best practice perioperative strategies and surgical techniques ...73 surgical site infection (ssi)...
TRANSCRIPT
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Title Page 1
Manuscript title: 2
Best practice perioperative strategies and surgical techniques for preventing 3
caesarean section surgical site infections: a systematic review. 4
5
Authors: 6
Elizabeth K MARTIN (M Hlth Econ)1 7
Michael M BECKMANN (MBBS FRANZCOG)2 8
Louise N BARNSBEE (B Hlth Sci)1 9
Kate A HALTON (PhD)1 10
Katharina M D MEROLLINI (PhD)3 11
Nicholas GRAVES (PhD)1 12
13
1Institute of Health and Biomedical Innovation, Queensland University of 14
Technology, Brisbane, Queensland, Australia 15
2Mater Health Services, Brisbane, Queensland, Australia 16
3Faculty of Science, Health, Education and Engineering, University of the Sunshine 17
Coast, Maroochydore, Queensland, Australia 18
19
Corresponding author: 20
Elizabeth Martin 21
School of Public Health and Social Work, Queensland University of Technology 22
60 Musk Ave, Kelvin Grove, Qld, Australia, 4059 23
+61 731386119 24
+61 422809021 25
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Abstract word count: 226 28
Main text word count: 2976 29
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Shortened running title: Preventing caesarean SSIs. 31
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Abstract 32
Background: Surgical site infection (SSI) following caesarean section is a problem 33
for women and health services. Caesarean section is a high volume procedure and 34
the estimated incidence of SSI may be as high as 9%. 35
Objectives: The objective of this study was to identify a suite of perioperative 36
strategies and surgical techniques that reduce the risk of SSI following caesarean 37
section. 38
Search strategy: 39
Six electronic databases were searched to systematically review literature reviews, 40
systematic reviews and meta-analyses published from 2006 to 2016. Search terms 41
included: endometritis, SSI, caesarean section, meta-analysis, review, systematic. 42
Selection criteria: Studies were sought in which competing perioperative strategies 43
and surgical techniques relevant for caesarean section were identified and 44
quantifiable infection outcomes were reported. General surgical infection control 45
techniques were excluded. 46
Data collection and analysis: Data on study characteristics and clinical effectiveness 47
were extracted. Quality, including bias within individual studies, was examined using 48
a modified A Measurement Tool to Assess Systematic Reviews (AMSTAR) checklist. 49
Recommendations for SSI risk reducing strategies were developed using the 50
Grading of Recommendations Assessment, Development and Evaluation (GRADE) 51
approach. 52
Main results: Of 466 records retrieved, 44 studies were selected for the evidence 53
synthesis. Recommended strategies were: administer pre-incision antibiotic 54
prophylaxis, prepare the vagina with iodine-povidone solution and spontaneous 55
placenta removal. 56
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Conclusions: We recommend clinicians implement pre-incision antibiotic prophylaxis, 57
vaginal preparation and spontaneous placenta removal as an infection control 58
bundle for caesarean section. 59
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Tweetable abstract: Infection control for caesarean: pre-incision AB prophylaxis, 61
vaginal prep, spontaneous placenta removal. 62
63
Key words: 64
Best practice 65
Caesarean section 66
Clinical guidelines 67
Evidence synthesis 68
SSI 69
Systematic review 70
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Introduction 72
Surgical site infection (SSI) following caesarean section is a problem for women and 73
health services. Infection rates vary between 4.9% and 9.8%.1-3 The consequences 74
of SSI following caesarean section for women include pain and delay returning to 75
normal activities,4 chronic pelvic pain,5 persistent seroma,6 and depression,7 as well 76
as out of pocket costs.8, 9 Costs for a health system include additional staff time, use 77
of pharmaceutical and healthcare supplies, and increased length of stay or re-78
admission to hospital – potentially occupying a hospital bed that could be used by 79
another.10 80
81
Evidence for perioperative strategies and surgical techniques has not been 82
adequately synthesised for nurses and physicians (hereafter referred to as 83
‘clinicians’) and may not always be accessible, as evidenced by large variation in 84
practice.11-13 Available evidence mostly reports effectiveness of individual risk 85
reducing strategies, which means up-to-date evidence for all potential strategies is 86
not available in a single document. Furthermore, SSI is not always a primary 87
outcome and publications need to be read in depth to identify the impact of each 88
strategy on SSI. A systematic review published in 2013 that examined a range of 89
interventions14 quickly became outdated due to new evidence.6, 15-26 In a more recent 90
systematic review27 the authors did not make clear recommendations for clinical 91
practice, while the quality of a third review28 is questionable because its methods are 92
not clear. 93
94
A transparent and structured synthesis of systematic reviews, meta-analyses and 95
other types of reviews has value in informing clinical decision makers of best practice 96
6
and remaining gaps.29, 30 The large number of caesarean section review studies on 97
individual strategies and techniques are difficult for decision makers to decipher. 98
Evidence syntheses cut through the wealth of evidence while assessing consistency 99
and quality, and providing definitive summaries to inform clinical practice.29, 30 100
Cochrane Collaboration acknowledged that this is the case and introduced evidence 101
synthesis methods in their handbook.31 102
103
The objective of this study was to identify a suite of perioperative strategies and 104
surgical techniques that reduce SSI risk following caesarean section. This paper will 105
be helpful for clinical teams who seek guidance on reducing the risk of SSI following 106
caesarean section, as the information is presented with the needs of clinical decision 107
makers in mind. Making evidence-informed infection prevention decisions when 108
caring for women having a caesarean section will reduce excess healthcare costs 109
and improve maternal quality of life. 110
111
Methods 112
A systematic review of literature reviews, systematic reviews and meta-analyses was 113
conducted using the PRISMA guidelines32 to identify the most effective perioperative 114
strategies and surgical techniques for reducing the risk of SSI following caesarean 115
section. A protocol is available33 and the review registered with Prospero (number 116
CRD42016041366).34 The study was exempt from Institutional Review Board 117
approval because the research was not conducted with humans or animals and used 118
publically available data. 119
120
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Two researchers (EM and LB) independently searched electronic databases 121
PubMed, CINAHL, Cochrane Library, Science Direct, Scopus and Embase for review 122
studies published in the English language between January 2006 and June 2016. 123
Only review studies were chosen, and no clinical trials, as this study seeks to 124
synthesise the key strategies with as large a volume of effectiveness evidence as 125
possible. The 10-year timeframe corresponds to the extensive research activity that 126
commenced after the rate of caesarean sections began to increase in the late 1990s. 127
128
The search strategy sought studies that synthesised SSI outcomes for women who 129
had an emergency or elective caesarean section and were any age, parity and risk 130
category. Any type of perioperative or surgical intervention and appropriate 131
comparator relevant to caesarean section was of interest. The primary outcome was 132
SSI, defined according to the US Centers for Disease Control and Prevention (CDC) 133
classifications of superficial or deep incisional and organ/space infection, including 134
endometritis.35 The term ‘wound infection’ was accepted as an alternative outcome 135
description but aggregate measures of infection such as “total infectious morbidity” 136
was not used. Caesarean section wound infection is part of the recommended 137
maternity care core outcomes set within the CROWN initiative.36 S1 shows the 138
PubMed search strategy for this review that can be replicated to verify or update the 139
results. 140
141
This systematic review is specifically designed to inform providers of maternity care 142
rather than broader hospital practice. The evidence has already been established for 143
the importance of infection prevention strategies common to most surgeries at a 144
general healthcare and surgical healthcare level such as hand hygiene, hemostasis 145
8
and antibiotic prophylaxis but – importantly – not the timing of prophylaxis. As such, 146
inclusion and exclusion criteria were developed to reflect the focus of this review and 147
shown in Table 1. Titles, then abstracts, were independently scanned and full text 148
studies were retrieved if the inclusion/exclusion criteria were met. 149
150
Insert Table 1 151
152
Data was extracted and bias within each review assessed independently by two 153
researchers (EM and LB). Data identifying the review, key study characteristics and 154
effectiveness of perioperative strategies and surgical techniques on SSI (usually 155
relative risk as the summary measure) were entered into a data extraction template. 156
Bias was examined using a modified A Measurement Tool to Assess Systematic 157
Reviews (AMSTAR) checklist and categorisation method developed by McKibben 158
and colleagues.27 The quality of individual studies was reported as ‘good’, ‘fair’ or 159
‘poor’ using the McKibben method.27 To qualify as a ‘good’ quality study, two or more 160
of the four major criteria must have been met, as well as four or more of the 23 minor 161
assessment quality criteria. The method for assigning a quality rank to individual 162
studies is summarised in Table 2 and we direct readers to the original paper for more 163
detail.27 164
165
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Insert Table 2 166
167
A list of perioperative strategies and surgical techniques, and their effectiveness in 168
reducing SSI risk, was created. Recommendations were made for each strategy 169
using the GRADE approach of assessing the four determinants of the strength of a 170
recommendation: effect; quality of evidence; value and preferences; and costs.37 171
Effectiveness data from the most recent ‘good’ quality studies were examined to 172
avoid overstating the strength of the recommendation for each strategy however, the 173
effect size was checked against other studies for consistency. This meant 174
randomised controlled trials included in multiple meta-analyses were not counted 175
twice, but important and relevant evidence was still captured. Quality of evidence as 176
determined by the original authors of the most recent good quality study selected for 177
each strategy or surgical technique in this synthesis, was used to inform the strength 178
of each recommendation. A suite of infection control strategies was chosen from 179
those with strong recommendations and the highest evidence quality. 180
181
Other adverse outcomes reported in the included studies such as blood loss, 182
unintended uterine extensions and including wasted health service resources were 183
noted in the data extraction process. It was important to identify strategies that had 184
potential maternal or perinatal morbidity despite their effectiveness in reducing 185
infection risk. The relative importance of non-infection outcomes was considered 186
against infection outcomes when developing the suite of infection control strategies. 187
188
A health consumer representative from the organisation Maternity Choices, was 189
involved in the interpretation of the findings as part of their contribution to the 190
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broader research that this study is part of. The health consumer commented on the 191
appropriateness of the results and the focus of the research on the maternal, rather 192
than infant, perspective 193
194
Funding for this study was provided by the Centre of Research Excellence in 195
Reducing Healthcare Associated Infections. This was not an awarded grant and did 196
not include an external peer review for scientific quality. The Centre of Research 197
Excellence had no role in conducting the research or writing the paper. 198
199
Results 200
In the systematic review and development of the suite of infection control strategies, 201
67 full text studies were assessed for eligibility. From these, 44 studies were 202
included for data extraction and synthesis (see Figure 1). Thirty-two studies were 203
meta-analyses, one was a systematic review and 11 were non-systematic literature 204
reviews. Excluded studies following abstract screening and full-text assessment for 205
eligibility with reasons are in S2. 206
207
Insert Figure 1. 208
209
Amongst the systematic reviews and meta-analyses, 33 were categorised as good 210
quality and one study was given a ‘fair’ quality rating (see S3). The ‘fair’ quality study 211
only met one of the four major quality assessment criteria and did not conduct 212
duplicate data extraction, only searched one database and did not rate and 213
document the quality of included studies. Non-systematic reviews were all assessed 214
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as ‘poor’ quality as they did not provide enough information on the criteria required in 215
the McKibben assessment method.27 216
217
Seventeen different types of perioperative strategies and surgical techniques for 218
caesarean section were identified as having been evaluated for their effectiveness in 219
reducing the risk of SSI (see Table 3). The groups of strategies with the largest 220
number of studies assessing effectiveness were antibiotic prophylaxis and skin 221
closure. 222
223
Insert Table 3 224
225
There was much variation regarding the specific interventions and comparators 226
examined within each type of strategy. Seventeen studies evaluated three different 227
aspects of antibiotic prophylaxis: timing, antibiotic class and route of administration. 228
The effectiveness of 22 different combinations of antibiotic classes was reported 229
across one meta-analysis23 and one systematic review.38 Similarly, multiple 230
intervention comparator pairs were also evaluated for skin incision, uterine closure, 231
peritoneum closure, wound drainage and skin closure (see S4). In total, 82 232
intervention comparator pairs were identified in this study as having been evaluated 233
for their effectiveness in reducing the risk of caesarean section SSI. All included 234
studies that informed the list of perioperative strategies and surgical techniques are 235
provided in Table 3, while the single most recent good quality studies that influenced 236
the recommendations are in the text below. 237
238
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The effectiveness of the 82 intervention comparator pairs was examined. From 239
these, three perioperative strategies and surgical techniques with strong evidence for 240
reducing the risk of SSI following caesarean section were identified for the suite of 241
infection control strategies. The strategies were: administer prophylactic antibiotics 242
15 to 60 minutes before incision; prepare the vagina with iodine-povidone solution; 243
and remove the placenta spontaneously with gentle cord traction (see Table 3). Pre-244
incision antibiotic prophylaxis reduced the risk of endometritis by 46% and wound 245
infection by 41%.20 Vaginal preparation reduced the risk of endometritis by 55%, but 246
did not have an effect on wound infection.6 The risk of endometritis was increased by 247
64% with manual removal of the placenta.39 The three strategies had clear evidence 248
of reducing the risk of caesarean section SSI and the associated recommendations 249
were all strong based on an assessment of the four determinants of recommendation 250
strength used in the GRADE approach (see Table 3). 251
252
Two strategies received strong recommendations for providing other surgical 253
benefits despite little evidence for their effect in reducing SSI risk (see Table 3). 254
Significantly fewer unintended uterine extensions and a trend towards less blood 255
loss was observed with blunt cephalad-caudad uterine expansion.21 Closing the skin 256
with subcuticular sutures has a significantly lower risk of wound complication such as 257
wound dehiscence.18 258
259
Three strategies were strongly not recommended for implementation, because of the 260
potential to waste scarce healthcare resources (see Table 3). Supplemental 261
oxygen,40 mechanical dilatation of the cervix,41 and using a subcutaneous drain 262
(even in obese women or women with subcutaneous tissue greater than 2cm)42 263
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resulted in no beneficial health outcomes and unnecessarily lengthened surgery time 264
occupying theatres that could be freed for another use. 265
266
Intra-abdominal irrigation received a strong recommendation to not implement 267
because no additional health benefit was reported and it is significantly associated 268
with intraoperative nausea (see Table 3).17 269
270
Discussion 271
Main Findings 272
Three perioperative caesarean section strategies and surgical techniques to reduce 273
SSI risk have been identified as having strong evidence for universal 274
implementation: pre-incision antibiotic prophylaxis, vaginal preparation with an 275
iodine-povidone solution and spontaneous placenta removal. We recommend these 276
strategies to clinicians as an infection control bundle that should be trialled in 277
practice. This infection control bundle meets the Institute for Healthcare 278
Improvement definition43 as it consists of three evidence-based interventions 279
specifically for caesarean section, and we hypothesise that when implemented 280
together, the bundle will reduce SSI risk more than adhoc implementation of the 281
individual elements. 282
283
Strengths 284
The strength of this study is that a rigorous synthesis of all caesarean section 285
perioperative strategies and surgical techniques that have been examined for their 286
impact on SSI has been conducted. The GRADE approach used, infection control 287
bundle developed and additional recommendations have resulted clearly outlined 288
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best practice guidelines for clinicians. We did not assess evidence quality in this 289
study, but extracted original authors’ assessments of evidence quality and used the 290
data to inform the strength of recommendations made. By examing the four factors 291
that determine the strength of a GRADE recommendation: effects, quality of 292
evidence, values and preferences, and costs, we offer clinical practice guidance that 293
a systematic review alone can not provide. 294
295
The focus on infection prevention opportunities perioperatively and during surgery at 296
caesarean section is a unique aspect of this study. Alternative foci for identifying SSI 297
risk reducing strategies were general surgical or healthcare approaches; or 298
addressing intrinsic patient-related risk factors. However the evidence for general 299
infection control strategies to prevent healthcare associated infections is well 300
established, and addressing risk factors instrisic to the patient was beyond the scope 301
this study. Clinicians mostly understand risk factors for SSI that are intrinsic to the 302
patient, but variation in caesarean section techniques11-13 suggests there is more 303
uncertainty regarding best practice from a perioperative and surgical perspective. 304
305
Limitations 306
In this study, we synthesised evidence from reviews, systematic reviews and meta-307
analyses given the prominence placed on the type of evidence generated by the 308
latter two for clinical end users. As such, a limitation is that there may be strategies 309
that have been trialled and demonstrate an effect in reducing SSI risk such as 310
chlorhexidine-gluconate for skin preparation,44 but not captured in this study because 311
the small volume of evidence has not warranted a review by other researchers. A 312
synthesis of reviews, systematic reviews and meta-analyses is not an appropriate 313
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method for the development of a full clinicial guideline for caesarean section. There 314
is potential for bias in this approach if other researchers were unable to publish or 315
have not conducted systematic reviews of strategies and techniques that may 316
reduce SSI risk and further inform this study. We have not attempted to write an 317
authoritative source for all recommended practice at caesarean section, but provide 318
a targetted suite of infection control strategies that are potentially under utilised 319
despite the evidence for their effectiveness. 320
321
An additional limitation is that the infection control bundle has not been trialled in 322
practice. Our recommendation to clinicians that the bundle be implemented for every 323
caesarean section is based on an hypothesis that the evidence for each individual 324
strategy is strong and, when consistently implemented together, infection outcomes 325
would improve further. However, it is not clear what the relative contribution optimal 326
perioperative and surgical technique has to overall healthcare associated infection 327
prevention measures. Perhaps in practice, the infection control bundle will have little 328
impact while general surgical infection control practices are substandard and/or risk 329
factors intrinsic to the patient remain present. A study that evaluates the infection 330
control bundle while measuring general infection control practice and intrinsic risk 331
factors is needed. 332
333
The primary outcome for this study was maternal SSI, and long term infant outcomes 334
were not considered. This limitation is relevant for the recommendation to administer 335
prophylactic antibiotics before skin incision rather than post-cord clamping because 336
the infant is potentially exposed to antibiotics with pre-incision administration. While 337
there is no evidence of masked neonatal sepsis in the short term,20 there is emerging 338
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evidence of an infant gut microbiota imbalance45 and little understanding of the long-339
term outcomes such as development of chronic disease following fetal exposure to 340
antibiotics.46 341
342
There is a noteable limitation to the recommendation favouring one-layer uterine 343
closure as two-layer closure is considered by many obstetricians to be associated 344
with a lower risk of uterine rupture in subsequent pregnancies. The conflicting results 345
regarding risk of uterine rupture between the randomised controlled trials analysed 346
by the two studies included in our systematic review24, 47 and good quality 347
observational studies48, 49 are an important issue to resolve with further research. 348
One-layer uterine closure has no apparent effect on SSI and its only benefit is a 349
shorter duration of surgery by six minutes.47 With other evidence raising concerns 350
about one-layer uterine closure, we cannot make a strong recommendation for this 351
technique. 352
353
Interpretation 354
The results of this study are generally paralleled in other studies. We identified 82 355
perioperative strategies and surgical techniques that have been evaluated for their 356
impact on reducing SSI risk, while 77 strategies were found in the McKibben study.27 357
There was agreement between ours and the McKibben study for 17 out of 18 quality 358
ratings given to each of the included studies using the modfied AMSTAR method.27 359
The strategies recommended in this paper also align with some of those identified in 360
the McKibben paper.27 However, we disagree that the Joel-Cohen skin incision and 361
that suturing thick (≥ 2cm) subcutaneous tissue is definitively superior to their 362
alternatives in reducing SSI risk. For skin incision,50 we examined outcomes for 363
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wound infection only, and it appears McKibben used a broader infection outcome.27 364
For suturing of subcutaneous tissue, we selected an updated study for inclusion42 365
which was different to that used by McKibben.27 Updated evidence for vaginal 366
preparation has been sythesied in this study, allowing a stronger recommendation to 367
be made since a study by Dahlke and colleagues was published.14 However as the 368
quality of evidence included in a meta-analysis selected for our study was assessed 369
as low,6 more research for vaginal preparation is warranted, particulary as the effect 370
sizes may not be seen across all sub-populations. Our results otherwise corroborate 371
with the Dahlke study. 372
373
Conclusion 374
A perioperative and surgical infection control bundle specifically for caesarean 375
section has been developed through a comprehensive synthesis of the key 376
evidence. The infection control bundle is: pre-incision administration of prophylactic 377
antibiotics, vaginal preparation with iodine-povidone solution and spontaneous 378
removal of the placenta. 379
380
381
Disclosure statement: 382
The authors report no conflict of interest. 383
384
Author Contributions: 385
EM conceived the study, NG, MB, KH and KM guided the planning of the study with 386
EM, EM and LB collected the data and EM analysed the results. The manuscript was 387
prepared by EM with assistance from LB, NG, MB, KH and KM. 388
389
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Ethics details: 390
Prospero (number CRD42016041366).34 The study was exempt from Institutional 391
Review Board approval because the research was not conducted with humans or 392
animals and used publically available data. 393
394
Funding: 395
Funding for Louise Barnsbee’s salary to conduct duplicate searching, quality 396
assessment and data extraction was provided by the Centre of Research Excellence 397
in Reducing Healthcare Associated Infections. The Centre of Research Excellence 398
had no involvement in the study design, collection, analysis and interpretation of 399
data, writing of the report and the decision to submit the article for publication. 400
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