**3.1 Surgical site infection**

Surgical incisions are made under sterile conditions, however multiple infection prevention measures must be observed pre-, post-, and intraoperatively to minimize risks of post-operative infections. Surgical site infection (SSI) is the most common

surgical wound complication, affecting up to one-third of patients who have undergone a surgical procedure [11]. SSIs are commonly classified as one of three types: superficial incisional (involving only the skin or subcutaneous tissue of the incision), deep incisional (involving the deep soft tissues of the incision, such as fascia and muscle layers) or organ/space (involving any part of the anatomy which was opened or manipulated during an operation other than the incision) [5]. It has been estimated that two-thirds of SSI are confined to the incision [5].

Infection occurs when microorganisms in a wound proliferate to a level that produces a local and/or systemic response [12]. Many of the factors that impact surgical wound healing also affect the potential for infection. Risk factors for SSI include patient-specific and process/procedural-specific variables. Some variables are not modifiable, such as patient age and gender, however, others can be improved to reduce the risk of infection such as nutritional status, tobacco use, correct timing and dosing of antibiotics and aspects of intraoperative technique [11]. A particular risk factor for SSI is the presence of foreign bodies in the wound which can provide a surface for bacteria colonization and biofilm formation [13]. While such foreign bodies are often thought to be exemplified by larger, permanent implantable medical devices such as joint protheses or heart valves, devices for wound closure such as surgical sutures can present similar risks for surgical wound infection [13]. Clinical data as early as the 1950s has shown that the presence of suture in an incision can reduce the infective dose of bacteria by 10,000-fold; from a dose of millions down to hundreds [14]. The rationale for this is that within hours, small numbers of bacteria released into the wound from lower layers of the stratum corneum and dermal appendages during creation of the surgical incision can colonize the suture surface and develop into a biofilm which is resistant to phagocytic immune cells as well as to antibiotics [15].

Surgical site infections are the most common of all healthcare associated infections (HAI) [16]. A 2022 retrospective analysis of the largest all-payer US inpatient databases—the Agency for Healthcare Cost and Utilization Project's 2016 National Inpatient Sample, provides some of the most up-to-date information on the incidence of HAI [16]. This database covers more than 97% of the US population and contains data from more than 35 million inpatient admissions [16]. The analysis considered all inpatient encounters with primary or secondary ICD-10 diagnosis codes corresponding to infection with catheter-associated urinary tract infections (CAUTI), catheter- and line-associated bloodstream infections (CLABSI), SSI, ventilator-associated pneumonia (VAP), and infection with *Clostridioides difficile* (CDI) to determine incidence [16]. For the 280,575 admissions with HAI as a primary diagnosis, SSI was the most frequent at 47%, followed by CDI as 37.4%, CLABSI at 10.2%, CAUTI at 5% and VAP at 0.4% [16]. The additional costs associated with these SSI were 3.7 billion USD [16].

#### **3.2 Surgical wound dehiscence**

Surgical wound dehiscence (SWD) is a wound healing complication that has a wide range of definitions [17]. It can refer broadly to any separation of a surgical incision ranging from a superficial separation of part of the incision to complete separation of the full thickness of the incision with exposure of organs or surgical implants [17]. Conversely, the term can be used specifically to describe the failure of an abdominal incision and evisceration of the abdominal contents [17]. Further, literature reports may use a variety of alternative descriptors for SWD such as wound disruption, wound opening, wound breakdown, fascial dehiscence, or surgical site failure, among others [17]. A standardized definition of SWD for all closed surgical

#### *Surgical Wound Closure and Healing DOI: http://dx.doi.org/10.5772/intechopen.105978*

incision types was proposed in 2018 by the World Union of Wound Healing Societies to facilitate accurate identification and reporting as well as management [17]. The definition is as follows: "Surgical wound dehiscence (SWD) is the separation of the margins of a closed surgical incision that has been made in the skin, with or without exposure or protrusion of underlying tissue, organs, or implants. Separation may occur at single or multiple regions, or involve the full length of the incision, and may affect some or all tissue layers. A dehisced incision may, or may not, display clinical signs and symptoms of infection" [17].

Dehiscence can be caused by technical issues with incision closure such as failure of the closure material or technique, postoperative mechanical stresses placed on the incision by local edema or patient activity levels, endogenous healing issues or any combination of these [17]. There is also a correlation between SWD and other surgical wound complications, such as seroma, hematoma, incisional hernia, and SSI [17].

Determination of SWD incidence is hampered by the lack of a uniform definition and rates in the literature vary widely by surgical procedure type and surgical wound classification [17]. SWD rates have been reported to range from 0.65% in cardiothoracic surgery up to 41.8% in pilonidal sinus surgery [17].

## **3.3 Incisional hernia**

Incisional hernias (IH) are a common surgical wound complication after abdominal surgical procedures (especially midline incisions) and are defined as "abdominal wall gaps around postoperative scars, perceptible or palpable by clinical examination or imaging" [18]. Incisional hernias develop because of the failure of the abdominal wall to close properly due to patient related factors, disease related factors and or technical factors related to surgical technique or wound closure materials [19]. Wound infection, obesity, and suture closure technique (in particular a suture length/ wound length ratio > 4/1) are thought to be the most important risk factors for the development of IH [19].

The incidence of IH after midline laparotomy ranges from 0 to 44% in the literature; however, a pooled rate of 12.8% has been reported at two years postoperatively from a systematic review and meta-analysis of 56 papers involving 14,618 patients [18].
