What Is the Yellow Test Tube for Phlebotomy?

The yellow tube used in phlebotomy collects a specimen for a blood culture. This plastic vacutainer tube is drawn first. Other phlebotomy tubes have a variation in yellow color, including yellow/black top, gold top, and pale yellow top indicating use for different blood tests.

Pale yellow-top tubes contain an additive called ACD, or acid-citrate-dextrose. This tube is used for HLA tissue typing, paternity testing and other studies of genetics.

Sometimes phlebotomoy tubes have yellow/black tops. The tube contains a broth mixture used in cultivating organisms in a blood culture. Blood cultures grow microorganisms existing in the blood to examine which micro-organism is the culprit for infection. The broth mixture provides nutrients to aerobic and anaerobic bacteria, as well as fungi. Lab technicians report their findings to other health professionals, which determine the course of treatment.

Gold-top vacutainer tubes can be mistaken for yellow-top tubes but serve a very different function. Phlebotomists utilize gold-top tubes to collect specimens for the analysis of blood chemistries, immunology and serological testing. Gold tubes work via a serum separator tube. The plastic tube contains a gel at the bottom that separates blood from serum when put in a centrifuge. These tubes need to be mixed well after collecting the blood sample.