chorionic biopsya technique that enables the prenatal assessment of a foetus between the 7th and 11th week of pregnancy, involving the sampling of cells from the chorionic villus. These villi are small, fingerlike outgrowths of the CHORION (2) that, at the time of the sampling, are full of rapidly dividing foetal cells. A biopsy of the villus is taken with a small tube inserted through the vagina and cervix. No anaesthetic is needed and no amniotic fluid is collected. The large number of dividing foetal cells in the sample means that chromosomal and biochemical studies can be quickly completed, so that termination (if required) is usually before the 10th week, a significantly less traumatic period of gestation than termination after AMNIOCENTESIS.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005