Preoperative timing for antibiotic prophylaxis?

Preoperative timing for antibiotic prophylaxis?

• A. Two hours before incision
• B. After incision
• C. Within 60 minutes before incision
• D. Immediately after incision

Answer: (C)

The key idea is to have the antibiotic present in the tissues at the moment the incision is made, so the wound is protected right from the start of exposure to potential contamination. Giving the prophylactic antibiotic within 60 minutes before incision ensures that tissue levels peak or are near peak when the skin is cut, which reduces the risk of surgical-site infection as the wound is opened and early contamination can occur. If you give the drug too early, its tissue levels may decline by the time the incision happens, so protection wanes. If you wait until after the incision, you miss the critical window when the wound is first exposed. Some antibiotics with longer infusion times, like vancomycin or certain fluoroquinolones, are given within about 120 minutes before incision to finish the infusion prior to incision, but for most standard prophylaxis this window is 60 minutes. In longer surgeries or those with substantial blood loss, you may need to redose to maintain protective levels throughout the procedure.

The key idea is to have the antibiotic present in the tissues at the moment the incision is made, so the wound is protected right from the start of exposure to potential contamination. Giving the prophylactic antibiotic within 60 minutes before incision ensures that tissue levels peak or are near peak when the skin is cut, which reduces the risk of surgical-site infection as the wound is opened and early contamination can occur.

If you give the drug too early, its tissue levels may decline by the time the incision happens, so protection wanes. If you wait until after the incision, you miss the critical window when the wound is first exposed. Some antibiotics with longer infusion times, like vancomycin or certain fluoroquinolones, are given within about 120 minutes before incision to finish the infusion prior to incision, but for most standard prophylaxis this window is 60 minutes.

In longer surgeries or those with substantial blood loss, you may need to redose to maintain protective levels throughout the procedure.