Which mechanism is used for a fine needle aspiration?

Fine needle aspiration (FNA) uses a thin needle to aspirate cells, which are then packed into the lumen of the needle for cytological evaluation. It is distinct from core biopsy, which uses cutting needles to obtain tissue cores.

According to AIUM Practice Parameters:

“Fine needle aspiration involves insertion of a thin needle into a lesion to aspirate cells for cytologic analysis. The cells are collected inside the needle lumen.”