Preoperative hair removal to reduce surgical site infection (2024)

Monitoring Editor: Cochrane Wounds Group, Judith Tanner, and Kate Melen

Does hair removal before surgery prevent infections after surgery?

Key messages?

Compared with no hair removal:

· there are probably more surgical site infections when hair is removed by shaving with a razor;

· removing hair with clippers and cream may make little to no difference to the number of infections;

Clippers and hair removal cream probably cause fewer infections than shaving using a razor.

Removing hair on the day of, rather than the day before surgery may slightly reduce the number of infections.

Why is hair removed before surgery?

Before a surgical intervention, it is common to remove hair from the area of the body that is going to have surgery. Hair can be removed using different methods, including clippers, a razor, or hair removal cream.

Hair is removed to avoid problems during and after surgery, for example when stitching up wounds or applying dressings. However, some studies claim that removing hair could cause infections after surgery and should be avoided.

What did we want to find out?

We wanted to find out if removing hair before surgery:

· causes or prevents infections;

· prevents wound complications, such as cuts to the skin or the opening up of stitched wounds;

· has an impact on how long people stay in hospital after surgery; and

· has any cost implications.

We were also interested in whether some hair removal methods or times for hair removal are better than others.

What did we do?

First, we searched for studies that compared:

· hair removal against no removal; or

· different methods and times of hair removal.

We then compared the results and summarised the evidence from all the studies. Finally, we rated our confidence in the evidence, based on factors such as study methods and sizes.

What did we find?

We found 25 studies that involved a total of 8919 people.

Ten studies compared no hair removal against hair removal, using:

· clippers (3 studies);

· shaving with a razor (8 studies, 7 of which provided useable evidence); or

· hair removal cream (1 study).

Seven studies compared using a razor against using clippers, and 10 studies compared using a razor against using cream (nine of these 10 studies provided useable evidence).

One study compared hair removal the day before surgery versus hair removal on the day of surgery.

What does the evidence show?

Hair removal compared to no hair removal

· Hair removal with clippers and cream may make little to no difference to the number of surgical site infections.

· Hair removal with a razor probably risks more infections than no hair removal.

Whether hair is removed with a razor or not removed may make little to no difference for length of hospital stay (1 study).

Comparisons of different hair removal methods

· Clippers probably cause fewer infections and skin injuries than razors.

· Cream probably causes fewer infections, and may cause fewer skin injuries, than razors.

Time of hair removal

Whether hair is removed on the day of surgery or the day before surgery may slightly reduce infection numbers (1 study).

What do we still not know?

Due to a lack of robust studies, we do not know:

· if removing hair affects wound complications and costs when compared to not removing hair;

· if different hair removal methods have different effects on length of hospital stay, or on costs; and

· if the time of hair removal affects wound complications, length of hospital stay, or costs.

How up‐to‐date is this review?

The evidence in this Cochrane Review is current to November 2019.

Description of the condition

The preparation of patients for surgery has traditionally included the routine removal of body hair from the intended surgical incision site. Hair is removed because its presence can interfere with the exposure of the incision site, the suturing of the incision, and the application of adhesive drapes or wound dressings (Hallstrom 1993; Miller 2001). Hair is also perceived to be associated with a lack of cleanliness, and the removal of hair is thought to reduce the risk of surgical site infections (SSIs) (Kumar 2002). However, some studies claim that preoperative hair removal is not beneficial and perhaps even contributes to SSIs, and therefore should not be carried out (Cruse 1973; Powis 1976; Seropian 1971).

A surgical site infection is an infection that occurs in the operative site within the 30 days following surgery, or up to one year if there is an implant. It can involve skin and subcutaneous tissue (superficial incisional), and/or deep soft tissue (deep incisional), and/or any part of the anatomy (organ/space) (WHO 2018b). SSIs develop when bacteria from the person having the surgery, the staff, equipment, or the environment enter the incision site during surgery (WHO 2018b). SSIs are a global problem that is estimated to affect millions of people each year (WHO 2011) The World Health Organization (WHO) reports the incidence of SSI ranging from 1.2% to 23.6% in low‐ and middle‐income countries, and 1.2% to 5.2% in high income countries (WHO 2011). SSIs are distressing for patients and can be extremely costly to treat, resulting in delayed wound healing, unnecessary pain, and, in extreme cases, death (Adams‐Howel 2015; Awad 2012; Brown 2014; Plowman 2000).

Description of the intervention

Three main methods of hair removal are currently used in healthcare settings: shaving with a razor, clipping, and chemical depilation. Shaving uses a sharp blade, held within the head of a razor, which is drawn over the patient's skin to cut hair close to the surface of the skin. A traditional ‘safety razor’ uses a single blade which cuts hair at the level of the skin. Multiblade razors use at least two blades to give a ‘closer shave’, cutting hair below the level of the skin. The first blade catches the hair and tugs it taut, whilst the second blade slices the hair which, when it goes slack, falls back slightly below the skin surface (Huguenin 2017). Disposable razors are available.

Clippers use sharpened comb‐like blades which cut hair between the teeth of the comb in a scissor‐like action. Hair is cut close to the patient's skin, leaving a short stubble. The length of stubble depends on the cutting blade or guard used (Wahl 2005). The heads of clippers can be disposed of after use to minimise the risks of cross‐infection.

Depilatory creams contain alkaline‐based chemicals that break down the keratin within the hair. This thins and weakens the hair so that it breaks at its base just below the surface of the skin and can be wiped away. This is a slower process than either shaving or clipping, as the cream has to remain in contact with the hair for between five and 10 minutes depending on the thickness of the hair. There is a risk of irritation or allergic reactions to the cream, so patch tests should be carried out before the first time the cream is applied over a larger area (Veet 2020).

How the intervention might work

During the process of shaving with a razor, the skin may sustain microscopic cuts and abrasions. It is suggested that micro‐organisms are able to enter and colonise these cuts, thus contaminating the surgical incision site and causing SSIs (Briggs 1997). In addition, abrasions may exude tissue fluid, which provides a culture medium for micro‐organisms (Seropian 1971). As clipper blades do not come into contact with people's skin, they are postulated to reduce the risk of cuts and abrasions (Fogg 2003). Similarly, depilatory cream is not abrasive to skin. Shaving and clipping can be carried out in operating theatres, anaesthetic rooms, wards, or in patients' homes by theatre staff, ward staff, or by the patients themselves. Chemical depilation is usually carried out in patients' homes, as it usually requires pre‐application testing (Veet 2020). However, research suggests that hair removal should not take place in the operating theatre, as loose hair may contaminate the sterile surgical field (Edmiston 2016). Others have suggested that hair removal should be carried out by skilled personnel to prevent abrasion injuries (Hallstrom 1993; Small 1996).

Why it is important to do this review

Having a hairless surgical field may ease surgery and make it easier to apply adhesive drapes or dressings, but could increase infection rates. Recommendations for hair removal published by professional organisations in the late 1990s and early 2000s (which have been updated since) varied slightly, and some were based upon observational studies as well as randomised trials (Kjonniksen 2003). The initial version of this review, Tanner 2006, collated data from randomised trials identified through a systematic literature review without language restrictions to identify the benefit or harm of removing hair using different methods. Most of the evidence for outcomes for hair removal practices published in the initial review, Tanner 2006, and the previous update, Tanner 2011, were supported by low‐ or very low‐certainty evidence, and in some instances there was no supporting evidence (e.g. clippers versus cream). Since 2011, several new trials of preoperative hair removal to reduce surgical site infection have been published. An updated systematic review was required to summarise and present the best evidence.

Criteria for considering studies for this review

Search methods for identification of studies

Data collection and analysis

We carried out data collection and analysis according to the methods stated in the published protocol (Tanner 2003), which were based on the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2019). Changes from the protocol or previous published versions of this review are documented in Differences between protocol and review.

Description of studies

For details of individual studies, see Characteristics of included studies and Characteristics of excluded studies.

Risk of bias in included studies

See the 'Risk of bias' graph (Figure 1) and 'Risk of bias' summary (Figure 2).

It was not possible for a study to be at low risk of performance bias (blinding of participants), as it would have been obvious to participants if they had had hair removed, and also by which method if they were conscious at the time of removal. This risk of bias was therefore unavoidable, but we judge that the primary or secondary outcomes were unlikely to have been influenced by lack of blinding. Similarly, the blinding status of caregivers was also considered unlikely to influence primary or secondary outcomes, as hair removal would take place in pre‐ or intraoperative settings, which are likely staffed by a different set of staff from the postoperative setting. Additionally, hair would grow back within a few days, and caregivers would be unable to tell whether hair was removed or by which method. We considered one trial to be at low risk of bias (Kowalski 2016). Six QRCTs, Breiting 1981; Ko 1992; Lu 2002; Powis 1976; Seropian 1971; Thur de Koos 1983, and five RCTs, Celik 2007; Domes 2011; Grober 2013; Karegoudar 2012; Taylor 2005, were considered to be at high risk of bias and were excluded from sensitivity analyses.

Effects of interventions

See: Table 1; Table 2; Table 3; Table 4; Table 5; Table 6

See: 'Summary of findings' tables for the following comparisons; clipping versus no hair removal (Table 1), shaving with a razor versus no hair removal (Table 2), depilatory cream versus no hair removal (Table 3), shaving with a razor versus clipping (Table 4), shaving with a razor versus cream (Table 5), and hair removal on the day before surgery versus hair removal on the day of surgery (Table 6). One trial, Ilankovan 1992, did not provide sufficient outcome data to be included in a meta‐analysis, and Karegoudar 2012 did not provide sufficient outcome data to be included in either a narrative synthesis or meta‐analysis. We note that where data were pooled we used random effects models, meaning the estimates presented are average effect estimates and should be interpreted as such.

Summary of main results

The objectives of this review were to determine whether routine preoperative hair removal (compared with no removal) and the method, timing, or setting of hair removal influence rates of SSI.

There may be little to no difference in SSIs whether hair is not removed or removed with clippers (low‐certainty evidence). A sensitivity analysis of this comparison also suggests there may be little to no difference in SSIs (low‐certainty evidence). SSIs are probably lower when hair is not removed rather than removed with a razor (moderate‐certainty evidence), although in a sensitivity analysis the confidence intervals narrowly include the possibility of no effect or harm (moderate‐certainty evidence). Low‐certainty evidence for the comparison of no hair removal with hair removal with depilatory cream suggests there may be little difference in SSIs.

When comparing different methods of hair removal, there is moderate‐certainty evidence that SSIs are probably lower when clippers or depilatory creams are used rather than shaving with razors. A subgroup analysis comparing clippers with razors on male genitalia found that it was unclear whether there was a difference in SSIs in this specific anatomical region, based on very low‐certainty evidence.

There may be a small reduction in SSIs when hair is removed on the day of surgery compared with the day before surgery (low‐certainty evidence).

Based on low‐certainty evidence, it is unclear whether there is a difference in the incidence of wound complications between no hair removal and hair removal with a razor, although moderate‐certainty evidence suggests the risk of skin injury is probably lower in participants who have hair removed (from their body as opposed to male genitalia) with clippers and may be lower (low‐certainty evidence) when using cream compared with razors. Low‐certainty evidence suggests that razors may result in fewer injuries to scrotal skin than clippers.

There may be little difference in length of hospital stay between participants who have hair removed with a razor versus those with no hair removal (low‐certainty evidence). It is uncertain whether there is a difference in cost when hair is removed with either a razor or with cream.

We identified no studies that compared clipping with depilatory cream, or that investigated the application of depilatory cream at different preoperative time points, or hair removal in different settings (e.g. ward, anaesthetic room).

Overall completeness and applicability of evidence

Surgical site infection was the primary outcome in 17 of the included studies and a secondary outcome in 8 included studies. The primary outcome in studies where SSI was a secondary outcome focused mainly on skin damage, patient preference, and adequacy of the hair removal. Most surgical specialty groups (except children) were represented in the included studies, and the studies were set in 12 different countries, therefore the results should apply to a wide range of people undergoing surgery.

Thirteen of the 25 included studies were published between 20 and 50 years ago, which will have an effect on the applicability of the findings of this review. Whilst the definition of a surgical site infection has not changed, many of the practices surrounding surgery, hair removal, and infections have changed. For example, the design and quality of razors, clippers, and depilatory cream have improved; antibiotic usage has changed greatly; the length of hospital stay has reduced, thereby affecting SSI surveillance and costs; pre‐hospital admissions have greatly reduced, affecting hair removal practices and costs; and orderlies who shaved patients in advance of surgery are no longer employed. Future updates and reviews may consider excluding trials over a specified age.

Very few studies explored treatment costs, and any exploration was very limited. As already mentioned, data from older studies regarding costs and length of stay may no longer be relevant.

Recent searches identified an increasing number of studies where hair removal protocols were part of a care bundle, though these studies were usually pre‐ and postintervention studies rather than RCTs. More recent studies seem more likely to use recognised definitions of SSIs with longer follow‐up periods.

The previous update of this review (Tanner 2011), which included studies where body hair or scalp hair was removed, suggested that clippers were associated with fewer SSIs than razors. Since that publication, the appropriateness of using clippers on scrotal hair has been questioned (Morey 2013), and studies have been carried out focusing on SSI and skin injury when using clippers or razors on male genitalia.

Quality of the evidence

We used the GRADE approach to assess all outcomes. For the primary outcome, surgical site infection, the certainty of evidence was assessed as moderate for five comparisons and low for one comparison. We downgraded the evidence for serious risk of bias (a substantial amount of data came QRCTs and were considered to be at high risk of bias), serious imprecision with wide confidence intervals, and very serious imprecision with a small sample size and wide confidence intervals. The certainty of evidence contributing to the secondary outcomes, wound complications, length of stay, and cost, was mainly assessed as low or very low, with one outcome rated as moderate certainty. In addition to serious risk of bias, serious imprecision due to either wide confidence intervals or small sample size, very serious imprecision due to small sample and wide confidence intervals, plus small sample size and small number of events, we considered studies of cost to have very serious indirectness, as only one aspect of treatment costs was included. We did not downgrade for inconsistency, as statistical heterogeneity was either not present or moderate. Three sensitivity analyses were conducted excluding QRCTs; the certainty of the evidence for all of these analyses was moderate due to serious imprecision (wide confidence intervals). The effect did not change in any of the sensitivity analyses.

The study setting and timing of hair removal relative to surgery were often poorly reported. Often the identity of the outcome assessor and the timing of assessment were not clear. Most of the trials provided information on the sex and age of study participants and the surgical procedure carried out, which permitted baseline comparisons.

Potential biases in the review process

We did not conduct funnel plots, as there were fewer than 10 studies in each comparison. All studies included in this review have been published in full, with the exception of Domes 2011, for which only an abstract has been published. We attempted to contact four study authors for additional information (Domes 2011; Ilankovan 1992; Lu 2002; Shi 2016), but these attempts were unsuccessful.

We identified 14 articles in languages other than English that required translation. Six of these studies were subsequently included in the review, and were published in Danish (Breiting 1981; Thorup 1985), French (Goëau‐Brissonnière 1987), Portuguese (Nascimento 1991), and Chinese (Lu 2002; Sun 2014). Only one potentially relevant study was identified through the clinical trials registries, and the findings from this study had already been published (Kowalski 2016). A systematic review, published in English by a researcher in China (Shi 2016), included four Chinese studies that were not identified through our search strategy (Li 2013; Liu 2008; Lu 2002; Sun 2014). We were able to obtain the full text for three of these studies (Liu 2008; Lu 2002; Sun 2014), and the abstract for the remaining study (Li 2013), and have these translated. Following translation, Lu 2002 and Sun 2014 were included in the review, and Li 2013 and Liu 2008 were excluded for not being randomised studies.

Agreements and disagreements with other studies or reviews

Implications for practice

Guidelines recommend that hair surrounding the operative site should not be routinely removed, and if hair has to be removed, then this should be done using clippers only in most cases (WHO 2018b). Review findings map to these recommendations, suggesting hair removal with a razor probably increases risk of SSI compared with no removal, and there may be little or no difference in SSI risk between no hair removal and use of clippers. Hair removal with razors probably increases the risk of SSI compared with clippers or cream. Regarding hair removal from male scrotal skin, very low‐certainty evidence means it is unclear whether razors or clippers cause more SSIs, but low‐certainty evidence suggests that razors may result in less trauma than clippers.

Implications for research

Comparison 1

Comparison 2

Comparison 3

Comparison 4

Comparison 5

Comparison 6

Characteristics of included studies [ordered by study ID]

Characteristics of excluded studies [ordered by study ID]

Characteristics of studies awaiting classification [ordered by study ID]

Contributions of editorial base

Nicky Cullum and Jo Dumville (Joint Co‐ordinating Editors): edited the previous and current versions of this review respectively, advised on methodology, interpretation, and review content. Jo Dumville approved this update prior to publication.

Sally Bell‐Syer (Managing Editor): co‐ordinated the editorial process for previous versions of this review and advised on methodology, interpretation and content.

Gill Rizzello (Managing Editor): co‐ordinated the editorial process for this update, advised on content and edited the update.

Ruth Foxlee, Reetu Child and Sophie Bishop (Information Specialists): designed the search strategy, ran the searches, and edited the search methods section for previous and current versions of this review.

Tom Patterson (Editorial Assistant): edited the reference sections for this update.

Internal sources

• De Montfort University, UK

• University of Nottingham, UK

External sources

• The National Institute for Health Research (NIHR), UK

  This project was supported by the National Institute for Health Research via Cochrane Infrastructure funding to Cochrane Wounds. The views expressed are those of the authors and not necessarily those of the NIHR or the Department of Health and Social Care.

• The Theatre Nurses' Trust Fund, UK

• The Association for Perioperative Practice, UK

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