Approach to Abdominal Incisional Hernias 
Richard Davis 
 
 
OPEN MANUAL OF SURGERY IN RESOURCE-LIMITED SETTINGS 
www.vumc.org/global-surgical-atlas  
This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License  
 
Background:  
 
Incisional hernias can arise after up to 25% of 
midline laparotomy incisions. Risk factors include 
emergency surgery, wound infection, smoking, 
obesity, and uncontrolled diabetes. Other less 
tangible risk factors include surgical technique and 
patient factors such as collagen formation; there is a 
known association between arterial aneurysmal 
disease and postoperative hernias. Incisional hernias 
can 
range 
from 
asymptomatic 
to 
painfully 
debilitating; most are bothersome and painful to the 
patient because of the associated bulge on Valsalva 
or on standing or coughing. In larger hernias, 
retraction of the lateral abdominal wall muscles leads 
to lack of trunk support and chronic low back pain. 
Especially large hernias can lead to  
 
Incarcerated incisional hernias can be 
chronically 
or 
acutely 
incarcerated; 
acutely 
incarcerated ones represent a surgical emergency. 
Otherwise, 
unincarcerated 
or 
chronically 
incarcerated hernias can be repaired on an elective 
basis, which allows the clinician and patient to agree 
on risks and benefits of repair, as well as to address 
controllable risk factors.  
Patients should stop smoking for 4 to 8 weeks 
before surgery, and HbA1c should be well below 8. 
The wound should be completely free of 
contamination or infection. Situations where this is 
not possible are discussed further below. It is 
extremely difficult for obese people with incisional 
hernias to lose weight because of exercise limitations 
placed by the hernia itself.  
In-depth counseling is in order for the patient 
with prohibitive risk factors, including a very high 
Body Mass Index or severe cardiac or pulmonary 
disease. Surgery may be delayed or deferred in such 
patients. Special attention should be paid, in large 
hernias, to the possibility of loss of domain. In this 
condition, a large hernia has been present for so long 
that the visceral cavity no longer has the size to 
accommodate return of all abdominal contents after 
repair of the hernia. Returning the contents of the 
hernia to the abdominal cavity, if that is even 
possible, will lead to respiratory embarrassment, 
excessive tension on the repair, and even abdominal 
compartment syndrome.  
 
Anatomy:  
 
The arcuate line is a horizontal line located 2-5cm below the 
umbilicus. Above this line, the rectus muscle is surrounded by 
fascia both anteriorly and posteriorly.  
 
 
Below the arcuate line, there is no fascia posterior to the rectus 
muscle. There is only peritoneum and a layer of thin fatty tissue 
called the transversalis fascia. This layer is sufficient to protect 
the bowels from mesh, but is not strong enough to constitute one 
of the layers in a non-mesh hernia repair.  
 
 
The fibers of the external oblique muscle run transversely, from 
superolateral to inferomedial, originating in part above the 
costal margin (blue line.)  
 
Approach to Abdominal Incisional Hernias 
Richard Davis 
 
 
OPEN MANUAL OF SURGERY IN RESOURCE-LIMITED SETTINGS 
www.vumc.org/global-surgical-atlas  
This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License  
 
 
The fibers of the internal oblique muscle run perpendicular to 
the external oblique, transversely from inferolateral to 
superomedial.  
 
 
The fibers of the transversus abdominis run horizontally. The 
innervation of the anterior and lateral abdominal wall runs 
between the internal oblique and the transversus abdominis.  
 
Principles:  
In incisional hernia, the muscles of the lateral 
abdominal wall are no longer attached in the midline; 
they retract and become chronically short in length. 
At the time of repair, it is not advisable to simply re-
approximate them; this approach will fail >50% of 
the time due to excessive tension.  
Any incisional hernia, no matter the size, 
represents a failure in wound healing at the site. 
Often the fascia at the site is attenuated, worsening 
the problem. In these situations, it is necessary to 
incise the shortened muscles, or to place a prosthetic 
mesh, or ideally to do both. Closure of a wound with 
mesh distributes the tension of the wound across a 
larger area than simple closure.  
Placement of a mesh increases the risk of 
complications, which is acceptable because of the 
decrease in risk of recurrence. The surgeon must take 
precautions to minimize the risk of mesh 
complications, the most notable of which is mesh 
infection. 
Another 
well-known 
complication, 
chronic neuropathic pain, is much less common in 
incisional hernia repair compared to inguinal hernia 
repair. Chronic pain after incisional hernia repair is 
best avoided by not securing the mesh with tight 
“encircling” sutures within muscle or fascia, as these 
have the potential to entrap parietal nerves.  
The most commonly available mesh in 
resource-limited settings will be plain polypropylene 
(“Nylon”) mesh. This is classified as “Light” and 
“Heavy.” Light mesh will be more flexible, soft, and 
comfortable to the patient after implantation; this 
comes at a cost of slightly higher risk of hernia 
recurrence.  
Polypropylene mesh may be delivered sterile 
from the manufacturer, or it can be sterilized with 
ethylene oxide. It can also be sterilized in a steam 
autoclave that is functioning properly. See the 
Sterilization chapter for further details.  
If you have high contamination of your 
operating room with dust or flying insects, you will 
have to decide whether the risk of mesh implant is 
higher than the risk of hernia recurrence. If you feel 
that the risk of infection is unacceptably high, the 
component separation technique described in this 
Atlas can be used without mesh placement.  
Approach to Abdominal Incisional Hernias 
Richard Davis 
 
 
OPEN MANUAL OF SURGERY IN RESOURCE-LIMITED SETTINGS 
www.vumc.org/global-surgical-atlas  
This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License  
 
 
 
Positions of mesh placement. 
Onlay (Yellow): Mesh is placed by clearing off the 
anterior rectus sheath, closing the defect primarily, 
and securing the mesh.  
Inlay (Red): Mesh is used to bridge a defect that 
cannot be closed; the mesh is sutured to the edges of 
the fascia.  
Sublay (Purple): Mesh is placed in between the 
rectus muscle and the posterior rectus sheath. Also 
known as Retro-rectus placement, or the Rives-
Stoppa technique. 
Underlay (Green): Mesh is placed within the 
peritoneal cavity, in contact with bowel. Also known 
as Intraperitoneal Onlay Mesh, IPOM. Most 
frequently performed at laparoscopy, using special 
mesh that can be in contact with bowel (See Box, 
“Resource-Rich Settings.”) 
 
Mesh should definitely be avoided in 
situations where: 
● The mesh will come in contact with any body 
fluids such as urine, bile, or bowel contents, 
either during or after the repair. 
● There is any infection at all in the operative field, 
including cellulitis. 
● There is possibility of contact with any bowel 
(exceptions 
as 
per 
box, 
“Resource-Rich 
Settings.”) 
● There has been any entry into a hollow viscus, 
even controlled (cholecystectomy, hysterectomy, 
bowel resection.)  
 
Decision Making: 
Regarding mesh placement, the farther away 
the mesh can be placed from the skin, the safer it will 
be from infection. This will be best accomplished by 
placing the mesh deep to the abdominal wall 
muscles. If plain polypropylene mesh is being used, 
however, it is not acceptable to place this mesh in 
contact with the bowel. Strategies include:  
● In a patient with ample omentum, simply place 
the mesh in an Underlay position and assure that 
the omentum lies between it and the intestines. 
Suture the omentum to the peritoneum around the 
mesh, especially if using a large mesh. 
● Dissect the space between the peritoneum and the 
posterior rectus sheath and place the mesh in this 
space. Preserving the hernia sac helps provide 
coverage of the mesh at the midline when this 
strategy is used. The plane between the posterior 
rectus sheath is very difficult to develop, the 
Sublay position is much easier to accomplish.  
● Place the mesh in the Sublay position, by 
dissecting the posterior rectus sheath off of the 
rectus muscle, as described in the Chapter, 
“Hernia Repair with Sublay (Retro-Rectus) Mesh 
Placement.”  
 
All of these solutions require significant 
dissection and entry into the abdominal cavity, but 
they do offer the most durable and safest repair. 
Conversely, the most appropriate use of the Onlay 
mesh position is in the patient who is not able to 
tolerate a large operation, or in whom the hernia is 
small enough to not warrant a large operation. The 
fascia should be closed and then the mesh laid on top 
of the repair.  
 
Choice of repair type, from the options in this 
Section, will be dictated by the size of the hernia.  
● Hernia Repair with Onlay Mesh Placement is 
best reserved for small hernias. Examples include 
recurrent umbilical or epigastric hernias, hernias 
involving only a few cm of a midline incision, or 
laparoscopic port site hernias.  
● Larger midline incisional hernias, up to about 
5cm wide, can be repaired with the Underlay 
(Retro-Rectus) Technique; the fascial edges can 
usually be drawn to the midline without 
component separation, and the closure will be 
relatively secure when reinforced by mesh.  
● Midline incisional hernias that are wider than 
about 5cm are unlikely to close, and stay closed, 
with the Retro-Rectus technique alone. The 
hernia 
repair 
described 
in 
the 
Anterior 
Components Separation chapter is the best one 
for these. If no contraindication to mesh 
placement exists, this should be done as well.  
 
Approach to Abdominal Incisional Hernias 
Richard Davis 
 
 
OPEN MANUAL OF SURGERY IN RESOURCE-LIMITED SETTINGS 
www.vumc.org/global-surgical-atlas  
This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License  
 
The surgeon should be prepared for situations 
where a large hernia exists and a mesh cannot be 
placed. These might be anticipated, as when an 
incisional hernia or fascial dehiscence coexists with 
an enterocutaneous fistula or intra-abdominal 
abscess. Or they may be unplanned, such as bowel 
injury and spillage of succus during elective or 
emergency incisional hernia repair. The surgeon 
must have a well-rehearsed “Plan B” at the ready. 
Options include temporary abdominal closure 
(discussed elsewhere in this Atlas,) closure of the 
skin only, or components separation repair.  
● In some cases the best approach is closure of skin 
and subcutaneous tissue only, leaving the hernia 
repair for a later time. This is the best approach 
when gross infection is present; likely the 
primary goal of the surgery was to deal with the 
source of infection or contamination. If this goal 
has been accomplished, there is no shame in 
leaving a complex hernia repair operation for a 
time when it will be safer and more likely to 
succeed.  
● In other cases, “Plan B” will include a complete 
tissue repair of the hernia using the Anterior 
Components Separation technique described in 
this section. This approach is most suitable for 
elective hernia repair in which there is no 
infection, but an inadvertent enterotomy has been 
made and repaired, or a clean-contaminated 
procedure was done.  
 
If one is faced with a large incisional hernia 
and gross contamination or infection, in no case 
should one attempt to pull the fascia together under 
tension and “hope for the best.” This will invariably 
lead to wound dehiscence, which puts the patient at 
risk for evisceration, incarceration of bowel in the 
defect, or damage to the fascia, which will make 
future repairs more difficult. 
 
 
 
 
 
 
 
 
 
 
 
Richard Davis, MD FACS FCS(ECSA) 
AIC Kijabe Hospital 
Kenya 
 
January 2022 
 
Resource-Rich Settings 
These mesh products allow the surgeon to break some of 
the rules that apply to plain polypropylene mesh. They 
are much more expensive, however.  
• 
Polytetrafluoroethylene (PTFE, Gore-Tex®) mesh is 
smooth enough that it can be placed in contact with 
bowel without consequence. Mesh intended for intra-
abdominal use may have one smooth and one rough 
side; the rough side is meant to be placed against the 
abdominal wall and allow tissue ingrowth.  
• 
Polypropylene coated in a biologic membrane, such 
as porcine dermal extracellular matrix, can be placed 
in direct contact with bowel. Often these will also be 
side-specific, with one rough side more likely to 
promote ingrowth into the abdominal wall.  
• 
Absorbable mesh, such as Polyglycolic acid 
(Vicryl®) can be placed in the presence of 
contamination, though it will break down quickly in 
the presence of infection. This material is not useful 
in repairing any abdominal wall hernias.  
• 
Acellular dermal matrix mesh is an animal collagen 
matrix that has had all cellular material removed. 
This mesh can be used in any position; it is often 
used as an “inlay” material to bridge a defect 
between two edges of fascia in the presence of 
infection. This mesh will always break down 
eventually, so if used to bridge a defect it will lead to 
recurrence of the hernia. It is most often used to “bail 
out” of a situation where a hernia coexists with 
contamination or infection.  
 
