of inserting a probe into the vagina. This type of ultrasound is common for viewing follicle growth This can produce better images in early pregnancy that could be obtained with conventional abdominal sonograms.

TRH -- See Thyroid-releasing Hormone.

Triphasic -- Having three phases. Used to describe a basal body temperature chart that shows three levels of temperatures: low temperatures before ovulation, a shift up of at least .4 degrees Fahrenheit after ovulation, and then another shift upward that may coincide with the implantation of an embryo.

Trophoblastic Disease -- See Molar Pregnancy.

TSH -- See Thyroid Stimulating Hormone.

Tubal Embryo Transfer (TET) -- The placement of an embryo inside the fallopian tube after in vitro fertilization. The process is meant to mimic the natural process of a fertilized embryo traveling down the tube and implanting in the uterus.

Tubal Ligation -- Surgical sterilization of a woman by obstructing or tying the fallopian tubes.

Tubal Patency -- Open and unobstructed fallopian tubes.

Tubal Pregnancy -- See Ectopic Pregnancy.

Tubocornual Anastomosis -- Surgery performed to remove a blocked portion of the fallopian tube and to reconnect the tube to the uterus. Tubouterine implantation may also be performed to remove fallopian tube blockage near the uterus and reimplant the tube in the uterus.

Tuboplasty -- Plastic or reconstructive surgery on the fallopian tubes in order to correct abnormalities which may lead to blockage or otherwise cause infertility.

Tubotubal Anastomosis -- Surgery performed to remove a diseased portion of the fallopian tube and reconnect the two ends; sterilization reversal.

Tumor -- An abnormal growth of tissue that can be benign or malignant (cancerous).

Tumor Necrosis Factor (TNF) --- a monokine produced in various parts of the body. It is important in stimulating leukocytosis, fever and necrosis (death of some tissues surrounded by healthy tissue). This might be described as the body's natural form of chemotherapy.

TUFT -- See Transuterine Fallopian Transfer.

Turner's Syndrome -- The most common genetic defect contributing to female fertility problems. The ovaries fail to form and appear as slender threads of atrophic ovarian tissue, referred to as streak ovaries. Karyotyping will reveal that this woman has only one female (X) chromosome instead of two or a mosaic (46XX and 45X).