When should prophylactic antibiotics be given relative to incision?

When should prophylactic antibiotics be given relative to incision?

• A. Within 60 minutes before incision
• B. 24 hours before incision
• C. During incision only
• D. After incision has begun

Answer: (A)

Prophylactic antibiotics are timed so that their tissue concentrations are high right when the incision is made, to prevent bacteria from establishing infection as the wound is opened. For most antibiotics, the best window is within about an hour before incision, so the drug is active in the tissues at the moment of incision. If given 24 hours before, drug levels would have fallen by the time surgery starts, offering little protective effect and potentially increasing risks. Administering during or after incision means the wound is already exposed, so the antibiotic isn’t in place to prevent contamination. (Some drugs that require longer infusion times may be started earlier to finish by incision, but for standard prophylaxis the recommendation is within an hour before incisions.)

Prophylactic antibiotics are timed so that their tissue concentrations are high right when the incision is made, to prevent bacteria from establishing infection as the wound is opened. For most antibiotics, the best window is within about an hour before incision, so the drug is active in the tissues at the moment of incision. If given 24 hours before, drug levels would have fallen by the time surgery starts, offering little protective effect and potentially increasing risks. Administering during or after incision means the wound is already exposed, so the antibiotic isn’t in place to prevent contamination. (Some drugs that require longer infusion times may be started earlier to finish by incision, but for standard prophylaxis the recommendation is within an hour before incisions.)