The purpose of pre‐operative skin preparation is to remove visible contaminants and to reduce the levels of naturally occurring skin flora, particularly Staphylococcus aureus, so as to reduce the risk of surgical site infection (Wicker and O'Neill [228]). Surgical site preparation is the treatment of the intact skin of the intended surgical site and surrounding area, and this takes place once the patient is in the operating room, on the operating table (Allegranzi et al. [12]).

Normal bacterial flora live in the nose, groin, armpit, gut, skin and hair of everybody. Organisms may become pathogenic when they move out of their normal area on the body to an open wound (Wicker and O'Neill [228]). NICE ([150]) guidelines advise patients to shower or have a bath using soap either the day before or on the day of surgery. While there is no evidence concerning patient theatre attire, NICE ([150]) advises that patients are given a clean theatre gown to wear and asked to remove their own clothing (depending on the operation). Theatre gowns should maintain the patient's comfort and dignity while allowing easy access to the operative site. Furthermore, theatre gowns avoid placing the patient's own clothes at risk of contamination from blood, body fluid and washout fluids (Pudner [168]).

The most widely used antiseptic skin preparation agents are 2% chlorhexidine gluconate and iodophors (e.g. povidone‐iodine) in alcohol‐based solutions. These are effective against a wide range of bacteria, fungi and viruses (NICE [150]). NICE ([150]) has set out recommendations for surgical site preparation; these can be found in Table 16.5. Currently, some preparation solutions also contain colouring agents, which are helpful for indicating where the products have been applied (WHO [226]).