Final answer:
For neonatal metabolic disorder testing, a heel stick blood collection card is used. Among tube choices, a red top tube is appropriate for serology tests like the VDRL, which identifies a flocculant reaction.
Step-by-step explanation:
The collection container used to test neonates for certain metabolic disorders is a heel stick blood collection card, often referred to as a Guthrie card. For newborn screening tests, including those for metabolic disorders, blood is typically collected on a special filter paper card designed for dried blood spot sampling. However, among the tube options provided in the question - red top tube, green top tube, lavender top tube, and yellow top tube - the correct choice for collecting blood for certain tests including VDRL (Venereal Disease Research Laboratory) test, which is used to screen for syphilis, is the red top tube. This tube is commonly used for serology and immunology testing since it allows the blood to clot and produce serum for analysis. It does not contain anticoagulants, which is suitable for the VDRL test where a flocculant reaction is observed.