Incisional Hernia: The Complete Guide

What is an incisional hernia?

An incisional hernia occurs at a previous surgical incision when the fascial layer fails to heal fully or weakens over time. Most appear within the first 2–3 years after surgery, though they can develop much later. It is one of the main types described in the complete hernia guide.

How common is it?

• After 10–20% of midline laparotomies.
• 30% or more in high-risk patients (obesity, abdominal aortic aneurysm, wound infection).
• Also at laparoscopic port sites, after caesarean section, kidney, liver and transplant surgery.

Risk factors

Patient factors: obesity (the most important modifiable factor), smoking, diabetes, malnutrition, steroids and immunosuppression, aortic aneurysm and collagen disorders, chronic cough, constipation.

Surgical factors: wound infection (one of the strongest), closure technique — the STITCH trial showed that "small bites" closure significantly reduces incisional hernia — emergency surgery, re-laparotomy and midline incisions.

Symptoms

• A bulge in the old scar that grows with standing and coughing.
• Pain, pulling and difficulty lifting.
• Skin problems over large hernias.
• Indigestion, constipation or recurrent colic from partial bowel trapping.
• Impaired breathing and posture in giant hernias.

Diagnosis and classification

• CT is usually needed before surgery to map the number and size of defects and the volume outside the abdomen.
• EHS classification: midline (M1–M5) or lateral (L1–L4), width W1 (<4 cm), W2 (4–10 cm), W3 (>10 cm).
• Loss of domain: when much of the bowel lives outside the abdomen, special preparation is needed.

Treatment

Incisional hernias do not disappear and enlarge over time; surgery is curative. Small asymptomatic hernias in high-risk patients may be observed.

Prehabilitation

• Stop smoking for at least 4–6 weeks.
• Lose weight — many surgeons prefer BMI below 35 for elective repair; bariatric surgery may come first.
• Optimise diabetes, nutrition, breathing exercises and walking.
• For giant hernias: Botox injection into the lateral abdominal muscles 4–6 weeks before surgery and/or progressive pneumoperitoneum.

Repair techniques

Key principles: restore the midline and abdominal wall function, use a large mesh with adequate overlap, prefer sublay placement, repair all defects along the scar, and use special meshes or staged repair in contaminated fields.

See hernia mesh types and hernia surgery.

Prevention

• Small-bites closure (5 mm × 5 mm).
• Prophylactic mesh in high-risk patients — the PRIMA trial showed it reduces incisional hernia.
• Reduce wound infection; stop smoking and optimise weight and diabetes before any operation.
• Avoid heavy lifting early after abdominal surgery; treat cough and constipation.