Is the surgical site infection rate higher in sublay or onlay mesh repair of incisional hernia?

A best evidence topic has been constructed using a described protocol. The three-part question addressed was: In mesh repair of incisional hernia, which technique has a lower rate of surgical site infection (SSI), Sublay or Onlay? The best evidence showed that there is no statistically significant difference in the rate of SSI among the two techniques.


Introduction
This BET was designed using a framework outlined by the International Journal of Surgery [1]. This format was used because a preliminary literature search suggested that the available evidence is of insufficient quality to perform a meaningful meta-analysis. A BET provides evidence-based answers to common clinical questions, using a systematic approach of reviewing the literature.

Clinical scenario
You are consenting a 56 year old male with incisional hernia, for open mesh repair. The patient is known diabetic and he is on immunosuppressant for a previous renal transplant, he is quite concerns about post-operative wound infection.

Search outcome
A total of 54 articles were identified after the removal of duplicates. Of these 40 were excluded on the basis of title and abstract. After fulltext assessment of 14 articles another 8 articles were excluded because they did not include the information needed to compare the two techniques. A total of 6 articles (3 randomized controlled trials, one prospective and 2 retrospective studies) were identified to provide the best evidence to answer the question.

Result
See the table. Table. 1

Discussion
Repair of incisional hernia is regarded as one of the most challenging general surgical procedure, due to the high recurrence rate and postoperative morbidity [2]. Open mesh repair (onlay and sublay technique) is proved to be superior to suture repair [3]. However due to the presence of mesh this technique is not without morbidity such as wound complication like seroma formation and infection [4]. In this article, we have reviewed the best evidences which compare the rate of surgical site infection among Onlay and Sublay techniques.
In 2012, Venclauskas et al. [5] conducted a randomized control trial to evaluate the rate of SSI among onlay and sublay group, their conclusion was that sublay technique has statistically significant lower rate of SSI compared to Onlay technique. In contrast to these findings, Saeed et al. [6] in 2014 published a retrospective study showing that the incidence of wound infection is actually significantly higher among the Sublay rather than the Onlay group.
However, despite these contradicting results, four studies in our review including two randomised controlled trials showed no statistically significant difference in SSI rate between Only and Sublay mesh repair these studies were conducted by Sevinç et al., Manzoor et al., .

Clinical bottom line
The best evidence showed no statistically significant difference in SSI rate between only and Sublay mesh repair of incisional hernia.

Limitation of this review
1 Small sample size in most articles 2. Shorter period of follow in most articles. 3. Nothing mentioned in all articles about the methods of diagnosis of SSI.

Ethical approval
Not applicable.

Sources of funding
None.

Author contribution
RI: conducted the literature search and wrote the paper. SA: assisted in the literature search and Writing of paper. TA: assisted in writing of paper.

Consent
Not applicable.

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