Laparotomy Wound Edge Protection Not an Effective Barrier to
Prevent Surgical Site Infection
Noman Shahzad*, Khwaja Muhammad Inam Pal and Hasnain Zafar
Department of General Surgery, Aga Khan University Hospital Karachi, Pakistan
Received date: 16 Aug 2017; Accepted date: 09 Nov 2017; Published
date: 15 Nov 2017.
*Corresponding author: Noman Shahzad, Department of General
Surgery, Aga Khan University Hospital Karachi, Pakistan, Tel:
Introduction: Surgical site infections (SSIs) after abdominal surgery are important cause of morbidity and even mortality. These are known to have social as well as economic impact upon individuals and society at large. Pathogens from gastrointestinal tract are responsible for
majority of surgical site infections after laparotomy. So wound edge protection from these organisms during surgery can potentially reduce
incidence of SSIs. Several previous studies have investigated the effect of wound edge protectors on SSI rates in abdominal surgery and
reported mixed results.
Objective: To measure frequency of Surgical Site Infections in patients who underwent laparotomy wound edge protection by plastic sheet.
Methods: We conducted single arm prospective cohort study, in which modified polyethylene wound protector was used to protect wound
during surgery. It is improvised form of commercially available wound protectors. Wound infection was assessed according to centre for
disease control criteria within 30 days of surgery. Results were compared with reported rates from same institution.
Results: We recruited 76 patients for inclusion in the study. Seven of these patients (9.2%) developed surgical site infections. Three had
superficial surgical site infections while four had deep surgical site infections. There was no statistically significant difference in infection rate
from our data as compared to reported rate of 6.7% (p=.81). After adjusting for all predictor variables, degree of intra-operative contamination
was the only independent predictor of acquiring surgical site infection.
Conclusion: Our study failed to show any benefit of wound edge protection. Randomized trial is recommended to consolidate the evidence.
Keywords: Surgical Site Infection; Wound Protector; Laparotomy
Surgical site infections (SSIs) are one of the most common causes of
Hospital Acquired Infections and are responsible for significant economic
burden . They account for considerable morbidity for the patients in
terms of increased length of hospital stay, organ dysfunction and even
mortality. On average SSIs increase hospital stay by 3 to 9.7 days and cost
of care up to 30000 dollars per admission [2,3]. It is also associated with
indirect cost in the form of abstinence from work and mental and social
disturbance. In its guidelines to prevent SSIs, Centre for Disease Control
and Prevention (CDC) has developed standardized criteria for defining
and classifying SSIs . According to these definitions SSIs have been
divided into superficial incisional SSI, deep incisional SSI and organ/space
SSI. Incidence of SSIs after open abdominal surgeries remains high despite
adequate aseptic and antiseptic measures. It ranges from 0.5% in clean
surgeries  to up to 32.1% in contaminated or emergency surgeries .
Micro-organisms from gastrointestinal tract are responsible for
majority of surgical site infections after laparotomy , thereby wound
edge protection from these organisms during surgery can potentially
reduce incidence of SSIs. Several studies have been conducted to
investigate the effect of application of plastic wound edge protection
devices during laparotomy on rate of surgical site infection with varying
results. Some of those studies failed to show additional benefit [8,9], while
on the other hand significant reduction in SSI has been reported by other
authors [10,11]. A recent meta-analysis comprising sixteen randomized
controlled trials witnessed a significant reduction in surgical site infection
after wound edge protection .
Commercially available devices to provide mechanical barrier to
physical contact of intra-abdominal contents with laparotomy wound
are costly and not available to every healthcare set up. An improvised
way of protecting wound could be covering it with sterile plastic sheet.
Though all available literature regarding outcome of wound protection
has come from studies using these commercially available products, data
on improvised methodology is lacking. So we planned to conduct this
study to look at change in risk of laparotomy wound infection if wound is
protected through sterile plastic sheet.
To measure frequency of Surgical Site Infections in patients who
underwent laparotomy wound edge protection by plastic sheet.
Material and Methods
Single Arm Prospective Cohort Study
All surgical patients of age from 16 years to 70 years, who were
scheduled for open abdominal surgery, were eligible for the study, given
their ability to understand the nature of study and grant written informed
1.Re-laparotomy within 30 days of primary surgery due to reasons
other than related to wound infection
2. Midline for transverse laparotomy within 60 days of registration for
3. Abdominal operation without midline or transverse laparotomy
(For Example, appendectomy)
4. Concurrent Abdominal wall infections
5. Severe Immunocompromised state
a) After organ or bone marrow transplantation
b) Concurrent Steroid Treatment with > 10 mg Prednisolone daily (or
an equivalent dose of any other steroid)
c) Chemotherapy within last two weeks
d) Pre-operative Neutropenia < 0.5 x 109 Cells/L
6. ASA >3
Sample size was calculated based upon evidence from study of Pinkney
TD et al who reported incidence rate of surgical site infection to be 24.7%
in laparotomy patients . Keeping level of significance to be 5% and
precision to be 10%, sample size calculated turned out to be 72 patients.
Expecting loss to follow up rate upto 10%, we included 80 patients in
The study was conducted at the General Surgical Units of The Aga
Khan University Hospital (AKUH) Karachi. AKUH is a 550 bed tertiary
care hospital with eight general surgeons. All the patients who fulfilled
eligibility criteria were approached to be included in the study. If consent
was granted, the patient was included in the study.
Non probability consecutive sampling.
In patients participating in the study, a sterile circular non-adhesive
plastic sheet was applied circumferentially to wound edges before
application of abdominal wall retractors. This sheet was taken from C
Arm cover. In its original form, it is tubular cover of diameter of about
20 Inches, made up of polyethylene. 8-10 Inches length of this was cut
and used as wound protector. It is improvisation of commercially available
wound protectors. This sheet acted as physical barrier to direct contact of
intra-abdominal contents with laparotomy wound edges.
Data collection procedure
All patients who fulfilledthe eligibility criteria were included in the
study. Pre-operative and post-operative antibiotics were given as per
protocol. Standard aseptic and anti-septic preparation was done.
Data regarding the demographics of the patients was collected on
specifically designed questionnaire. Wound was assessed daily from
second day onwards during the hospital stay and on clinical follow up
after discharge from hospital to detect surgical site infection according
to CDC criteria. Either of the superficial and deep SSI was considered as
positive outcome. Last assessment was made 30 days after the surgery.
Data was entered and analysed using SPSS version 19 . Continuous
variables i.e. age, White Blood Cells count, duration of surgery and
duration of hospital stay are reported as means +/- standard deviation.
Categorical variables i.e. gender and Surgical Site Infection are reported
as percentages and proportions. Reported infection rate of 6.7% after
laparotomy in previously reported data from our institution was used
as standard to compare our results with . One sample proportion
comparison test was used to detect statistically significant difference from
reported rate of surgical site infection.Chi-Square test was applied as test
of significance to detect change in risk of surgical site infection. “p” value
of less than 0.05 was considered as significant. To detect independent
predictors of surgical site infection, we used univariate and multivariable
binomial logistic regression analysis.
Criteria for defining surgical site infection (SSI)
Surgical site infection was defined using criteria laid down by Centre
for Disease Control and Prevention . Salient features of these criteria
are given below and outcome was considered positive if any one of both
criteria was fulfilled.
Superficial incisional SSI: Infection that occurs within 30 days after
the operation and infection involves only skin or subcutaneous tissue of
the incision and at least one of the following:
1. Purulent drainage, with or without laboratory confirmation, from
the superficial incision.
2. Organisms isolated from an aseptically obtained culture of fluid or
tissue from the superficial incision.
3. At least one of the following signs or symptoms of infection: pain
or tenderness, localized swelling, redness, or heat and superficial
incision is deliberately opened by surgeon, unless incision is culturenegative.
4. Diagnosis of superficial incisional SSI by the surgeon or attending
physician based on above findings.
Deep incisional SSI: Infection occurs within 30 days after the operation
if no implant is left in place and the infection appears to be related to the
operation and infection involves deep soft tissues (e.g., fascial and muscle
layers) of the incision and at least one of the following:
1. Purulent drainage from the deep incision but not from the organ/
space component of the surgical site.
2. A deep incision spontaneously dehisces or is deliberately opened by
a surgeon when the patient has at least one of the following signs or
symptoms: fever (>38ºC), localized pain, or tenderness, unless site
3. An abscess or other evidence of infection involving the deep
incision is found on direct examination, during reoperation, or by
histopathologic or radiologic examination.
4. Diagnosis of a deep incisional SSI by a surgeon or attending
physician based on above findings.
Laparotomy wound edge
Laparotomy wound edge was defined as surgical incision margin on
anterior abdominal wall from skin to peritoneum.
Data collection was started from April 2016 to Nov 2016. All consecutivepatients who were planned for laparotomy and met our inclusion criteria were invited to participate in the study. During data collection period,
a total of 128 laparotomies were done. A detail of these laparotomies is
given in the following flow diagram figure 1.
Mean age of the patients included for study was 48.8 +/- 15.8 years.
Of the participants 49 (64.5%) were males and 27 (35.5%) were females.
In our study, laparotomy was done after elective admission in 49 (64.5%)
patients, while rest of 27 (35.5%) had admission through emergency.
Systemic Inflammatory Response Syndrome or Sepsis was present in
39 (51.3%) patients before undergoing operation. Categorizing based
upon degree of intra-operative contamination, 17 (22.3%) patients had
contaminated or dirty operation. Mean duration of operation was 190 +/-
115 minutes and 27 (35.8%) patients were having > 2 American Society of
Anesthesia (ASA) category.
In our study, 7 (9.2%) patients developed laparotomy wound infection.
Out of these 7 patients, 3 had superficial surgical site infection while 4 had
deep surgical site infection.
We checked if our infection rate was different from previously reported
infection rate after abdominal surgery by Pishori et al from the same
hospital . In report of that surveillance surgical site infection was
reported to be 6.7% after abdominal surgeries. One sample proportion
comparison test was used to test if our infection rate was significantly
different from 6.7%. No statistically significant difference was found in
our infection rate from reported rates (p=0.81).
Figure 1: Flow Diagram Showing Selection based upon eligibility Criteria
Individual predictor variables were checked for association with
development of surgical site infection. For binomial categorical variables,
results are as given in table 1.
Results showed that mode of admission and SIRS or Sepsis present
before admission were significantly associated with development
of surgical site infection. There was no association of gender with
development of surgical site infection.
For polynomial categorical predictor variables association was checked
It was found that degree of intra-operative contamination was
significantly associated with development of surgical site infection
(P < 0.05). Categories based upon degree of contamination and their
frequencies of developing surgical site infection along with percentages
are as given in table 2.
Results of analysis of association between degree of intra-operative
contamination and development of surgical site infection showed that
greater the degree of contamination more are the chances to develop
surgical site infection.
Frequency of developing surgical site infection according to ASA
categories are given in table 3.
Results of analysis of ASA categories showed that greater the ASA category,
more are the chances for a patient to develop surgical site infection.
Results of analysis of quantitative predictor variables showed that age,
TLC count before surgery and length of hospital stay were not significantly
associated with development of surgical site infection. Results showed
that those who developed surgical site infection had significantly shorter
duration of operation as compared to those who did not develop surgical
In order to see the effect of individual variables adjusting for other
predictor variables, binomial logistic regression was done. All the
variables which turned out to be significant at univariate analysis were
considered for inclusion in multivariable binomial logistic regression
analysis. Model building was done adopting forward regression technique,
including variables in the model in order of their significance level.
Variables considered for multivariable regression analysis included, mode
of admission, SIRS / Sepsis before operation, degree of intra-operative
contamination, ASA category and duration of operation. Results of final
model obtained are as shown in table 4.
Who did not Develop SSI (%)
Who Developed SSI (%)
Mode of Admission
SIRS / Sepsis
Table 1: Relationship of binomial predictor variables with development of
Surgical Site Infection
Who did not Develop SSI (%)
Who Developed SSI (%)
Clean Contaminated (46)
Table 2: Frequency of Surgical Site infection according to degree of intraoperative
Who did not Develop SSI
Who Developed SSI (%)
Table 3:Frequency of Surgical Site Infection according to ASA Categories
Degree of Intra-operative Contamination
Table 4:Multiple Binomial Logistic Regression Analysis to adjust for covariates
Final model included only Degree of intra-operative contamination to
be significantly associated with development of surgical site infection
In terms of relative risk, risk of developing surgical site infection for
clean contaminated, contaminated and dirty surgeries as compared to
clean surgeries turned out to be 2.5, 5.6 and 13.0 time in our data.
Surgical site infections after abdominal operations prove to be a
significant morbidity especially after clean abdominal operations. This
is especially true of low income countries where morbidity is burden
on the pocket as well. Aga Khan University reported its infection rates
after various surgical procedures in 2001. This was made possible by
establishing a surveillance system to monitor surgical site infections. Rate
of abdominal wound infection overall was reported to be 6.7% .
In the last decade there has been some literature regarding effectiveness
of wound protection during surgery, especially after laparotomy. There
is lack of conclusive evidence yet regarding its true impact. Wound
protectors are available commercially as well. Drawback of these wound
protectors is that they are economically no affordable for low income
country people. To overcome that problem, we devised a custom made
wound protector. It was made from polyethylene tubular sheet used to
cover fluoroscope during intra-operative fluoroscopy. We cut a length of
8-10 cm of that tubular sheet. One end of the sheet was placed inside the
abdomen after doing laparotomy and the other end stayed outside. Selfretaining
retractors were applied after placing in the wound protector. We
checked effectiveness of this wound protector in preventing surgical site
Our study reported infection rates after abdominal surgeries to be
9.2%. This infection rate is higher than previously reported rates from the
same institution. This difference was not statistically significant.
Over a period of time, trend has been seen that, patients are referred to
tertiary care hospital from remote areas usually when their disease either
has become severe or they have tried modes of treatment other than
allopathty. Immuno-compromization due to those treatments and severity
of illness could be a factor for higher infection rates in our population, and
worsening of these figures over time.
About one third of our patients had admission through emergency.
Emergency operation is a known risk factor for surgical site infection .
Our study also showed that about one quarter of patients
had contaminated or dirty operations. Degree of intra-operative
contamination, which is also correlated with more emergency admissions,
could be one of the underlying factors responsible for increased infection
rates in our population.
While comparing our results with international literature, our
result correlate with studies by Smith et al and Edward et al, who
also demonstrated that wound protection has no advantage over no
protection after abdominal surgeries [17,18]. These studies had used
wound protectors that were commercially made for this purpose which
functioned as protectors as well as retractors.
There have been prospective studies from various countries reporting
effectiveness of barrier wound protection. Some of these studies claim that
wound protection results in decrease in surgical site infection rate after
wound protection [8,10].
A meta-analysis of published literature upon this topic analysed the
combined data of similar prospective studies. This meta-analysis showed
that there was significant difference between rate of surgical site infection
after barrier wound protection .
Our study failed to show any benefit of laparotomy wound edge
protection in reducing rate of surgical site infection. We recommend
prospective randomized controlled trial to evaluate rote of barrier wound
We conducted a single arm prospective study comparing our results
with historical cohort of patients for which infection rates are reported.
Limited information available of patient population of historical cohort
and along with limited follow up is the main limitation of the study.
Conflict of Interest
We have no conflict of interest
Funding for the project was provided from Faculty Research Fund.
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