Final answer:
The statement 'only items that become contaminated must be replaced' is not a correct guideline for working in a sterile field, as all potential breaches require replacement of the item to maintain a sterile environment.
Step-by-step explanation:
Between the provided choices, the statement d. only items that become contaminated must be replaced is NOT a guideline for working in a sterile field because in a sterile environment, extraordinarily stringent guidelines dictate that if there is any doubt about the sterility of an item, it should be considered contaminated and be replaced, regardless of whether direct contamination is confirmed. Guidelines for maintaining a sterile field generally include ensuring that: a. items are considered contaminated if they touch skin or clothing, b. one should never reach across a sterile field, and c. sterile fields must be kept dry. Any potential breach of sterility requires action, even if actual contamination is not visually evident.
In a clinical setting, protocols ensure that items categorized as critical, such as surgical instruments and intravenous fluids, must be sterile because they penetrate sterile tissues or enter the bloodstream. Semicritical items like gastrointestinal endoscopes require a high level of disinfection but not necessarily sterilization, and noncritical items that come into contact with but do not penetrate intact skin require cleanliness without high-level disinfection.