NHCO Order of Draw Practice Test

STS tubes contain Sodium polyanetholesulfonate, the additive used to preserve circulating organisms for blood cultures. This compound acts as an anticoagulant and helps keep bacteria alive by binding calcium and inhibiting certain immune processes, which is why these tubes are chosen for culture work. They are not tan-colored; blood culture tubes with this additive are typically yellow-top. They are also not used for ABO typing, which relies on different tubes and reagents. So the statement naming the additive, Sodium polyanetholesulfonate, is the correct description of STS tubes.