What does amniocentesis mean?
Amniocentesis is a noun referring to a prenatal medical procedure in which a thin needle is inserted through the mother's abdominal wall into the uterus to withdraw a small sample of the amniotic fluid surrounding the fetus. That fluid contains fetal cells and chemicals that can be analyzed to detect chromosomal conditions such as Down syndrome, certain genetic disorders, and neural tube defects. The procedure is generally performed between the fifteenth and twentieth weeks of pregnancy, often when earlier screening tests suggest an elevated risk or when there is a family history of a specific condition. Because it is an invasive test carrying a small risk of miscarriage, amniocentesis is usually offered only when its potential benefits outweigh those risks, and the decision to undergo it is frequently an emotionally weighty one for expectant parents. The word derives from Greek roots meaning 'puncture of the amnion,' and it appears chiefly in medical literature, healthcare guidance, and news coverage of reproductive medicine.
nounA medical procedure in which a small sample of the amniotic fluid surrounding a fetus is withdrawn through a needle inserted into the uterus, typically to test for genetic or chromosomal abnormalities.
- A prenatal diagnostic procedure in which a needle is used to withdraw a sample of amniotic fluid for laboratory testing, most commonly to detect chromosomal abnormalities such as Down syndrome.
"The obstetrician recommended amniocentesis after the ultrasound revealed a possible chromosomal abnormality."
"At sixteen weeks, she underwent amniocentesis to determine whether the fetus had any chromosomal abnormalities."
"The amniocentesis results came back clear, easing the couple's anxiety about the family history of cystic fibrosis."
The plural follows the standard -is → -es pattern for Latinized Greek nouns. It appears mainly in medical statistics and research contexts discussing multiple procedures.
"The clinic reported performing several hundred amniocenteses over the past year."
Its name literally means 'puncturing the amnion' — the word was coined from Greek roots describing exactly what the needle does.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of amniocentesis
Amniocentesis combines two Greek-derived elements: 'amnio-' comes from the Greek 'amnion,' the membrane enclosing the fetus, and '-centesis' derives from the Greek 'kentēsis,' meaning a puncture or piercing. The compound follows a pattern shared by other modern medical terms such as paracentesis and thoracentesis, all built on the same puncturing root. The procedure itself was developed in the mid-twentieth century, becoming established in clinical practice during the 1950s and 1960s as techniques for fetal diagnosis advanced.
Related word forms
How amniocentesis is actually used
Amniocentesis is a formal medical term used primarily in clinical, journalistic, and patient-education contexts rather than everyday conversation. It carries a neutral-to-serious connotation, as it is typically discussed in connection with prenatal screening decisions and carries a small risk of miscarriage that clinicians usually mention alongside it.
Easily confused with amniocentesis
Chorionic villus sampling tests placental tissue earlier in pregnancy (around 10–13 weeks), whereas amniocentesis samples amniotic fluid and is usually performed later (around 15–20 weeks).
Amniotomy is the deliberate rupturing of the amniotic membranes to induce labor, while amniocentesis is a diagnostic withdrawal of a small fluid sample.