Chorionic villus sampling (CVS) is a prenatal test that is used to detect birth defects, genetic diseases, and other problems. During the test, a small sample of cells (called chorionic villi) is taken from the placenta
where it attaches to the wall of the uterus.
Chorionic villi are tiny parts of the placenta that are formed from the fertilized egg, so they have the same genes as the baby.
If you have certain risk factors for having a baby with a birth defect or genetic disease, you may be offered CVS to detect the problem early in pregnancy.
What diseases or disorders can CVS identify?
CVS can help identify chromosomal problems such as Down syndrome or other genetic diseases such as cystic fibrosis, Tay-Sachs disease and sickle cell anemia. CVS is considered to be 98% accurate in the diagnosis of chromosomal defects, such as Down syndrome.
Since the procedure also identifies the sex of the fetus, it can also help identify disorders that are linked to one sex (such as certain types of muscular dystrophy which occur most often in males).
CVS does not detect open neural tube defects such as spina bifida. If you have CVS, you may want to also consider having a blood AFP test later in pregnancy to screen for those problems.
What are the benefits of CVS?
CVS can be done early in pregnancy (earlier than amniocentesis), and results are usually obtained within 10 days. Getting this kind of information early allows a woman to make choices in the beginning stage of her pregnancy. If a woman chooses to terminate the pregnancy after receiving abnormal test results, the pregnancy termination will be safer than if she waits for amniocentesis results.
What are the risks of CVS?
CVS may carry a slightly higher risk of miscarriage than amniocentesis, since the procedure is done in early pregnancy. Infection may also occur. Rare cases of defects in baby's fingers or toes have been reported, especially when CVS was done before 9 weeks. This risk seems unrelated to the experience of the doctor performing the test or how the test was done. Due to this potential risk, 10 weeks is generally the earliest recommended time to perform this test.
A miscarriage is any pregnancy that ends spontaneously before the fetus can survive. Miscarriage usually occurs before the 13th week of pregnancy. The cause of a miscarriage cannot always be determined. The most common causes of a miscarriage in the first trimester are collagen vascular disease (lupus), hormonal problems, diabetes, chromosomal abnormalities, and congenital abnormalities of the uterus.
Down syndrome is a chromosomal disorder that results in the presence of an additional third chromosome 21, also referred to as trisomy 21. Most individuals with Down syndrome have widely recognizable physical characteristics. The severity of Down syndrome ranges from mild to severe. Diagnostic testing for Down syndrome include amniocentesis, chorionic villus sampling, and percutaneous umbilical cord sampling. The most common risk factor for Down syndrome is a woman's age.
Cystic fibrosis is a disease of the mucus and sweat glands. Cystic fibrosis is an inherited disease. The outcome of the disease leaves the body malnourished, bulky and fouls smelling stools, vitamin insufficiency, gas, painful or swollen abdomen, infertility, susceptible to heat emergencies, and respiratory failure. There is no cure for cystic fibrosis, treatment of symptoms is used to manage the disease.
Sickle cell anemia (sickle cell disease), a blood disease which shortens life expectancy, is cause by an inherited abnormal hemoglobin. Symptoms may include bacterial infections, painful swelling of the hands and feet, fever, leg ulcers, fatigue, anemia, eye damage, and lung and heart injury. Treatment for sickle cell anemia aims to manage and prevent the worst manifestations of the disease and focuses on therapies that block red blood cells from stacking together, which can lead to tissue and organ damage and pain.
Fragile X syndrome is the most common inherited form of mental retardation. It's caused by a mutation on the X chromosome. People with Fragile X syndrome suffer from physical, social, emotional, speech, language, sensory, intelligence, and learning impairments. There is no definitive treatment for Fragile X, though there are ways to minimize the symptoms.
Genetic disease is a disorder or condition caused by abnormalities in a person's genome. Types of genetic inheritance include single inheritance (for example, cystic fibrosis, sickle cell anemia, Marfan syndrome, and hemochromatosis), multifactoral inheritance, chromosome abnormalities (for example, Turner syndrome, and Klinefelter syndrome), and mitochondrial inheritance (for example, epilepsy and dementia).
Birth defects have many causes and currently, are the leading cause of death for infants in the first year of life. Some of the causes of birth defects include genetic or chromosome problems. Exposure of the mother to rubella or German measles during pregnancy, or using drugs or alcohol during pregnancy. The treatment for birth defects depends upon the condition of the effected child.
A common form of short stature, achondroplasia (dwarfism) is a genetic condition causing a disorder of bone growth. Complications of achondroplasia that need monitoring include (this is not all inclusive) stenosis and compression of the spinal cord, a large opening under the skull, lordosis, kyphosis, spinal stenosis, hydrocephalus, middle ear infections, obesity, and dental crowning. Achondroplasia is caused by mutations of the FGFR3 gene.
Hemophilia is one of a group of inherited bleeding disorders. Hemophilia A and B are inherited in an X-linked recessive genetic pattern and is more common in males. Symptoms of hemophilia include bleeding into the joints, muscles, GI or urinary tract, or brain or skull. Treatments for hemophilia is generally replacement of blood clotting factors.
There are many syndromes and defects that may cause urine blockage in newborns. Defects in the urinary tract that may cause urine blockage include vesicoureteral reflux, ureteropelvic junction obstruction, bladder outlet obstruction, posterior urethral valves, nerve disease, and ureterocele. Syndromes that may cause urinary blockage include congenital heart defects, esophageal atresia, and prune belly syndrome. Treatment for urine blockage in newborns depends on the cause of the blockage.
While the patient's history and physical examination are the building blocks
of making a medical diagnosis, the ability to peer inside the body can be a
powerful tool. Ultrasound is an imaging technique that provides that
ability to medical practitioners.
What is an ultrasound?
Ultrasound produces sound waves that are beamed into the body causing return
echoes that are recorded to "visualize" structures beneath the skin. The ability
to measure different echoes reflected from a variety of tissues allows a shadow
picture to be constructed. The technology is especially accurate at seeing the
interface between solid and fluid filled spaces. These are actually the same
principles that allow SONAR on boats to see the bottom of the ocean.
What is ultrasonography?
Ultrasonography is body imaging using ultrasound in medical diagnosis. A
skilled ultrasound technician is able to...
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