by 
Sanders DL, Pawlak MM, de Beaux AC. European Hernia Society incisional hernia guidelines. Br J Surg. 2023;110:343–343. https://academic.oup.com/bjs/article/110/3/343/6970433
Introduction
A meta-analysis including over 14 000 patients reported a weighted incidence of 12.8 per cent 2 years after a midline incision, and that one-third of patients with an incisional hernia undergo surgical repair.
Eligibility criteria
Eligibility criteria for inclusion in the guidelines were adult (greater than 18 years) patients with a primary incisional hernia; with a no larger than 10 cm fascial defect.
Key Question 1: What are the risk factors for developing an incisional hernia after previous abdominal surgery?
Good Practice Statement A: Patients should be advised that high BMI, smoking, diabetes, and immunosuppression are risk factors for developing an incisional hernia after abdominal surgery.
Good Practice Statement B: Surgeons should be aware that midline incisions have a higher risk of incisional hernia than off-midline incisions.
Good Practice Statement C: Surgeons should be aware that single incision laparoscopic surgery (SILS), trocar sites 10 mm and larger, and umbilical site trocars have a higher risk of incisional hernia (trocar-site hernias).
Good Practice Statement D: Surgeons should be advised that the combination of a continuous small-bites suturing technique with a slowly absorbable suture reduces the risk of incisional hernia.
Good Practice Statement E: Surgeons should be aware that surgical site infection (SSI) after abdominal surgery is a risk factor for developing an incisional hernia and appears to have the biggest impact when compared with other risk factors.
Explanation
Pooled data comparing off-midline (transverse and paramedian) versus midline incision with a median follow-up of 30 months were generated using a meta-analysis with a low certainty of evidence. The risk of an incisional hernia in the midline group was 10.0 per cent (106/1058 patients) compared with 5.2 per cent (65/ 1240 patients) in the off-midline group (Relative risk (RR) 0.47; 95 per cent c.i. 0.3 to 0.75).
A total of 32 RCTs were identified that compared incisional hernia (port site hernia) after SILS versus conventional laparoscopic surgery. The overall certainty of evidence was low. Pooled analysis revealed a risk of developing an incisional hernia of 1.5 per cent (27/1861 patients) with SILS versus 0.5 per cent (11/2156 patients) with conventional laparoscopic surgery (OR 1.92 (95 per cent c.i. 0.94 to 3.91)).
A total of nine studies assessed the impact of SSI as a risk factor for developing an incisional hernia. Pooled analysis suggested a risk of incisional hernia of 19.4 per cent (76/391 patients) after having an SSI compared with 6.9 per cent (315/ 4542 patients) with no SSI (OR 3.38 (95 per cent c.i. 2.18 to 5.23)).
Key Question 2: (a) Do all patients with an incisional hernia require imaging? and (b) What is the best modality?
Recommendation A: For patients with a suspected incisional hernia where clinical examination has not given a definitive diagnosis, medical imaging to establish the diagnosis is suggested; from the evidence CT is the most sensitive investigation.However, if the cost and radiation exposure are a concern then ultrasonography or MRI with Valsalva is suggested (conditional recommendation, low certainty evidence).
Good Practice Statement B: For patients with an incisional hernia (where surgery is being considered), the guidelines panel recommends using CT or MRI for preoperative planning.
Explanation
A total of four cross-sectional studies were extracted from the Kroese et al. systematic review that directly compared CT with physical examination. When compared with CT, physical examination was found to have a sensitivity between 0.48 and 0.81, and a specificity between 0.9 and 0.95.
Key Question 3: Is it possible to predict from imaging whether the fascial closure will be possible?
Recommendation A: The guidelines panel suggests that it is not possible to accurately predict with CT whether the fascial defect can be closed without myofascial release (component separation) or peritoneal flap technique (conditional recommendation, very low certainty evidence).
Good Practice Statement B: For patients with a midline incisional hernia, it is likely that the fascia will not be able to be closed without myofascial release if on preoperative CT any of the following apply: the defect width is over 8 cm; the area of the hernia is over 164 cm2; the rectus/defect ratio is less than 1.34; or the component separation index (CSI) is over 0.146. For hernias approaching or above these measures, the guidelines panel suggests that only surgeons who are competent in advanced techniques such as component separation or peritoneal flap should perform surgery.
Key Question 4: (a) Do all incisional hernias need surgical treatment? and (b) What are the important outcome measures in treatment of incisional hernias?
Good Practice Statement A: For patients with a reducible midline incisional hernia, the risk of an acute hernia accident (strangulation or bowel obstruction) is low (1 per cent in the first year and 2.5 per cent by 5 years).
Good Practice Statement B: For patients with symptoms that adversely affect their quality of life (and are medically fit enough for surgery), the guidelines panel suggests surgical repair; after detailed discussion with the patient about the risks and benefits of surgery or watchful waiting.
Good Practice Statement C: For patients undergoing treatment for an incisional hernia, the guidelines panel suggests that the most important outcome measure is quality of life. The most important components of quality of life may vary between patients.
Good Practice Statement D: For patients undergoing treatment for an incisional hernia, the guidelines panel suggests that other important outcome measures are recurrence, surgical site occurrences, mesh infection, mortality, chronic pain, and cost-effectiveness.
Explanation
In a large observational series of 23 022 people with an incisional hernia undergoing non-operative management with follow-up of up to 8 years, the risk of an acute hernia event at 1 year was 1.24 per cent, increasing to 2.59 per cent by 5 years. Crossover to elective incisional hernia repair due to symptoms was analysed at two time points, within 3 months from diagnosis (early crossover) and between 3 months and 5 years after diagnosis (late crossover). Crossover at these time points was 21.9 and 9.8 per cent respectively.
Key Question 5: (a) What are the important modifiable risk factors that should be optimized before surgery? and (b) What is the effect of pre-optimization?
Good Practice Statement A: For patients undergoing treatment for an incisional hernia, the important modifiable risk factors are high BMI, poorly controlled diabetes, and smoking.
Good Practice Statement B: For patients undergoing treatment for an incisional hernia, the guidelines panel recommends patient pre-optimization before surgery. This includes targeted weight loss (if high BMI), good diabetic control (measured by HbA1c), smoking cessation, and improved pulmonary fitness.
Good Practice Statement C: For patients with a symptomatic incisional hernia who are unable to lose weight after a dedicated weight loss programme over a pre-optimization interval and where surgery is technically possible, the guidelines panel suggests that the increased risks of delaying surgery (worsening quality of life and enlarging fascial defect) may outweigh the benefits of further weight loss, but this needs careful discussion of the risks and benefits with the patient.
Explanation
In a Cochrane review of 13 RCTs recruiting smokers before elective surgery, again, not specifically ventral hernia repairs, 7 trials looked at the association of preoperative abstinence with postoperative complications. After intensive interventions a reduction in all complications (RR 0.42) and wound morbidity (RR 0.31) was found. However, intervention less than 4 weeks from surgery did not demonstrate a significant impact on morbidity and was less likely to lead to long-term smoking cessation. This would suggest that greater than 4 weeks of smoking cessation is required before surgery.
Key Question 6: What is the difference in outcome for mesh versus suture repair in incisional hernia repair?
Recommendation A: For patients with a midline incisional hernia a mesh-based repair technique is recommended (strong recommendation, very low certainty evidence).
Key Question 7: What is the difference in outcome considering different positions of mesh in incisional hernia repair?
Recommendation A: For patients with a midline incisional hernia, the guidelines panel recommends that mesh should be placed in the retromuscular plane (strong recommendation, very low certainty evidence).
Good Practice Statement A: Surgeons performing incisional hernia repair should be familiar with the technique for positioning the mesh in different planes (including onlay, retromuscular, and intraperitoneal).
Good Practice Statement B: For patients with a midline incisional hernia, the guidelines panel suggests that any mesh in the abdominal cavity exposed to the abdominal viscera should be used with caution due to the risk of long-term complications at any subsequent abdominal surgery.
Explanation
The term retromuscular encompasses both the retrorectus and preperitoneal planes.
Onlay versus retrorectus
Four RCTs of low to moderate quality compared open onlay with retrorectus mesh placement for elective repair of midline incisional hernias. Pooled analysis revealed an increased risk of recurrence, when placing the mesh in the onlay position (7.2 per cent (14/194)) compared with the retrorectus position (2.1 per cent (4/187)). Furthermore, the risk of seroma was increased with the use of an onlay mesh position (33.3 per cent (66/198)) compared with a retrorectus mesh position (13.8 per cent (26/188)). For other wound-related complications such as haematoma and surgical site occurrences, the rates were also higher with the use of onlay mesh.
Holihan et al. in a network meta-analysis of 20 RCTs including both primary ventral and incisional hernias found that retrorectus mesh placement resulted in the lowest risks of recurrence and SSI.
Onlay versus intraperitoneal
Only one small low-quality RCT compared open onlay with open intraperitoneal mesh and concluded that the risk of recurrence was 27.3 per cent (6/22) for onlay versus 0.0 per cent (0/19) for open intraperitoneal with an OR of 15.26 (95 per cent c.i. 0.80 to 293.6). The risk of seroma was 31.8 per cent (7/22) for onlay versus 0.0 per cent (0/19) for open intraperitoneal with an OR of 18.87 (95 per cent c.i. 1.00 to 356.74).
Key Question 8: What is the difference in outcome between techniques (open, laparoscopic, and robotic) for incisional hernia repair?
Good Practice Statement A: For patients with a midline incisional hernia, the guidelines panel suggests that laparoscopic, robotic, or open surgery may be appropriate depending on the patient and hernia characteristics and provided the surgeon has appropriate expertise.
Key Question 9: Is there a benefit of primary fascial closure in midline incisional hernia mesh repair?
Recommendation A: For patients having repair of a midline incisional hernia (laparoscopic or open repair), the guidelines panel recommends that the fascial defect should be closed and bridging with a mesh should be avoided (strong recommendation, low certainty evidence).
Key Question 10: What is the difference in the outcome using different techniques for mesh fixation in (a) intraperitoneal and (b) extraperitoneal mesh placement for incisional hernia repair?
Good Practice Statement A: For patients undergoing surgery using a laparoscopic intraperitoneal onlay mesh, the guidelines panel suggests that a variety of methods including glues, tacks, and sutures (both absorbable and non-absorbable) are possible, with little difference in clinical outcomes.
Good Practice Statement B: For patients having an open retrorectus repair of a midline incisional hernia, whilst the original description described the use of transfascial
sutures, the guidelines panel suggests that other options such as fixation to the posterior layer or self-fixing meshes are acceptable and may reduce the risk of chronic pain.
Key Question 11: What is the benefit of enhanced recovery after surgery (ERAS) in incisional hernia repair?
Good Practice Statement A: For patients having repair of a midline incisional hernia, the guidelines panel suggests that there is not sufficient evidence to recommend enhanced recovery protocols.
Key Question 12: Should prophylactic antibiotics be used in the elective repair of incisional hernia in adult patients?
Recommendation A: For patients having repair of a midline incisional hernia, the guidelines panel suggests a single prophylactic dose of antibiotic (according to local hospital policy). If the operation is longer than 4 h, the guidelines panel suggests a second prophylactic dose, depending on the antibiotic used, amount of blood loss, and surgical approach (conditional recommendation, very low certainty evidence).
Key Question 13: (a) What information is important for patients after incisional hernia repair? and (b) What activities influence outcome?
Good Practice Statement A: For patients having repair of a midline incisional hernia, the guidelines panel states that there is a lack of evidence-based information to provide patients with after surgery.
Good Practice Statement B: For patients having repair of a midline incisional hernia, the guidelines panel suggests: analgesia and dressing management should be as per local hospital policy; patients should be encouraged to actively mobilize and can do as they feel able (including sexual activity); patients should avoid heavy lifting/exercise (where they have to Valsalva) for 4 weeks (time for mesh ingrowth); patients should not swim in a public pool or the sea until the wound has healed (approximately 2 weeks) (however, can shower from day zero); patients can drive when they are able to safely perform an emergency stop without hesitation (advised to inform motor insurance company); and patients can be provided with an abdominal binder or compression clothes to wear for their comfort for first 6 weeks (advised to keep clean).