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.

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 swapped, 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 11 trials with 6237 women. Six trials were conducted in the United States; the remaining trials were in Nigeria, South Africa, France, Denmark, and Indonesia. 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 11 trials explored all of these outcomes, and the evidence for each outcome was usually based on results from far fewer than 6237 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, even when we combined the results from a number of different studies. The evidence suggested that there was probably little or no difference between the various antiseptics in the incidence of surgical site infection, endometritis, skin irritation, or allergic skin reaction in the mother. However, 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 four studies that were still ongoing. We will incorporate the results of these studies into this review in future updates.

Authors' conclusions: 

There was insufficient evidence available from the included RCTs to fully evaluate different agents and methods of skin preparation for preventing infection following caesarean section. 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.

Most of the evidence in this review was deemed to be very low or low quality. 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.

This field needs high quality, well designed RCTs, with larger sample sizes. High priority questions include comparing types of antiseptic (especially iodine versus chlorhexidine), and application methods (scrubbing, swabbing, or draping). We found four studies that were 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 (particularly postoperative infection) is higher for caesarean section (CS) than for vaginal birth. With the increasing rate of CS, it is important to minimise the risks to the mother as much as possible. This review focused on different forms and methods of preoperative skin preparation to prevent infection. This review is an update of a review that was first published in 2012, and updated in 2014.

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) (27 November 2017), and reference lists of retrieved studies.

Selection criteria: 

Randomised and quasi-randomised trials, evaluating any type of preoperative skin preparation agents, forms, and methods of application for caesarean section.

Comparisons of interest in this review were between different antiseptic agents used for CS skin preparation (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 skin preparations, such as a plastic incisional drape, which may or may not be impregnated with antiseptic agents.

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, and extracted the data using a predesigned form. We checked data for accuracy. We assessed the quality of the evidence using the GRADE approach.

Main results: 

For this update, we included 11 randomised controlled trials (RCTs), with a total of 6237 women who were undergoing CS. Ten trials (6215 women) contributed data to this review. All included studies were individual RCTs. We did not identify any quasi- or cluster-RCTs. The trial dates ranged from 1983 to 2016. Six trials were conducted in the USA, and the remainder in Nigeria, South Africa, France, Denmark, and Indonesia.

The included studies were broadly methodologically sound, but raised some specific concerns regarding risk of bias in a number of cases.

Drape versus no drape

This comparison investigated the use of a non-impregnated drape versus no drape, following preparation of the skin with antiseptics. For women undergoing CS, low-quality 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 (risk ratio (RR) 1.29, 95% confidence interval (CI) 0.97 to 1.71; 2 trials, 1294 women), or length of stay in the hospital (mean difference (MD) 0.10 day, 95% CI -0.27 to 0.46 1 trial, 603 women).

One-minute alcohol scrub with iodophor drape versus five-minute iodophor scrub without drape

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 quality evidence). We were uncertain whether the combination of a one-minute alcohol scrub and a drape reduced the incidence of endomyometritis when compared with a five-minute scrub, because the quality of the evidence was very low (RR 1.62, 95% CI 0.29 to 9.16; 1 trial, 79 women).

Parachlorometaxylenol with iodine versus iodine alone

We were uncertain whether parachlorometaxylenol with iodine before CS made any difference to the incidence of surgical site infection (RR 0.33, 95% 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 quality of the evidence was very low.

Chlorhexidine gluconate versus povidone iodine

Low-quality evidence suggested that chlorhexidine gluconate before CS, when compared with povidone iodine, may make little or no difference to the incidence of surgical site infection (RR 0.80, 95% CI 0.62 to 1.02; 6 trials, 3607 women). However, surgical site infection appeared to be slightly reduced for women for whom chlorhexidine gluconate was used compared with povidone iodine after we removed four trials at high risk of bias for outcome assessment, in a sensitivity analysis (RR 0.59, 95% CI 0.37 to 0.95; 2 trials, 1321 women).

Low-quality evidence indicated that chlorhexidine gluconate before CS, when compared with povidone iodine, may make little or no difference to the incidence of endometritis (RR 1.01, 95% CI 0.51 to 2.01; 2 trials, 2079 women), or to reducing maternal skin irritation or allergic skin reaction (RR 0.60, 95% CI 0.22 to 1.63; 2 trials, 1521 women).

One small study (60 women) reported reduced bacterial growth at 18 hours after CS 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).

None of the included trials reported on maternal mortality or repeat surgery.

Chlorhexidine 0.5% versus 70% alcohol plus drape

One trial, which was only available as an abstract, investigated the effect of skin preparation on neonatal adverse events, and found cord blood iodine concentration to be higher in the iodine group.

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