The World Health Organization published its Global Guidelines for the Prevention of Surgical Site Infection in 2016, then updated them in 2018. These guidelines remain the current WHO standard and cover the full surgical timeline, from preoperative preparation through wound closure. They include 29 recommendations spanning antibiotics, skin prep, temperature control, blood sugar management, oxygenation, sutures, and more. Here’s what the guidelines actually say and what each recommendation means in practice.
Preoperative Antibiotics: Timing and Duration
Antibiotics should be given within 120 minutes before the surgeon makes the first incision. This window applies to most standard antibiotics. For drugs that require a slower infusion, such as vancomycin, the infusion needs to start earlier to ensure the drug is fully delivered before the procedure begins.
Within that two-hour window, no single narrower interval has proven better than another. A meta-analysis of six studies found no meaningful difference in infection rates between antibiotics given 60 to 120 minutes before incision versus those given in the final 60 minutes. Similarly, giving them in the last 30 minutes showed no advantage over the 30-to-60-minute window. The key is staying inside the 120-minute boundary, not hitting a precise minute.
After surgery, the WHO recommends stopping prophylactic antibiotics entirely once the wound is closed. This applies even when a surgical drain is left in place. There is no evidence that continuing antibiotics until drains or devices are removed reduces infection. Multiple organizations, including the Infectious Diseases Society of America and the Society for Healthcare Epidemiology of America, echo this position, generally capping postoperative antibiotics at 24 hours maximum for procedures where any extension is considered.
Skin Preparation Before Incision
The WHO guidelines recommend using an alcohol-based antiseptic solution to clean the skin at the surgical site. Both chlorhexidine gluconate in alcohol and povidone-iodine in alcohol are considered effective. A large trial published in JAMA comparing the two in cardiac and abdominal surgery found povidone-iodine in alcohol was noninferior to chlorhexidine in alcohol. In cardiac procedures, infection rates were 4.2% with povidone-iodine versus 3.3% with chlorhexidine. In abdominal surgery, the pattern reversed: 6.8% with povidone-iodine versus 9.9% with chlorhexidine. The practical takeaway is that either antiseptic works well as long as it’s combined with an alcohol base.
Hair Removal: Clippers, Not Razors
If hair needs to be removed from the surgical site, the WHO strongly recommends clippers over razors. A meta-analysis of four studies found that clipping cut the risk of infection roughly in half compared to shaving with a razor (odds ratio: 0.51). Razors create tiny nicks and abrasions in the skin that become entry points for bacteria. Clipping avoids this trauma. A broader analysis pooling ten studies confirmed the finding: clipping or leaving hair in place was significantly safer than shaving.
Timing is less critical than method. One study comparing hair removal the night before surgery to removal on the day of surgery found no difference in infection rates. The WHO does suggest that if hair removal is necessary, it should happen in the operating room rather than the night before, but the strongest recommendation is simply to avoid razors altogether.
Body Temperature During Surgery
Patients who get cold during surgery face a higher risk of surgical site infection. The WHO guidelines recommend actively maintaining body temperature at or above 36°C (96.8°F) throughout the procedure, with warming devices like forced-air blankets. Various guidelines set the lower limit between 35.5°C and 36°C, and clinical protocols typically aim to keep core temperature near 36.5°C.
Hypothermia impairs the immune cells that fight bacteria at the wound site and reduces blood flow to the skin, slowing the delivery of oxygen and antibiotics to the tissue. Active warming is a straightforward, low-risk intervention that surgical teams can apply to virtually every patient.
Blood Sugar Control
High blood sugar during and after surgery increases infection risk regardless of whether you have diabetes. The WHO guidelines recommend intensive blood glucose monitoring and control in the perioperative period. The widely accepted target range is 140 to 180 mg/dL (7.7 to 10 mmol/L). This range is endorsed across multiple professional societies, including the American Diabetes Association, the Endocrine Society, and the Society of Thoracic Surgeons.
For cardiac surgery patients specifically, postoperative blood glucose should stay between 140 and 180 mg/dL. Tighter control (110 to 140 mg/dL) may be appropriate for some patients, but only if it can be achieved without causing dangerously low blood sugar. The British guidelines set a slightly broader acceptable range of 72 to 216 mg/dL, with a target of 108 to 180 mg/dL.
Supplemental Oxygen for Intubated Patients
The WHO recommends that adults under general anesthesia with a breathing tube receive a high concentration of oxygen, specifically 80%, during surgery and for two to six hours afterward. Higher oxygen levels in the blood help white blood cells kill bacteria more effectively at the wound site.
This recommendation applies to patients undergoing routine elective surgery. It does not extend to emergency operations or critically ill patients, who may actually fare worse with high oxygen levels. Known tradeoffs include a type of lung collapse called absorptive atelectasis, where high oxygen concentrations cause small air sacs in the lungs to deflate. For scheduled surgeries in otherwise stable patients, the evidence favors the higher oxygen approach.
Bowel Preparation for Colorectal Surgery
For patients undergoing elective colorectal surgery, the WHO and other organizations recommend combining mechanical bowel preparation (the traditional bowel “cleanse”) with oral antibiotics before surgery. The American Society of Colon and Rectal Surgeons gives this a strong recommendation, and the ERAS (Enhanced Recovery After Surgery) society concurs.
One important nuance: oral antibiotics should not be given on their own without mechanical preparation. The combination works together to reduce the bacterial load in the colon before it’s opened during surgery. Oral antibiotics alone, without the mechanical cleanse, are not recommended.
Antimicrobial-Coated Sutures
The WHO, CDC, and UK National Institute for Health and Care Excellence all suggest considering sutures coated with an antimicrobial agent (triclosan) for wound closure. A 2025 meta-analysis of 31 randomized trials involving nearly 18,000 patients found that these coated sutures reduced surgical site infections by 25% compared to standard sutures (relative risk: 0.75). The evidence was rated as moderate certainty, which is why the guidelines frame this as something to “consider” rather than mandate for every procedure.
Nutritional Support Before Surgery
The guidelines recognize that malnourished patients face a higher risk of wound infection. Oral nutritional supplements containing protein, amino acids like arginine and glutamine, omega-3 fatty acids, and key vitamins and minerals can improve immune function and wound healing. These supplements are typically recommended when a patient is assessed as nutritionally at risk before surgery. Protein-enriched formulas and those containing arginine have the most evidence behind them for reducing infection risk specifically.
How the Guidelines Fit Together
The WHO framework treats infection prevention as a chain of linked steps rather than any single intervention. Preoperative measures (antibiotics, skin prep, hair removal, nutrition) reduce the bacterial load and prepare the body. Intraoperative measures (oxygenation, temperature control, blood sugar management, wound irrigation) create conditions where the immune system can work effectively and bacteria struggle to establish themselves. Postoperative measures (stopping unnecessary antibiotics, using coated sutures) minimize both infection risk and the development of antibiotic resistance.
The 2018 update remains the current WHO standard. While individual countries and surgical societies have layered their own recommendations on top, the WHO guidelines serve as the global baseline. They are designed to apply across resource settings, from high-income hospitals with advanced monitoring to facilities with more limited equipment, making the recommendations deliberately practical and broadly implementable.