NIHR Signal Fewer wound hernias occur if mesh is used to reinforce abdominal aortic aneurysm surgery
Published on 18 September 2018
Mesh reinforcement may result in patients developing fewer hernias at the incision site after aortic aneurysm surgery. This type of hernia is a common complication of midline (vertical) incisions and can cause pain and restrict everyday activities.
Although using mesh was linked with fewer incisional hernias, this systematic review could not determine with any certainty whether this led to fewer later operations on the hernia. Reoperation carries extra risk, especially in people who have had an aortic aneurysm. Therefore, the presence of hernias may not necessarily lead to more surgery.
While preventing hernias is beneficial, mesh may only be useful for midline incisions, which are less commonly used in the UK than horizontal incisions. These findings provide evidence to support using mesh in appropriately selected patients who may be at high risk of wound hernia.
- Cardiovascular system disorders, Musculo-skeletal disorders, Surgery
Why was this study needed?
An abdominal aortic aneurysm is a swelling or bulge in the wall of the aorta which tends to enlarge, sometimes to the point where the wall ruptures, causing catastrophic bleeding. They are most frequent in men older than 65 years and cause 6,000 deaths each year in England and Wales.
A graft is often used to strengthen the aorta and prevent or treat the bleeding. Depending on the size of the aneurysm and individual factors, the graft is inserted using open surgery, keyhole surgery or endovascular repair through the large femoral vein.
When open surgery is required, there is up to 38% risk of a hernia developing at the incision site if a midline incision is used.
This is the first systematic review and meta-analysis to look at the evidence for use of mesh inserted when closing the wound to prevent incisional hernia.
What did this study do?
The review included four randomised controlled trials of 388 people undergoing open surgery for abdominal aortic aneurysm. Incisions were closed with either mesh reinforcement or standard sutures, and follow-up was for two to three years.
Mesh was placed behind the abdominal muscle in two studies, and in front in one study. The fourth study included separate study groups for each type of placement. It was fixed in place with sutures in three studies and with glue in one study.
Hernia diagnosis included clinical examination in all studies. Two studies conducted imaging in all patients using ultrasound or CT scan, the other two conducted imaging in some, but not all, patients.
The studies generally had low risk of bias.
What did it find?
- Mesh reduced the risk of hernia by 73% (relative risk [RR] 0.27, 95% confidence interval [CI] 0.11 to 0.66; 4 studies, 388 people). Hernias occurred in 25/228 people (11%) who had a mesh compared with 54/160 people (34%) without a mesh.
- Further surgery for the hernia was performed on 1/115 (1%) who had a mesh and 9/123 people without a mesh (7%), but this difference was not significant (RR 0.23, 95% CI 0.05 to 1.05; 3 studies, 238 people).
- Aortic aneurysm operations using mesh were on average 27 minutes longer than operations without mesh (mean difference 27.06 minutes, 95% CI 1.59 to 52.54; 3 studies, 238 people).
- No mesh infections were recorded. Wound infection occurred in 3% of people with mesh and 4% of those without mesh. Seroma – an accumulation of clear fluid under the skin – occurred in 4% of people with mesh and 1% of those without mesh (3 studies, 238 people).
What does current guidance say on this issue?
NICE is developing a guideline on abdominal aortic aneurysm. It is expected to be published in November 2018.
What are the implications?
This study suggests that using mesh may prevent hernia in people having surgery for abdominal aortic aneurysm. In the UK most abdominal incisions are made horizontally, and these have a much lower risk of incisional hernia, but it may be useful for surgeons to know that mesh may be beneficial if they have made a midline incision.
Citation and Funding
Indrakusuma R, Jalalzadeh H, van der Meij JE, et al. Prophylactic mesh reinforcement versus sutured closure to prevent incisional hernias after open abdominal aortic aneurysm repair via midline laparotomy: a systematic review and meta-analysis. Eur J Vasc Endovasc Surg. 2018;56(1):120-8.
This study was supported by the AMC foundation.
British Heart Foundation. Abdominal aortic aneurysm. London: British Heart Foundation.
NICE. Abdominal aortic aneurysm: diagnosis and management. In development [GID-CGWAVE0769]. London: National Institute for Health and Care Excellence; expected publication date Nov 7 2018.
An incisional hernia can be a major complication after open aortic repair leading to pain, disability and even further surgery. Aortic stents and a move towards transverse incisions reduce the risk, but a significant number of UK patients still undergo midline incision for aneurysm surgery. This is often for ruptured aneurysms – some of the sickest surgical patients we encounter.
Although this review shows that mesh reduces the chances of hernias developing after abdominal aortic aneurysm repaired through midline incision, the evidence may not be strong enough to change practice.
Perhaps the most important conclusion is that it confirms that it is reasonable for surgeons to use mesh when it is deemed necessary.
Harvey Chant, Consultant Vascular Surgeon, Royal Cornwall Hospitals
Although this systematic review shows an important reduction in the incidence of incisional hernia using prophylactic mesh reinforcement for midline closures of abdominal aortic aneurysm repair, there are too many unknowns to suggest that this review alone provides sufficient evidence for a change in practice.
First, some hernias were detected using ultrasonography, and many will have been asymptomatic. Second, all the trials were conducted using a suture to wound length ratio of 4:1, whereas a higher ratio currently is recommended. Third, follow up was limited to three years only.
Finally, although there is some evidence that symptomatic incisional hernias are associated with reduction in the physical domains of quality of life, the impact of asymptomatic hernias is unknown.
Professor JT Powell, Imperial College London
Patients who undergo open abdominal repair of abdominal aortic aneurysm via a midline incision are more likely to develop incisional hernias than other patients undergoing abdominal surgery. This may be related to, as yet undefined, connective tissue deficiencies.
Prophylactic inlay of a mesh, either deep or superficial to the rectus muscles, reduces the risk of incisional hernia development. However, there is no evidence that this actually reduces secondary repair rates of hernias. Evidence is also lacking for improved quality of life in patients who receive a mesh.
The need for increased surgical dissection to inlay a mesh; the extra time involved; and association of seromas with mesh, means that this technique is unlikely to be generally accepted into common practice unless more compelling evidence is forthcoming.
Frank CT Smith, Professor of Vascular Surgery & Surgical Education, University of Bristol