Final answer:
A drug screen is the specimen that requires chain-of-custody documentation to maintain the integrity of the results for potential legal implications.
Step-by-step explanation:
The specimen that may require chain-of-custody documentation when it is collected is a drug screen. Chain-of-custody documentation is critical in situations where the test results could have legal implications, such as in the case of drug screening for employment, sports doping tests, or legal investigations. This documentation ensures that the sample is handled and analyzed in a documented and unbroken process from collection to reporting of results, to maintain the integrity and credibility of the results.
Other specimens like trace elements, cross-match, and blood cultures, although important for diagnostic or therapeutic purposes, typically do not require chain-of-custody documentation as their results do not usually have legal consequences.