Glossary | The Children's Hospital of Philadelphia

Center for Fetal Diagnosis and Treatment

Glossary of Maternal and Fetal Medicine Terms

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A condition that occurs when there is too much acid in body fluids.

Alimental Formula

A nutritious formula that is easier for babies to digest.

Alpha-fetoprotein (AFP)

A protein produced by the fetus that is excreted into the amniotic fluid and passes into the maternal blood. Abnormal levels of alpha-fetoprotein in amniotic fluid or maternal blood may indicate an increased risk for a variety of birth defects or chromosomal disorders. It may also be due to a miscalculated due date or to multiple fetuses.


A condition that is present at birth and affects the formation of the brain and the skull bones that surround the head, resulting in only minimal development of the brain. There is no bony covering over the back of the head and there may also be missing bones around the front and sides of the head. Anencephaly is incompatible with life.


A test performed to determine chromosomal and genetic disorders and certain birth defects. An amniocentesis can also be used to determine fetal lung maturity. The test involves inserting a needle through the abdominal and uterine walls into the amniotic sac to retrieve a small sample of amniotic fluid.


A procedure in which fluid is infused into the uterus through a needle inserted through the abdomen and uterine wall to restore normal levels of amniotic fluid.


A procedure, similar to an amniocentesis, in which a large amount of amniotic fluid is removed.

Amniotic Fluid

Clear yellow-colored fluid that surrounds the fetus in the uterus. It protects the fetus from injury and helps to regulate the temperature of the fetus. Early in pregnancy, amniotic fluid is produced by the mother's placenta. Later, the fetus' kidneys produce it.

Amniotic Sac

A thin-walled sac containing amniotic fluid that surrounds the fetus during pregnancy.


Absence of amniotic fluid.

Anoxic Brain Injury

An injury that occurs when the brain is starved of oxygen.

Aqueductal Stenosis

Blockage of cerebral spinal fluid (CSF) flow through the aqueduct of Sylvius. This aqueduct is a narrow canal in the center of the brain through which CSF moves between the third and fourth ventricle (chambers in the brain that produce and store CSF).


Congenital absence or closure of a normal body opening (anus) or tubular structure (esophagus or intestines).


Birth Defect

A structural anomaly of an organ or organ system that occurs during fetal development.

Bowel Dilatation

A stretching or expansion of the bowel.

Bronchopulmonary Sequestration (BPS)

A fetal lung mass made up of non-functioning lung tissue. It receives its blood supply from the aorta.


The examination of the bronchi (the main airways of the lungs) using a flexible tube (bronchoscope). Bronchoscopy helps to evaluate and diagnose lung problems, assess blockages, obtain samples of tissue and/or fluid, and/or to help remove a foreign body.



A surgical procedure involving insertion of a flexible catheter into one of the large blood vessels.

Cerebral Spinal Fluid

Clear fluid that flows over the brain and spinal cord to cushion and protect it.

Cervical Teratoma (also known as giant neck mass)

A large tumor in the neck that can compress the fetus' airway.

Cesarean Section

Delivery of a baby through an incision in the mother's uterus.

Chiari malformation

A problem present at birth that affects the area in the back of the head where the brain and the spinal cord connect.

Chorionic Villus Sampling (CVS)

A procedure involving the removal of a small amount of placental tissue. Cells from this tissue can be tested for certain genetic abnormalities and chromosomal disorders.

Chromosomal Deletion

Absence of a piece of a chromosome.


Structures in our cells that carry genes, which are the basic units of heredity. Humans have 23 pairs of chromosomes, one member of each pair inherited from the mother, the other from the father. Each chromosome can contain hundreds or thousands of individual genes.

Color Flow Doppler Ultrasound

An ultrasound that uses color to show the speed of blood flow through blood vessels.


Present at birth.

Congenital Abnormality(also known as congenital anomaly)

An abnormality present at birth

Congenital Anomaly (also known as congenital abnormality)

An abnormality present at birth

Congenital Cystic Adenomatoid Malformation (CCAM)

A fetal lung mass caused by an overgrowth of lung tissues. CCAMs may be cystic, fluid-filled masses or solid masses.

Congenital Diaphragmatic Hernia (CDH)

A hole in the diaphragm in which abdominal organs can push up into the chest limiting normal lung growth.

Congenital Heart Defect (also see congenital heart disease)

A structural or functional heart problem.

Congenital Heart Disease (also see congenital heart defect)

A structural or functional heart problem.

Congenital High Airway Obstruction Syndrome (CHAOS)

A complete or nearly complete blockage of the fetal airway.


An ultrasound-guided procedure similar to an amniocentesis in which a small amount of fetal blood is drawn from the umbilical cord during pregnancy (see fetal blood sampling)



The loss of genetic material, relating to either chromosomes or a gene.


Primary muscle used for breathing, separating the chest from the abdomen.


Extracorporeal Membrane Oxygenation

A special technique using a heart-lung machine to take over the work of the lungs and sometimes the heart. It is used to support or replace an infant's premature or sick lungs by providing oxygen and removing carbon dioxide waste products so the lungs can rest.


The fetus is first called an embryo between the second and eighth weeks of prenatal development.


A tube connecting the mouth and the stomach, used in swallowing.

Ex Utero Intrapartum Therapy (EXIT)

An EXIT procedure is a surgical procedure used to deliver babies who have airway compression. An opening is made in the anesthesticized mother's uterus, similar to a C-section, and the baby is partially delivered through the incision. The surgeon then establishes an airway so the fetus can breathe independently.


Fetal Blood Sampling

Withdrawing a small sample of blood from the fetus by inserting a long, thin needle through the mother's uterus into a fetal blood vessel. Used for diagnosis and sometimes treatment (blood transfusion). (see cordocentesis)

Fetal Bowel Herniation

A condition in which the fetal bowel protrudes through a defect in the abdominal wall into the umbilical cord.

Fetal Echocardiogram

A specialized ultrasound that examines fetal heart structure and function.

Fetal Fibronectin (FFN)

A protein that helps "glue together" the amniotic sac and the lining of the uterus. Testing for the presence of fetal fibronectin may help if a woman is at risk for preterm delivery.

Fetal Heart Rate Monitoring

Evaluation of the rate and rhythm of the fetal heartbeat.

Fetal Hydrops

A life-threatening condition in which fluid accumulates in fetal tissues.

Fetal Liver Herniation

A condition in which the fetal bowel protrudes through a defect in the abdominal wall into the umbilical cord.

Fetal Lobectomy

Surgical resection (removal) of a portion of the fetal lung to remove a lung mass.

Fetal Skin Biopsy

A ultrasound-guided test in which a fine needle is passed through the mother's uterus to collect a small sample of fetal skin.

Fetal Muscle Biopsy

A diagnostic test in which a fine needle is passed through the mother's uterus to collect a small sample of muscle cells. This test is done to diagnose a variety of muscle disorders.

Fetal Surveillance Testing

A group of tests used to monitor fetal well-being. These tests include biophysical profile, Doppler ultrasound, NST and/or measurement of amniotic fluid volume.

Fetoscopic Bipolar Cord Coagulation

An procedure in which a fetoscope (a thin tube with a light and camera lens at one end) is inserted through the mother's abdomen into the uterus. Electrical current (cautery) is used to cut off the blood supply from umbilical arteries and vein to a non-viable, parasitic twin.

Fetoscopic Laser Coagulation

A surgical procedure in which a fetoscope (a thin tube with a light and camera lens on one end) is inserted through the mother's abdominal wall into the uterus. A laser (light) beam is used to seal (photocoagulate) the blood vessels on the surface of the placenta. This procedure is used to treat twin-twin transfusion syndrome.

Fetoscopic Radio Frequency Ablation

A procedure in which radio waves are used to seal (coagulate) the blood supply from umbilical arteries and veins to a non-viable, parasitic twin.


A procedure involving the passage of a thin endoscope through the mother's abdomen and into the uterus to directly observe the fetus and placenta.


An unborn baby from the eighth week after fertilization until delivery.



A defect in the abdominal wall in which the fetal bowel protrudes through the opening and floats freely in the amniotic fluid.


Determined by genes.

Genetic Counseling

Providing an assessment of heritable risk factors and information to patients and their relatives concerning the consequences of a condition, the probability of developing or transmitting it, and ways in which it can be prevented, treated and managed.

Genetic Studies

Diagnostic tests that evaluate for conditions that have a tendency to run in families.

Genetic Testing

Tests performed to determine if a person or fetus has a gene or chromosome change.


The length of a pregnancy; the number of weeks from conception until birth.

Giant Neck Mass (GNM)

A large tumor in the neck that can compress the fetus' airway

Giant Omphalocele

A condition in which most of the fetal liver and bowel protrude through an abdominal wall defect into the end of the umbilical cord. It occurs in 1 in 10,000 births.



An opening in the abdominal muscle through which a portion of intestine or other internal organ may protrude.

High-frequency Ventilation

A specialized ventilator that delivers hundreds of tiny puffs of air each minute to keep a baby's airways open and to protect the baby's lung tissue.

Hydramnios (see polyhydramnios)

Too much amniotic fluid.


A build up of cerebral spinal fluid (CSF) which may cause the pressure inside of the head to increase and the skull bones to expand to a larger-than-normal appearance. This may be due to a lack of absorption, blockage of flow, or overproduction of the cerebral spinal fluid (CSF) that is found inside of the ventricles (fluid-filled areas) inside of the brain.

Hydrops Fetalis (see fetal hydrops)

A life-threatening condition in which fluid accumulates in fetal tissues.


Decreased oxygen supply to the body's tissues.


Imaging Studies

Methods used to produce a picture of body structures. Two imaging methods used to detect fetal anomalies are magnetic resonance imaging (MRI) and ultrasound.

In-utero Microcystourethroscopy

A procedure in which a small, flexible tube with a light and a camera lens at the end (endoscope) is used tin inspect the fetal bladder.

In-utero Stem Cell Transplantation

A fetal treatment that involves injecting stem cells into the fetal abdomen.

Intestinal Atresia

A congenital defect in which part of the intestine is completely blocked or absent.

IV feeds

Fluids provided to babies through a tube inserted into a vein or artery.


Keyhole Bladder

A keyhole-like appearance seen on ultrasound that is characteristic of lower urinary tract obstruction.



A procedure in which a small, flexible tube with a light and a camera lens (endoscope) is used to inspect the larynx (voice box).


An abnormal change in the body's tissues or organs.

Level II Ultrasound

A detailed, anatomic ultrasound that assesses all fetal organ systems.

Liquid Ventilation

A treatment for the lungs of premature babies in which a special liquid is put into the lungs as a way of delivering oxygen. This treatment also helps the baby's lungs to expand and develop.

Lower Urinary Tract Obstruction (LUTO)

A developmental abnormality in which the lower portion of the urinary tract becomes obstructed or blocked.


A vascular condition made up of enlarged lymphatic vessels.


Magnetic Resonance Imaging (MRI)

A diagnostic procedure that uses a combination of large magnets, radiofrequencies and a computer to produce detailed images of organs and structures within the body.

Maternal Mirror Syndrome

A rare maternal illness in which the mother develops symptoms that mirror those of her sick fetus. It occurs as a consequence of an edematous fetus or placenta.

Miscarriage (also called spontaneous abortion)

Early pregnancy loss.


Twin pregnancy with a shared placenta.

Multiple Fetal Bladder Taps

Serial collections of fetal urine for evaluation.

Myelodysplasia (Also called spina bifida)

A condition, present at birth, that refers to abnormal development of the back bones, spinal cord, surrounding nerves and the fluid-filled sac that surrounds the spinal cord. This neurological condition can cause a portion of the spinal cord and the surrounding structures to develop outside the body. This can occur anywhere along the spine.


Naso-Gastric Tube (NG tube)

A soft, flexible plastic tube that is inserted through a nostril, passed through the throat and esophagus, and into the stomach. Used to administer feedings or medications. May also be used to empty the stomach of air or stomach contents.

Neonatal Intensive Care Unit (NICU)

A special care nursery that uses advanced technology and trained health professionals to care for sick and premature newborns.

Nitric Oxide

An inhaled gas, similar to oxygen, that is given to increase blood flow in the baby's lungs. This increases oxygen to the lungs.

Non-stress Test (NST)

A noninvasive test that monitors fetal heart rate as an indicator of fetal well-being.


Obstructive Uropathy

An obstruction in the urinary tract that prevents normal urine drainage. Read More »


Too little amniotic fluid.


A congenital anomaly in the abdominal wall in which the abdominal organs herniate (protrude) through the abdominal wall into the base of the umbilical cord.

Open Fetal Surgery

Performing surgery on a fetus still inside the mother's womb. The mother is anesthetized and an incision is made through the abdominal wall and into the uterus. The fetal surgeon then repairs the defect in the fetus, replaces the amniotic fluid and closes the incisions. The mother has a short hospital stay to monitor her healing and to ensure that premature labor will not occur.


A hormone secreted by the pituitary gland to stimulate milk production and contractions of the smooth uterine muscles. Synthetic oxytocin can be used to start or increase uterine contractions.



An organ, shaped like a flat cake, that only grows in the uterus during pregnancy and provides a metabolic interchange between the fetus and mother. (The fetus takes in oxygen, food and other substances and eliminates carbon dioxide and other wastes.)

Polyhydramnios (see hydramnios)

Too much amniotic fluid.

Posterior Urethral Valves

An abnormality of the urethra in which the urethral valves (small leaflets of tissue) have a narrow, slit-like opening that partially or completely blocks urine outflow. Backup of the urine can cause damage to all of the urinary tract.

Predictive Genetic Testing

Determines the chances that a healthy individual with or without a family history of a certain disease might develop that disease.


A disorder that occurs only during pregnancy and the postpartum period. It affects both the mother and the unborn baby. It is a progressive condition characterized by high blood pressure and the presence of protein in the urine. Women may also experience swelling, rapid weight gain, headaches and/or changes in vision.

Prenatal Diagnosis

Used to diagnose a genetic disease or condition in the developing fetus.

Presymptomatic Genetic Testing

Used to determine whether persons who have a family history of a disease but no current symptoms have the gene alteration associated with the disease.


Before 37 weeks of pregnancy.

Primary Repair

A surgical repair performed immediately after birth.

Pulmonary Hypoplasia

Underdevelopment of lung tissue.


Renal Electrolyte Profile

A group of tests that evaluates urine to provide information about kidney function.

Renal Dysplasia

Abnormal development of the kidneys.

Respiratory Distress Syndrome

Also called RDS or hyaline membrane disease, respiratory distress syndrome is a condition of premature infant lungs due to insufficient surfactant (see surfactant).

Reversed Arterial Perfusion

When blood flows in reverse through an acardiac twin (one without a functioning heart) as it is pumped by the other, typically normal twin.


Sacrococcygeal Teratoma (SCT)

A tumor, usually benign, that grows from the base of the fetus' tailbone (coccyx).


A small, flexible tube that provides drainage of fluid from the fetus into the amniotic sac.

Silastic Sheeting ("silo")

A flexible synthetic covering used as a temporary closure for open abdominal wounds.

Spina Bifida (Also called myelodysplasia)

A condition, present at birth, that refers to abnormal development of the back bones, spinal cord, surrounding nerves and the fluid-filled sac that surrounds the spinal cord. This neurological condition can cause a portion of the spinal cord and the surrounding structures to develop outside the body. This can occur anywhere along the spine.


A collection of traits, health problems and/or birth defects in an individual that usually has a single underlying cause.

Staged Repair

A series of surgeries performed over time to correct a single condition.

Stuck Twin (see twin-twin transfusion syndrome)

The donor twin.


A natural coating in the lungs made up of proteins and fats. It reduces the surface tension of air sacs in the lung and makes it easier to breathe. Synthetic surfactant is used to help immature lungs rest and heal.



Removal of fluid from the thorax (chest).

Thoracoamniotic Shunting

Placing a shunt (small, flexible tube) into the fetal thorax (chest) to provide continuous drainage of fluid in the chest.


The tube connecting the mouth and the lungs. Used in breathing.


A temporary artificial airway created by surgically inserting a breathing tube into the windpipe.


To transfer organs, tissues or cells from one person to another or from one area of the body to another, in order to replace a diseased structure and to restore function.


A pregnancy is divided into three trimesters, each about three months.


An abnormal lump or mass of tissue. Tumors can be benign (not cancerous) or malignant (cancerous).

Twin Reversed Arterial Perfusion Syndrome (TRAP)

A rare complication of identical twinning in which one twin lacks a functioning cardiac system and is dependent upon the twin with the fully functioning cardiac system (the "pump" twin). This places a large demand on the heart of the "pump" twin and may lead to heart failure.

Twin-Twin Transfusion Syndrome (TTTS)

A rare and serious complication in identical twins who share a placenta that has connections between the two twin's blood vessels. TTTS usually occurs when there is an uneven flow of blood between the twins across these connections. TTTS gets progressively worse as the pregnancy continues. One twin is smaller with little amniotic fluid around it and is called the "donor" twin. The other twin is larger and has too much amniotic fluid around it and is called the "recipient" twin. Over time, the recipient twin can develop a form of heart failure while the donor twin stops growing.


Uteroplacental Blood Flow

Flow of blood across the placenta from the mother to the fetus and from the fetus to the mother.

Uteroplacental Gas Exchange

Exchange of respiratory gases (oxygen and carbon dioxide) across the placenta from the mother to the fetus and from the fetus to the mother.

Ultrafast Fetal MRI

Magnetic resonance imaging with faster scanning times and higher resolution images for diagnosing fetal abnormalities.

Ultrasound (Also called sonography)

A diagnostic imaging technique which uses high-frequency sound waves and a computer to create images of blood vessels, tissues and organs. Ultrasounds are used to view internal organs as they function, and to assess blood flow through various vessels. In pregnancy, the sound waves create an image of the fetus' body and organs, as well as surrounding tissues.

Umbilical Cord

A rope-like cord connecting the fetus to the placenta. The umbilical cord contains two arteries and a vein, which carry oxygen and nutrients to the fetus and carry waste products away from the fetus.

Umbilical Cord Blood Transplant

A bone marrow transplant using stem cells from umbilical cord blood.


Belly button.


Two narrow tubes that carry urine from the kidneys to the bladder.

Uterine Irritability

Weak but frequent pre-term labor contractions.

Uterine Wall

The wall of the uterus.

Uterus (also called the womb)

The uterus is a hollow, pear-shaped organ located in a woman's lower abdomen, between the bladder and the rectum, that sheds its lining each month during menstruation and in which a fertilized egg (ovum) becomes implanted and the fetus develops.


Ventral Wall Defect

Congenital abnormality in the abdominal wall that allows abdominal organs to protrude through the abdominal wall.

Vesicoamniotic Shunting

Placing a shunt (a small, flexible tube) into the fetal bladder to provide continuous drainage when a obstruction is present.


Removal of fluid from the bladder.



A diagnostic test that uses invisible electromagnetic energy beams to produce images of tissues, bones and organs onto film.

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