A phlebotomist should explain the procedure prior to venipuncture to:

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:
When a patient is under "Contact Precautions," it is recommended that healthcare workers don a gown upon entering the patient's room. This is to prevent the spread of infection through contact with the patient or their environment. The gown should be removed before leaving the room to avoid contaminating other areas.

Choice B Reason:
While a face shield may be necessary for certain procedures, it is not specifically required for "Contact Precautions." The primary concern with contact precautions is preventing the transmission of infections through touch, not through droplets, which is what a face shield would protect against.

Choice C Reason:
Donning a mask is not a standard requirement for "Contact Precautions" unless there is a risk of droplet transmission. In this scenario, the precautions are specifically for contact, and therefore, a mask alone would not be sufficient.

Choice D Reason:
Gloves should be donned before any potential contact with the patient or their immediate environment, not just after cleaning and evaluating the venipuncture site. Gloves are a critical component of PPE when dealing with patients under "Contact Precautions."