Skin preparation for preventing infection following caesarean section

This review is an update of a review that was first published in 2012, and updated in 2014 and 2018.

What is the issue?
The aim of this Cochrane Review was to find out what methods of skin preparation before caesarean section were most effective in preventing infection after the operation. We collected and analysed all studies that assessed the effectiveness of antiseptics used to prepare the skin before making an incision (or cut) for the caesarean section. We only included analysis of preparations that were used to prepare the surgical site on the abdomen before caesarean section; we did not look at handwashing by the surgical team, or bathing the mother.

Why is this important?
Infections of surgical incisions are the third most frequently reported hospital-acquired infections. Women who give birth by caesarean section are exposed to infection from germs already present on the mother's own skin, or from external sources. The risk of infection following a caesarean section can be 10 times that of vaginal birth. Therefore, preventing infection by properly preparing the skin before the incision is made is an important part of the overall care given to women prior to caesarean birth. An antiseptic is a substance applied to remove bacteria that can cause harm to the mother or baby when they multiply. Antiseptics include iodine or povidone iodine, alcohol, chlorhexidine, and parachlorometaxylenol. They can be applied as liquids or powders, scrubs, paints, swabs, or on impregnated 'drapes' that stick to the skin, which the surgeon then cuts through. Non-impregnated drapes can also be applied, once the skin has been scrubbed or swabbed, with the aim of reducing the spread of any remaining bacteria during surgery. It is important to know if some of these antiseptics or methods work better than others.

What evidence did we find?
This updated review included 13 trials with 6938 women. Six trials were conducted in the USA; the remaining trials were in Nigeria, South Africa, France, Denmark, Indonesia, India and Egypt. The review looked at what was best for women and babies when it came to important outcomes including: infection of the site where the surgeon cut the woman to perform the caesarean section; inflammation of the lining of the womb (metritis and endometritis); how long the woman stayed in hospital; and any other adverse effects, such as irritation of the woman's skin, or any reported impact on the baby. Not all of the 13 trials explored all of these outcomes, and the evidence for each outcome was usually based on results from far fewer than 6938 women.

Much of the evidence we found was of relatively poor quality, due to limits in the ways that the studies were conducted. This means that we could not be certain about most of the findings. The evidence suggested that in women who had their skin prepared using the agent chlorhexidine gluconate, there is probably a slight reduction in the incidence of surgical site infection compared to women who had their skin prepared using povidone iodine. For other outcomes there was little or no difference between the various antiseptic agents and methods of application in terms of endometritis, skin irritation, or allergic skin reaction in the mother. In one study, there was a reduction in bacterial growth on the skin at 18 hours after caesarean section for women who received a skin preparation with chlorhexidine gluconate compared with women who received the skin preparation with povidone iodine, but more data are needed to see if this actually reduces infections for women.

What does this mean?
The available evidence from the trials that have been conducted was insufficient to tell us the best type of skin preparation for preventing surgical site infection following caesarean section. More high-quality research is needed. We found two studies that are still ongoing. We will incorporate the results of these studies into this review in future updates.

Authors' conclusions: 

Moderate-certainty evidence suggests that preparing the skin with chlorhexidine gluconate before caesarean section is probably slightly more effective at reducing the incidence of surgical site infection in comparison to povidone iodine. For other outcomes examined there was insufficient evidence available from the included RCTs. Most of the evidence in this review was deemed to be very low or low certainty. This means that for most findings, our confidence in any evidence of an intervention effect is limited, and indicates the need for more high-quality research. Therefore, it is not yet clear what sort of skin preparation may be most effective for preventing postcaesarean surgical site infection, or for reducing other undesirable outcomes for mother and baby.

Well-designed RCTs, with larger sample sizes are needed. High-priority questions include comparing types of antiseptic (especially iodine versus chlorhexidine), and application methods (scrubbing, swabbing, or draping). We found two studies that are ongoing; we will incorporate the results of these studies in future updates of this review.

Read the full abstract...
Background: 

The risk of maternal mortality and morbidity is higher after caesarean section than for vaginal birth. With increasing rates of caesarean section, it is important to minimise risks to the mother as much as possible. This review focused on different skin preparations to prevent infection. This is an update of a review last published in 2018.

Objectives: 

To compare the effects of different antiseptic agents, different methods of application, or different forms of antiseptic used for preoperative skin preparation for preventing postcaesarean infection.

Search strategy: 

For this update, we searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP) (9 July 2019), and reference lists of retrieved studies.

Selection criteria: 

Randomised and quasi-randomised trials, evaluating any type of preoperative skin preparation (agents, methods or forms). We included studies presented only as abstracts, if there was enough information to assess risk of bias.

Comparisons of interest in this review were between: different antiseptic agents (e.g. alcohol, povidone iodine), different methods of antiseptic application (e.g. scrub, paint, drape), different forms of antiseptic (e.g. powder, liquid), and also between different packages of skin preparation including a mix of agents and methods, such as a plastic incisional drape, which may or may not be impregnated with antiseptic agents. We mainly focused on the comparison between different agents, with and without the use of drapes.

Only studies involving the preparation of the incision area were included. This review did not cover studies of preoperative handwashing by the surgical team or preoperative bathing.

Data collection and analysis: 

Three review authors independently assessed all potential studies for inclusion, assessed risk of bias, extracted the data and checked data for accuracy. We assessed the certainty of the evidence using the GRADE approach.

Main results: 

We included 13 individually-randomised controlled trials (RCTs), with a total of 6938 women who were undergoing caesarean section. Twelve trials (6916 women) contributed data to this review. The trial dates ranged from 1983 to 2016. Six trials were conducted in the USA, and the remainder in India, Egypt, Nigeria, South Africa, France, Denmark, and Indonesia.

The included studies were broadly at low risk of bias for most domains, although high risk of detection bias raised some specific concerns in a number of studies. Length of stay was only reported in one comparison.

Antiseptic agents

Parachlorometaxylenol with iodine versus iodine alone

We are uncertain whether parachlorometaxylenol with iodine made any difference to the incidence of surgical site infection (risk ratio (RR) 0.33, 95% confidence interval (CI) 0.04 to 2.99; 1 trial, 50 women), or endometritis (RR 0.88, 95% CI 0.56 to 1.38; 1 trial, 50 women) when compared with iodine alone, because the certainty of the evidence was very low. Adverse events (maternal or neonatal) were not reported.

Chlorhexidine gluconate versus povidone iodine

Moderate-certainty evidence suggested that chlorhexidine gluconate, when compared with povidone iodine, probably slightly reduces the incidence of surgical site infection (RR 0.72, 95% CI 0.58 to 0.91; 8 trials, 4323 women). This effect was still present in a sensitivity analysis after removing four trials at high risk of bias for outcome assessment (RR 0.87, 95% CI 0.62 to 1.23; 4 trials, 2037 women).

Low-certainty evidence indicated that chlorhexidine gluconate, when compared with povidone iodine, may make little or no difference to the incidence of endometritis (RR 0.95, 95% CI 0.49 to 1.86; 3 trials, 2484 women). It is uncertain whether chlorhexidine gluconate reduces maternal skin irritation or allergic skin reaction (RR 0.64, 95% CI 0.28 to 1.46; 3 trials, 1926 women; very low certainty evidence).

One small study (60 women) reported reduced bacterial growth at 18 hours after caesarean section for women who had chlorhexidine gluconate preparation compared with women who had povidone iodine preparation (RR 0.23, 95% CI 0.07 to 0.70).

Methods

Drape versus no drape

This comparison investigated the use of drape versus no drape, following preparation of the skin with antiseptics.

Low-certainty evidence suggested that using a drape before surgery compared with no drape, may make little or no difference to the incidence of surgical site infection (RR 1.29, 95% confidence interval (CI) 0.97 to 1.71; 3 trials, 1373 women), and probably makes little or no difference to the length of stay in the hospital (mean difference (MD) 0.10 days, 95% CI -0.27 to 0.46; 1 trial, 603 women; moderate-certainty evidence). One trial compared an alcohol scrub and iodophor drape with a five-minute iodophor scrub only, and reported no surgical site infection in either group (79 women, very-low certainty evidence). We were uncertain whether the combination of a one-minute alcohol scrub and a drape reduced the incidence of metritis when compared with a five-minute scrub, because the certainty of the evidence was very low (RR 1.62, 95% CI 0.29 to 9.16; 1 trial, 79 women). The studies did not report on adverse events (maternal or neonatal).

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