A phlebotomist should instruct a patient to take which of the following actions when providing a sputum specimen?

Choice A Reason:
Signing a release for laboratory results is a form of expressed consent, not implied consent. Expressed consent is given explicitly, either orally or in writing, and is clearly and unmistakably communicated. It involves a clear action of agreement to the specific procedure or intervention proposed.

Choice B Reason:
Signing a document of agreement for a research study is also an example of expressed consent. The patient is actively agreeing to participate in the study, which is a direct and informed action. This type of consent is necessary for research studies to ensure that participants are fully aware of the study's nature and any potential risks involved.

Choice C Reason:
Implied consent occurs when a patient's actions suggest consent without verbal or written confirmation. Offering an arm to a phlebotomist is a non-verbal communication that implies the patient is willing to have their blood drawn. This is a common practice in medical settings where the action of presenting an arm indicates readiness for the procedure.

Choice D Reason:
A family member nodding for a phlebotomist to proceed does not constitute the patient's implied consent. Consent must come directly from the patient unless they are unable to provide it, in which case a legal surrogate may give consent on their behalf. The nod of a family member cannot be assumed as the patient's consent.

Choice A Reason:
For blood donation, a 16- to 18-gauge needle is typically used because it is large enough to allow the rapid flow of blood without causing hemolysis (destruction of red blood cells). The larger gauge needle also helps in minimizing the time the donor has to spend during the donation process. Using a needle that is too small could slow down the blood flow and potentially damage the blood cells, which is not ideal for the recipient of the blood donation.

Choice B Reason:
A 19- to 21-gauge needle is commonly used for routine venipuncture but is not ideal for blood donation. These needles are smaller than the 16- to 18-gauge needles and would not facilitate the quick collection of the volume of blood typically required for a donation. They are more suitable for collecting blood samples for testing rather than for donation purposes.

Choice C Reason:
A 22- to 24-gauge needle is even smaller and is often used for patients with smaller veins, such as children or elderly patients. These needles would not be appropriate for blood donation as they could significantly slow the blood flow and increase the donation time, which could be uncomfortable for the donor.

Choice D Reason:
A 25- to 28-gauge needle is the smallest size commonly used in medical practice and is suitable for patients with extremely small or fragile veins. These needles would be impractical for blood donation due to their small size, which would not allow for the efficient flow of blood required for a donation.