|
|
Amniocentesis |
| Definition: |
| Amniocentesis is a diagnostic procedure performed by inserting a hollow needle through the abdominal wall into the uterus and withdrawing a small amount of fluid from the sac surrounding the fetus. |
| Alternative Names: |
| Culture - amniotic fluid; Culture - amniotic cells |
| How the test is performed: |
| The exact location of the fetus is determined, usually by ultrasound (see pregnancy ultrasound). The skin of the abdomen is scrubbed and a topical anesthetic may be applied, or a local anesthetic may be injected into the skin. A long, thin needle is inserted through the abdomen and into the uterus. A small amount of fluid is taken from the fluid-filled sac surrounding the fetus (usually about 1 cc. per week of gestation). |
| How to prepare for the test: |
| This test does not require an overnight stay in the hospital. You must sign a consent form. Your bladder must be full for the ultrasound. There are no food or fluid restrictions. |
| How the test will feel: |
| If an anesthetic is used, there may be a sharp, stinging sensation for a few seconds. When the needle enters into the amniotic sac, a sharp pain lasting a few seconds may be felt. Some women have the sensation of pressure in the lower abdomen when the fluid is withdrawn. After the procedure, there may be some minor cramping. |
| Why the test is performed: |
|
The test can detect chromosomal disorders -- such as Down's syndrome, structural defects -- such as spina bifida (open spine, where the vertebrae fail to close), anencephaly (a condition in which the brain is incomplete or missing), and many rare, inherited metabolic disorders. Late in the pregnancy, lung maturity can be determined using this test. |
| Normal Values: |
| The analysis shows no defects in the chromosomes and no excess of alpha fetoprotein (a protein produced by the fetus) or bilirubin. |
| What abnormal results mean: |
| Amniocentesis can be used to diagnose a large number of genetic and chromosomal abnormalities in the fetus. In addition, it is helpful in the diagnosis of the severity of Rh incompatibility, lung maturity, and neural tube defects (such as spina bifida). DNA testing is available for many diseases. New diseases are being added to this list as genetic research advances. Ask your obstetrician or geneticist if you have a question about a specific disease. |
| What the risks are: |
| There is a slight chance of infection or injury to the fetus. There is even a smaller chance of miscarriage. This test is typically performed when a problem is suspected, so the benefits outweigh the risk. |
| Special considerations: |
| There may be alternatives to the amniocentesis. These should be discussed with the health care provider. |
Reviewed By: Dominic Marchiano, M.D., Department of Obstetrics & Gynecology, University of Pennsylvania Medical Center, Philadelphia, PA. Review provided by VeriMed Healthcare Network.
 |
A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is the first of its kind, requiring compliance with 53 standards of quality and accountability, verified by independent audit. A.D.A.M. is among the first to achieve this important distinction for online health information and services. A.D.A.M. is also a founding member of Hi-Ethics (www.hiethics.com) and subscribes to the principles of the Health on the Net Foundation (www.hon.ch). |
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 2003 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
