What is the difference between chorionic villi sampling and amniocentesis?

Answer 1

Amniocentesis is a procedure performed on pregnant women to determine possible risk factors with their developing fetus. A long needle is inserted through the abdomen into the uterus, being guided by an ultrasound, that extracts amniotic fluid. This amniotic fluid is then further tested to determine certain risks such as Down syndrome. Although amniocentesis does have it benefits of obtaining this kind of knowledge, it also poses threats to the fetus such as a .8% chance of miscarriage, clubfeet, trauma to the mother, preterm labor and an infection of the uterus. According to an article published in a Canadian journal, a study in Canada showed that amniocentesis performed between weeks 11 and 13, resulted in 29 out of 4,374 women gave birth to children with clubfeet. Because of this risk, doctors generally try to avoid performing amniocentesis before week 15 of pregnan What is Amniocentesis? 1. Invasive medical procedure performed during pregnancy to determine abnormalities or fetal development 2. Also called an amnio 3. More than 99% accurate B. An amnio is optional, but in certain circumstances it is advised by a doctor I. How? A. Generally anesthetic isn't used B. Lie on back on exam table C. Hollow needle inserted into the uterus, through the abdomen D. Needle extracts amniotic fluid E. Guided by ultrasound F. Entire procedure usually takes an hour II. Why? A. To detect genetic disorders i. Down's Syndrome ii. Trisomy 13 iii. Trisomy 18 iv. Sexual chromosome abnormalities-Turner Syndrome v. Cystic fibrosis vi. Sickle cell disease vii. Neural tube defects-spina bifida B. Cannot detect: i. Cleft lip/palate ii. Heart malformations C. Determine if lungs are mature enough for preterm delivery III. When A. Generally between weeks 16-20 B. Risks before week 15 i. Clubfeet ii. Preterm labor C. Only after week 20 if necessary i. Early labor IV. Who? A. If blood work suggests defects B. If ultrasound suggests defects C. Family history of genetic defects D. If parent is a carrier of genetic disorders E. Specific need to know sex for certain diseases V. Risks A. Miscarriage i. One in 300 B. Uterine infection C. Stress D. Vaginal bleeding/cramping E. Needle injury i. Rare ii. Fetus may move arm/leg in path of needle VI. Prepration A. No major prep required B. Eat and drink as normal C. Need full bladder D. Sign conset form E. Have someone accompany you to drive you home VII. Results A. Results take a few days to two weeks B. If results are positive for defects: i. Choose to continue pregnancy ii. Where to have baby iii. Whether or not to have a C-section? VIII. Alternatives A. Chorinoic Villus Sampling (CVS) B. Karyotpying

CVS is a similar procedure done to detect the same abnormalities as an amnio but the method is different. As opposed to extracting the amniotic fluid from the abdomen with a needle, it is extracted vaginally from a small tube that will then test the fluid for abnormalities/defects.