Which of the following tests does NOT require a chain of custody?

The correct answer is that fetal fibronectin testing does not require a chain of custody. This test is primarily used in obstetrics to help assess the risk of preterm labor. Fetal fibronectin is a protein found in the tissues that connect the fetus to the uterus, and its presence or absence in cervicovaginal fluid can indicate the likelihood of prematurity. The testing process does not usually involve legal implications or the necessity for strict handling procedures that are essential in tests meant to provide evidence in judicial contexts.

In contrast, legal blood alcohol tests, paternity testing, and pre-employment drug screens all have significant legal implications and require a meticulously documented chain of custody. In these cases, it's critical to ensure that the sample is correctly identified and tracked during every stage of processing to maintain its integrity and admissibility in legal proceedings. This strict protocol helps to prevent any claims of tampering or contamination, which could undermine the validity of the test results in a legal context.