Headwear options for operating room staff to prevent surgical infection: a systematic review and meta-analysis of the evidence
GJ Williams, D Salim, SM Collins, JF ThompsonBackground:
A recommendation was made in 2015 that, for surgical procedures, staff should completely cover their hair and ears. Much debate ensued, highlighting the scant evidence that the type of head covering affected surgical infection rates.
Methods:
MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials were searched up to 3 June 2025, and a registered systematic review was undertaken. Included studies were those that compared two or more different head coverings for staff involved in surgical procedures and reported infection rates. Forest plots were generated; random-effects models were used for all analyses, and fixed-effects models were used for risks generated from multivariable analyses. Risk-of-bias assessments used the Cochrane tool for randomized controlled trials (RCTs) and the Newcastle–Ottawa Scale for non-randomized studies.
Results:
From 203 unique titles, 12 studies that compared outcomes for different head-covering options were identified. Two RCTs reported estimates of the risk of surgical infection with caps compared to no head covering, and in neither was there a statistically-significant difference, but both trials were underpowered for the outcome of interest. Four studies with a study design comparing a before-versus-after head-covering policy used multivariable analyses that adjusted for other important factors. Pooled analysis showed no difference in the infection risk before and after policy implementation [odds ratio 1.06, 95% confidence interval 0.85–1.32,
Conclusions:
Current evidence does not show that any specific form of head covering is superior to another, nor indeed to no head covering. Existing policies that restrict head-covering choice to reduce surgical infection were based on limited, low-certainty evidence, and the present evidence update does not support a restrictive policy.