A cannula (10) for use in removing samples of fluid from a container sealed with a pierceable membrane, the cannula including a hollow needle like portion (12) having a pointed forward end (20) shaped to allow forcible penetration through the membrane, the rear end (14) having a first bore (26) and an insert (40) located within the first bore (40) that reduces the effective size of the first bore (26) without blocking the first bore (26).
