Erasmus University Medical Center Rotterdam - Department of Neurosurgery, Erasmus University Medical Center Rotterdam - Department of General Surgery, Maastricht University - Department of Gynecology, Dutch National Guideline Group for Prevention of Postoperative Surgical Site Infections, Erasmus University Rotterdam (EUR) - Erasmus School of Health Policy & Management, Erasmus University Medical Center Rotterdam - Department of General Surgery, Utrecht University - Department of Cardiothoracic Surgery, University of Amsterdam - University Medical Center, Leiden University - Department of Neurosurgery, Leiden University - Leiden Law School, Erasmus University Medical Center Rotterdam - Department of Cardiology, University of Amsterdam - Department of Neurosurgery, Erasmus University Rotterdam (EUR) and University of Amsterdam - Department of Neurosurgery