Choice A reason:

Choice A Reason:
The recommended heel stick depth of 2.0 mm is based on the need to minimize the risk of injury to the infant. Penetrating deeper than this can increase the likelihood of hitting bone, which in infants can be as close as 2.0 mm under the skin of the plantar surface of the heel. This depth is sufficient to obtain a blood sample without risking injury to deeper tissues or bone.

Choice B Reason:
A depth of 2.5 mm may be too deep for some infants, especially preterm or very small infants, where the calcaneus (heel bone) is closer to the surface. While this depth might still be safe for some infants, it does not provide the same margin of safety as the 2.0 mm recommendation and could potentially lead to bone puncture or other injuries.

Choice C Reason:
A depth of 3.0 mm significantly increases the risk of bone puncture, especially in infants with less subcutaneous fat or in those who are preterm. This depth could easily breach the protective layer of skin and subcutaneous tissue, leading to a higher risk of osteomyelitis, an infection of the bone, which can be a serious complication in infants.

Choice D Reason:
A depth of 3.5 mm is considered too deep for a heel stick procedure and is likely to cause injury to the infant. This depth would almost certainly penetrate the bone in most infants, leading to severe pain, potential for infection, and other complications. It is well beyond the safe range recommended by CLSI and should be avoided.

Choice A Reason:
The chain of custody form is crucial in the context of a toxicology drug screen for legal purposes. It is a document that records the sequence of custody, control, transfer, analysis, and disposition of physical and electronic evidence. It is particularly important in legal cases where the results of the toxicology screen can be used as evidence in court. The chain of custody ensures that the sample has been handled properly and that the integrity of the sample has been maintained throughout the testing process.

Choice B Reason:
A requisition form is used to request a specific test or service. While it is an essential document in the process of ordering a toxicology drug screen, it does not serve the same purpose as the chain of custody in terms of legal proceedings. The requisition form typically includes patient information, the tests ordered, and the reason for the test, but it does not track the handling of the sample.

Choice C Reason:
An encounter form, also known as a superbill, is used in medical billing to capture the services provided during a patient's visit. It includes information about the patient's diagnosis, the procedures performed, and the codes for billing purposes. However, it is not specifically related to the legal aspects of a toxicology drug screen.

Choice D Reason:
The CMS 1500 form is the standard claim form used by healthcare providers to bill Medicare and Medicaid services. It is also used by some private insurers and managed care plans. Like the encounter form, it is related to billing and not to the legal chain of custody required for a toxicology drug screen.