Holes in sterile wrap and their implications for sterile processing
Surgical site infections (SSIs), the most frequent type of healthcare-associated infections (HAIs), are known to occur up to 30 days after surgery and affect either the incision or deep tissue at the operation site.
Infection during surgery
Approximately 10 percent of patients who have surgery in low- and middle-income countries (LMICs) acquire SSIs. ,  This undesirable effect can be a significant clinical problem, as SSIs dramatically increase the direct and indirect cost of treatment and reduce the health-related quality of life.  Numerous patient-related and procedure-related factors are known to influence the risk of SSIs.
The role of reusable surgical instruments
Reusable surgical instruments represent one potential route for the transmission of pathogens, as they are contaminated with blood and microorganisms to varying degrees after every operation.  Guidelines recommend that reusable surgical instruments should be sterilized between uses. , ,  Therefore, from use to reuse these instruments go through a complex decontamination journey; a vital component in the prevention of HAIs. This reprocessing of medical instruments involves transfer, pre-cleaning and decontamination, preparation and maintenance, packaging, sterilization, and storage until the moment of use. , 
Challenges during / After sterilization
Methods of instrument sterilization include steam and low temperature sterilization. During the process the instruments can either be wrapped in sterilization wrap or placed into rigid containers.  A considerable number of instrument sets are wrapped. However, if wraps are damaged by the instruments or trays they are holding, the sterilization process needs to be repeated. On average, 5 percent of wrapped instrument sets are reprocessed due to tears.  Damaged sterile packages or wet sets might cause operating room downtimes and time pressure. Moreover, holes in wraps might appear without discrimination and might be overlooked. In that case they represent a serious risk factor for SSIs.
Detection of holes in the sterilization packaging
There appears to be difficulty detecting holes in sterile wrappings that are less than 2 mm in size. As Waked et al. found out in a 2007 survey, defects with a diameter of 6.7 mm were missed 18 percent of the time. At the same time they could prove that puncture holes as small as 1.1 mm could transmit contaminates through the wrapping material.  In 2018, Rashidifard et al. repeated the analysis with a larger sample size and under various conditions.  The study included 30 surgical personnel from two different hospitals and was comprised of surgical technicians, operating room nurses, and orthopedic surgery residents. 9 different defect sizes between 0.86 mm and 5.0 mm were pierced into completely sterile wraps using different tools. Sterile wrap inspection was conducted by unwrapping the sterile dressing, lifting it to a light source in the operating room, and identifying any perforations that may compromise sterility. The study group corroborated the results from 2007; holes with a diameter of 2.5 mm were detected more often than holes with a diameter of 2 mm.
When looking at the different parameters, there was no difference in detection accuracy between using an operating room lamp or ambient lightning. The level of experience of the inspector (0-9 years, 10-20 years or >20 years) did not significantly change the detection results. Neither did the study group document a correlation between inspection time and detection accuracy. In every situation, defects with a diameter of ≤ 2 mm were not reliably detected (Figure 1). Further research should assess and determine the level of contamination that could be expected through small holes that are generally invisible to the eye. Both detected and undetected holes represent a major problem for any hospital in terms of patient safety, time consumption and stress in the operation room, and finally hospital reputation.
Addressing obstacles to the effective sterilization process
Increasing the number of sterile wrap layers does not seem to address the problem sufficiently. Webster et al. reported in 2005 that double-wrapping sterile instrument packs increased costs and did not reduce the risk for tray contamination.  Other options for optimizing the process include more detailed training for detecting compromised wraps, modified wrapping or an alternative option for sterilization like reusable rigid container. Despite higher investment costs, sterile containers catch up with the soft packaging at a certain timepoint due to lower operating cost, as a just recently published analysis demonstrated: Even under a broad set of scenarios a sterile container is the most cost-effective alternative when compared to "one-step sterilization wrap" and "two sheets sterilization wrap".  Owing to the possibility of nondetectable holes in wraps the sterile container provides a reliable alternative with less waste and economic benefits. The goal is to define an efficient and reliable process, that aids to provide consistent patient care, smooth operating room processes without interruptions and additional stress and avoids unnecessary reprocessing of instruments.
 WHO Protocol for surgical site infection surveillance with a focus on settings with limited resources, 2018; http://www.who.int/infection-prevention/en/.
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 Rutala WA, Weber DJ. Healthcare Infection Control Practices Advisory Committee. Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008. Atlanta: CDC; 2008.
 Department of Health. Choice Framework for Local Policy and Procedures 01-01 e Management and decontamination of surgical instruments (medical devices) used in acute care. Part C e Steam sterilization. London: DH; 2013.
 World Health Organization. WHO guidelines for safe surgery 2009: safe surgery saves lives. Geneva: WHO; 2009.
 Waked WR, Simpson AK, Miller CP, Magit DP, Grauer JN. Sterilization wrap inspections do not adequately evaluate instrument sterility. Clin Orthop Relat Res. 2007; 462:207–211.
 Rashidifard CH, Mayassi HA, Bush CM, Opalacz BM, Richardson MW, Muccino PM, DiPasquale TG. Looking for Holes in Sterile Wrapping: How Accurate Are We? Clin Orthop Relat Res 2018; 476:1076-1080.
 Webster J, Radke E, George N, Faoagali J, Harris M. Barrier properties and cost implications of a single versus a double wrap for storing sterile instrument packs. Am J Infect Control. 2005; 33:348–352.
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Infographic as poster download
Holes in sterile wrapping – an unseen risk
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