amniotic fluid

https://doi.org/10.1351/goldbook.09635
Fluid that surrounds the foetus in the amniotic sac.
Note: A specimen is obtained by a technique called amniocentesis, in which a long needle is inserted into the amniotic sac through the abdominal wall, through which fluid is withdrawn.
Source:
PAC, 2018, 90, 1121. (Terminology of bioanalytical methods (IUPAC Recommendations 2018)) on page 1123 [Terms] [Paper]