Impact of Surgical Site Infections on Elective Incisional Hernia Surgery: A Prospective Study

Abstract

Background:

Although incisional hernia repair is classified as a clean surgery, it still has a high incidence of surgical site infection (SSI) (0.7%–26.6%). The presence of an SSI could increase early recurrence rates after incisional hernia repair.

Patients and Methods:

Patients undergoing elective incisional hernia repair with no bowel contamination between January and December 2015 were assessed prospectively. Demographic and surgical data, local post-operative complications, and one-year recurrence rates in patients with and without SSI were compared. The management of SSI was determined.

Results:

Patients with SSI (16/101) showed more prolonged surgical procedures (91 ± 39 vs. 63 ± 30 min, p = 0.012), more post-operative sero-hematomas (38% vs. 8%, p = 0.001), and a higher one-year recurrence rate (19% vs. 4%, p = 0.047). Multivariable analysis revealed the only identified risk factor for SSI to be post-operative sero-hematomas (p = 0.042; odds ratio [OR] = 4.17 [1.05–16.54]). Patients who developed an SSI required antibiotic agents and daily treatment from one to five months. One of these required the removal of the mesh.

Conclusions:

Surgical site infection rates are high for incisional hernia surgery (16%), and associated with local complications. Surgical site infection requires long-term treatments and leads to a higher one-year recurrence rate.

Although incisional hernia surgery is classified as a clean surgery, surgical site infection (SSI) rates range between 0.7% and 26.6%. This high variability could be explained by differences in patients' characteristics, hernia complexity, surgical techniques, and diagnostic criteria [1,2].

Corticoid intake, immunosuppression, ischemic heart disease, chronic obstructive pulmonary disease (COPD), hypoalbuminemia, and age have been assessed previously as SSI risk factors [3,4]. Surgical technique-related factors, surgical access, incisional hernia type (size and complexity), type and location of the mesh, post-operative local complications, operating time, magnitude of subcutaneous surgical dissection, use of drainages, and emergent or contaminated operations have all been correlated formerly to SSI [4].

The development of an SSI entails long and costly treatments, which include daily treatment, antibiotic agents, negative-pressure wound therapy (NPWT) on a closed incision using a vacuum dressing, and in some cases, the removal of the mesh [5]. Furthermore, SSI may also increase recurrence rates after incisional hernia surgery [6]. Reducing SSI rates is a priority for all of these reasons. This in turn will help surgeons to reduce damages and costs, improve patients' quality of life, and slow the development of new bacterial resistance.

The main objectives of the present study were to analyze SSI-related factors and the impact of an SSI on the one-year recurrence rate. A secondary objective was the reporting of SSI management.

Patients and Methods

Patients undergoing elective incisional hernia repair between January and December 2015 were assessed prospectively. Exclusion criteria were emergent procedures and contaminated or dirty surgeries. The objective was to study a homogenous sample of patients with the same physiopathology for SSI. All patients gave their prior informed consent, and surgical procedures were performed by surgeons with no special commitment to abdominal wall surgery.

Prophylactic protocol in our hospital

Prophylactic protocol included the use of a single dose of cefazoline, 2 g, within 30 minutes of the surgical incision [7]; hair removal with a clipper [8]; a shower before surgery using a plain soap [9]; iodine aqueous-based antiseptic solutions for surgical site skin preparation; a change of gloves by the surgeons and their team before mesh application [10]; and saline irrigation of incisional wounds with 500 mL of 0.9% saline serum [11]. The mesh was made of polypropylene with a large pore (3.6 × 2.8 mm; > 2000 mcm) and low density, 48 g/m² (Optilene Mesh Elastic^®; B. Braun Surgical SA, Rubí, Spain).

Data collection

Patient analysis included the following criteria: age, gender, body mass index (BMI) [12], obesity (considered as BMI >30 kg/m²), anesthetic risk by American Society of Anesthesiologists (ASA) classification [13], smoking habits, and other comorbidities (hypertension, diabetes, COPD and anti-platelet agents and anticoagulants intake). For the incisional hernia evaluation, European Hernia Society (EHS) classifications including width (W) and length (L) were used [14]. The surgical review recorded surgical technique, location and size of the mesh, operating time, use of drainages, and anesthetic type. The duration of hospitalization was also determined.

Post-operative follow-up

Post-operative complications and early recurrence were evaluated during hospitalization and then at 7 and 30 days and 6 and 12 months after the surgical procedure. Complications were analyzed by Clavien-Dindo classification [15]. Local complications such as SSI (following U.S. Centers for Disease Control and Prevention [CDC] definitions [16]) and post-operative seroma and hematoma [17] were considered. Systemic complications (hemodynamic, respiratory, urinary, and mortality) were also assessed. Hernia recurrence was evaluated by surgeon's clinical evaluation and abdominal computed tomography (CT) during the consultations after discharge. Patients who presented with an SSI were compared with those who did not.

Statistical analysis

Continuous data were summarized as mean ± standard deviation. Comparison of means was performed by Student t-test or non-parametric analysis. Contingency tables and χ² and Fisher tests were used for the analysis of qualitative variables. A multivariable analysis with a statistic model was accomplished, including the odds ratio for statistically significant variables. Statistical analysis was carried out using SPSS statistical package version 18 (SPSS Inc., Chicago, IL), and p values <0.05 were considered statistically significant.

Results

The study included 101 patients. Five patients had been excluded in the course of the study (two were operated emergently and three needed enterotomy or bowel resection, which is classified as contaminated surgery). Table 1 summarizes the demographic and surgical data of the sample. In 55% of the included patients, the incisional hernia was repaired by Rives' surgical technique [18], with the mesh placed on a sublay location. The surgical access was laparoscopic in 2 of these 101 patients, ensuring the closure of the peritoneum after the mesh placement.

Table 1.

Demographic and Surgical Data

n = 101
Demographic data
Age (years)	64 ± 13
Female gender	57
BMI (kg/m²) mean ± SD	27.8 ± 11.2
BMI (kg/m²) categorical	< 25 kg/m²: 14
	25–30 kg/m²: 43
	31–40 kg/m²: 34
	> 40 kg/m²: 10
ASA classification	I: 7
	II: 85
	III: 9
Other habits and comorbidities	Smoking habit: 16
	Anti-platelet agents or anticoagulant intake: 12
	Arterial hypertension: 57
	Diabetes mellitus: 27
	COPD: 11
Surgical data
Type of incisional hernia	Mid-line vertical: 49
	Trocar site: 42
	McBurney: 4
	Subcostals: 3
	Lumbotomies: 2
	Parastomal: 1
EHS classification	Medium: M1M2 (26); M1M2M3 (22); M3 (21); M3M4M5 (4); M4M5 (9); M1 a M5 (7)
EHS classification	Lateral: L1 (3); L2 (3); L2L3 (4); L4 (2)
Recurrences (previous mesh)	13
Surgical access	Open: 99
Surgical access	Laparoscopic: 2
Location of the mesh	Onlay: 45
Location of the mesh	Sublay: 56
Type of anesthesia	General: 55
	Regional: 42
	Local and sedation: 4
Operating time (min)	67 ± 33
Hernia size (mm)	Width (W): 57 ± 34
Hernia size (mm)	Length (L): 72 ± 50
Mesh size (mm)	Width (A): 125 ± 70
Mesh size (mm)	Length (L): 146 ± 82
Number of drainages	1 (0–3)
Hospitalization (days)	2 (0–12)

BMI = body mass index; SD = standard deviation; ASA = American Society of Anesthesiologists; COPD = chronic obstructive pulmonary disease; EHS = European Hernia Society.

Sixteen patients developed an SSI (16%). Table 2 shows the diagnosis criteria, management, Clavien-Dindo classification, and microbiology of the 16 patients with an SSI. All patients with SSI received antibiotic agents and needed daily treatment of the site (all other types of treatment were considered except NPWT) for one to five months. Three patients required a debridement of the SSI; one underwent NPWT using a vacuum dressing; and one required the removal of the mesh for permanent suppuration one year after surgery. Of the 12 micro-organisms that were isolated, 67% were gram-positive cocci and the antibiotic prophylaxis adequacy was 75%. Thirteen seromas and two hematomas were detected. It is significant that almost half of the seromas (6/13) acquired an SSI. The management of patients who developed seroma and SSI is summarized in Table 2. Of the remaining seven patients with seroma and without SSI, two were treated by site puncture, obtaining a negative culture, and the other five were observed until their condition resolved spontaneously (Clavien-Dindo grade I). One hematoma was related to seroma and SSI and the other required surgical debridement and transfusion (Clavien-Dindo grade IIIa). Our patient group contained no instances of non-intra–operative complications or mortality. Two patients (2%) presented systemic complications (one instance of pneumonia and one of cardiac decompensation; Clavien-Dindo grade II).

Table 2.

Diagnosis, Management, and Microbiology of Surgical Site Infection

	SSI type	Diagnosis	Time of resolution with daily cures (months)	Removal of the mesh	Microbiology	Antibiotic prophylaxis adequacy	Clavien-dindo
Case 1	Superficial	Surgical site suppuration	2	NO	Positive for Staphylococcus aureus MRSA	NO	II
Case 2	Superficial	Purulent surgical site suppuration	2	NO	No cultures	—	II
Case 3	Superficial	Purulent surgical site suppuration (previous seroma)	1	NO	Positive for S. aureus	YES	II
Case 4	Superficial	Swelling, erythema, and heat on the surgical site	2	NO	No cultures	—	II
Case 5	Deep	Pain, local swelling, and surgical purulent debridement (previous seroma)	1	NO	Negative culture	—	IIIa
Case 6	Superficial	Surgical site suppuration	1	NO	Positive for Proteus mirabilis and Streptococcus agalactiae	YES	II
Case 7	Superficial	Pain, local swelling, and surgical site suppuration	1	NO	No cultures	—	II
Case 8	Deep	Spontaneous dehiscence and pain (previous seroma)	2	NO	Positive for S. aureus	YES	II
Case 9	Superficial	Surgical site suppuration (previous seroma)	1	NO	Positive for Finegoldia magna	YES	II
Case 10	Deep	Spontaneous purulent dehiscence	5 Hospitalization and NPWT (vacuum dressing)	NO	Positive for P. mirabilis	YES	II
Case 11	Deep	Continuous surgical site suppuration (previous seroma)	No cure, removal of the mesh	YES	Positive for S. aureus	YES	IIIb
Case 12	Superficial	Surgical site suppuration (previous seroma and hematoma)	2	NO	Positive for P. mirabilis	NO	II
Case 13	Superficial	Erythema, heat and local swelling of surgical site	2	NO	No cultures	—	II
Case 14	Deep	Purulent drainage and surgical debridement of surgical site	5	NO	Positive for Peptostreptococcus asacharolyticus	YES	IIIa
Case 15	Superficial	Erythema and surgical site suppuration	1	NO	Positive for Enterococcus faecalis	NO	II
Case 16	Superficial	Erythema and surgical site suppuration	3	NO	Positive for Veilonella spp.	YES	II

SSI = surgical site infection; MRSA = methicillin-resistant Staphylococcus areus; NWPT = negative-pressure wound therapy.

Patients who manifested an SSI had longer surgical procedures and more post-operative seroma and hematoma. All patients (100%) completed one-year follow-up. Six recurrences (6%) were determined by abdominal CT. Of these, three have already been re-operated. The presence of an SSI was linked to a high probability of one-year recurrence. A multivariable analysis with a statistical model was applied, including the three statistically significant variables encountered in the univariable analysis (operating time, post-operative seroma and hematoma, and one-year incisional hernia recurrence). The only risk factor identified for SSI by the multivariable analysis was the presence of post-operative seroma and hematoma (p = 0.042; odds ratio [OR] = 4.17 [1.05–16.54]; Table 3).

Table 3.

Comparison of Demographic, Surgical, Local Complications, and One-Year Recurrence between Patients with and without Surgical Site Infection

	SSI group (16)	Non-SSI group (85)	p	Multivariable analysis
Demographic
Age (years)	64 ± 13	63 ± 14	0.667
Female gender (%)	7 (44)	50 (61)	0.265
BMI (kg/m²)	30.2 ± 10.6	27.4 ± 11.3	0.219
Obesity (%)	10 (63)	39 (46)	0.222
ASA (%)
I	3 (19)	3 (4)	0.124
II	12 (75)	74 (87)
III	1 (6)	8 (9)
Other habits and comorbidities (%)
Smoking habit	4 (25)	12 (14)	0.274
Antiplatelet agents or anticoagulants intake	4 (25)	9 (11)	0.081
AHT	7 (44)	50 (61)	0.265
Diabetes mellitus	2 (13)	25 (29)	0.161
COPD	0 (0)	11 (13)	0.127
Surgical
Type of incisional hernia (%)
Midline vertical	9 (56)	40 (47)	0.753
Trocar	6 (38)	36 (42)
Other	1 (6)	9 (11)
Sublay mesh location (%)	11 (69)	46 (54)	0.279
Type of anesthesia (%)
General	7 (44)	49 (57)	0.567
Regional	8 (50)	33 (39)
Local and sedation	1 (6)	3 (4)
Operating time (min)	91 ± 39	64 ± 30	0.015^a	p = 0.062
				OR = 1.02 (0.99–1.03)
Hernia size (mm)
Width (W)	65 ± 34	56 ± 34	0.322
Length (L)	91 ± 57	69 ± 48	0.175
Use of drainages (%)	11 (69)	47 (55)	0.318
Local complications
Seroma and hematoma (%)	7 (44)	8 (9)	<0.001^a	p = 0.042^a
				OR = 4.17 (1.05–16.54)
One-year recurrence	3 (19%)	3 (4%)	0.047^a	p = 0.283
				OR = 2.91 (0.41–20.40)

Statistically significant differences.

Inclusion of the multivariable analysis in the right column.

SSI = surgical site infection; BMI = body mass index; ASA = American Society of Anesthesiologists; AHT = arterial hypertension; COPD = chronic obstructive pulmonary disease; OR = odds ratio.

Discussion

In our series, the SSI rate in elective incisional hernia surgery reached 16%; SSI has an effect on one-year recurrence rates. At this point, it is mandatory to reduce SSI rate by enhancing patients' morbidities prior to surgery, ameliorating prophylactic hospital protocols, and seeking out the most advisable surgical procedures. Primarily, it is essential that patient-related factors such as losing weight, giving up smoking, and reaching a proper control of chronic diseases prior to surgical procedure are optimized [19,20].

Regarding prophylactic hospital protocols, the guidelines recommended recently by the World Health Organization (WHO) should be applied for the prevention of SSI. These include, wherever possible, the use of alcohol-based antiseptic solutions or clorhexidine for surgical site skin preparation and the avoidance of hair removal prior to surgery [21]. Surgical site infection in elective incisional hernia surgery is caused mainly by patients' skin micro-organisms, and typically begins at the moment the mesh is placed. At this point, the bad distribution of the endovenous antibiotic used as a prophylaxis (because of the high dissection and bad vascularization of subcutaneous tissue in obese patients and smokers) probably contributes more to the development of the infection than the prophylactic antibiotic coverage [1]. It is hence not unusual for almost 70% of the isolated micro-organisms to be gram-positive cocci (skin micro-organisms) and for antibiotic adequacy to be 75%. For this reason, complementary measures such as topical antibiotic prophylaxis during the surgical procedure could intercede to diminish the SSI rate [22].

On the other hand, there are some surgical technique-related factors that could increase SSI. In our series, operating time and seroma and hematoma were higher in patients who developed an SSI. Traditionally, surgeons have used drains to prevent seroma and hematoma and therefore diminish SSI [17]. However, its use remains controversial, and in some series the use of drainages increases the SSI rate [23 –25]. Sublay techniques are associated with a lower incidence of seromas and SSI, and a lower hernia recurrence rate than onlay techniques. This is likely because they require less dissection of subcutaneous tissue [26,27]. Laparoscopic access is also related to a lower SSI rate [28]. Nevertheless, sublay techniques and laparoscopic access are not used widely among surgeons, perhaps because they require more complex surgical skills and greater capital investment. Complex incisional hernia surgery should be practiced by expert surgeons specializing in abdominal wall surgery [29]. The type of mesh selected is also relevant in the event on an SSI occurring. Polypropylene meshes are the most commonly used in open surgeries. There are no differences in terms of SSI rates between polypropylene and other meshes such as polytetrafluorethylene. However, polypropylene meshes, specifically those with a large pore and low density, have better tolerance to infection and generally do not require removal (94% in our series) [30,31].

In terms of identifying SSI risk factors, this study may be limited by its sample size. Its main strengths, however, are the homogeneity of its prophylactic protocol, the strict appliance of diagnostic SSI criteria, the prospective analysis of data, and its exhaustive patient surveillance (100% at one-year follow-up).

Conclusions

The SSI rate after incisional hernia open surgery is high and related to local site complications. The appearance of an SSI requires long and costly treatments and leads to a higher one-year recurrence rates.

Footnotes

Author Disclosure Statement

No competing financial interests exist for any of the authors.

References

Beffa

, Warren

. Management of mesh infection. In: Hope

, Cobb

, Adrales

(eds.) Textbook of Hernia. Cham, Switzerland: Springer International Publishing, 2017:395–405.

Pérez-Köhler

, Bayon

, Bellón

. Mesh infection and hernia repair: A review. Surg Infect, 2016; 17:124–137.

Liang

, Goodenough

, Martindale

, et al. External validation of the ventral hernia risk score for prediction of surgical site infections. Surg Infect, 2015; 16:36–40

Kaoutzanis

, Leichtle

, Mouawad

, et al. Risk factors for postoperative wound infections and prolonged hospitalization after ventral/incisional hernia repair. Hernia, 2015; 19:113–123.

Berrevoet

, Vanlander

, Sainz-Barriga

, et al. Infected large pore meshes may be salvaged by topical negative pressure therapy. Hernia, 2013; 17:67–73.

Cobb

, Warren

, Ewing

, et al. Open retromuscular mesh repair of complex incisional hernia: Predictors of wound events and recurrence. J Am Coll Surg, 2015; 220:606–613.

Wesley Alexander

, Solomkin

, et al. Updated recommendations for control of surgical site infections. Ann Surg, 2011; 253:1082–1093.

Tanner

, Woodings

, Moncaster

, et al. Preoperative hair removal to reduce surgical site infection. Cochrane Database Syst Rev, 2006; 19:CD004122.

Webster

, Osborne

. Preoperative bathing or showering with skin antiseptics to prevent surgical site infections. Cochrane Database Syst Rev, 2015; 2:CD 004985.

10.

Belkin

. Masks, barriers, laundering and gloving: Where is the evidence?. AORN J, 2006; 84:655–665.

11.

Badia

, Torres

, Tur

, et al. Saline wound irrigation reduces the postoperative infection rate in guinea pigs. J Surg Res, 1996; 334:1209–1215.

12.

World Health Organization. Obesity and overweight: Fact Sheet. Updated January. 2015. www.who.int/mediacentre/factsheets/fs311/en/ (Last accessed January 27, 2018).

13.

American Society of Anesthesiologists. ASA Physical Status Classification System. www.asahq.org/resources/clinical-information/asa-physical-status-classification-System (Last accessed June 2017 ).

14.

Muysoms

, Miserez

, Berrevoet

, et al. Classification of primary and incisional abdominal wall hernias. Hernia, 2009; 13:407–414.

15.

Clavien

, Barkun

, de Olivieira

, et al. The Clavien-Dindo classification of surgical complications: Five-year experience. Ann Surg, 2009; 250:187–196.

16.

Horan

, Gaynes

, Martone

. CDC definitions of nosocomial surgical site infections. Infect Control Hosp Epidemiol, 1992; 13:606–608.

17.

Kaafarani

, Hur

, Hirter

, et al. Seroma in ventral incisional herniorrhaphy: Incidence, predictors and outcomes. Am J Surg, 2009; 198:639–44.

18.

Rives

, Pire

, Flament

, et al. Major incisional hernias. In: Chevrel

(ed). Surgery of the Abdominal Wall. New York: Springer-Verlag Berlin Heildelberg: 1987:116–144.

19.

Rosen

, Aydogdu

, Grafmiller

, et al. A multidisciplinary approach to medical weight loss prior to complex abdominal wall reconstruction: Is it feasible?. J Gastrointest Surg, 2015; 19:1399–1406.

20.

Finan

, Vick

, Kiefe

, et al. Predictors of wound infection in ventral hernia repair. Am J Surg, 2005; 190:676–681.

21.

World Health Organization. Global guidelines for the prevention of surgical site infection. World Health Organization. 2016. www.who.int/gpsc/ssi-prevention-guidelines/en/ (Last accessed June 2017 ).

22.

Heal

, Banks

, Lepper

, et al. Meta-analysis of randomized and quasi-randomized clinical trials of topical antibiotics after primary closure for the prevention of surgical site infection. Br J Surg, 2017; 104:1123–1130

23.

Gurusamy

, Samraj

. Wound drains after incisional hernia repair. Cochrane Database Syst Rev, 2007; 1:CD005570.

24.

Westphalen

, Araújo

, Zacharias

, et al. Repair of large incisional hernias. To drain or not to drain. Randomized clinical trial. Acta Cir Bras, 2015; 30:844–851.

25.

Karamanos

, Kandagatla

, Watson

, et al. Development and validation of a scoring system to predict surgical site infection after ventral hernia repair: A Michigan Surgical Quality Collaborative Study. World J Surg, 2017; 41:914–918.

26.

Timmermans

, de Goede

, van Dijk

, et al. Meta-analysis of sublay versus onlay mesh repair in incisional hernia surgery. Am J Surg, 2007; 6:980–988.

27.

Holihan

, Hannon

, Goodenough

, et al. Ventral hernia repair: A meta-analysis of randomized controlled trials. Surg Infect, 2017; 18:647–658.

28.

Arita

, Nguyen

, et al. Laparoscopic repair reduces incidence of surgical site infections for all ventral hernias. Surg Endosc, 2015; 29:1769–1780.

29.

Poruk

, Hicks

, Trent Magruder

, et al. Creation of a novel risk score for surgical site infection and occurrence after ventral hernia repair. Hernia, 2017; 21:261–269.

30.

Stremitzer

, Bachleitner-Hofmann

, Gradl

, et al. Mesh graft infection following abdominal hernia repair: Risk factor evaluation and strategies of mesh graft preservation. A retrospective analysis of 476 operations. World J Surg, 2010; 34:1702–1709.

31.

Bueno-Lledó

, Torregrosa-Gallud

, Sala-Hernandez

, et al. Predictors of mesh infection and explantation after abdominal wall hernia repair. Am J Surg, 2017; 213: 50–57.