The EHS Classification of Abdominal Wall Hernias

The EHS classification is the common language for describing abdominal wall hernias: it distinguishes primary from incisional hernias, divides the abdomen into five midline zones (M1–M5) and four lateral zones (L1–L4) and grades defect width (W1 under 4 cm, W2 between 4 and 10 cm, W3 over 10 cm).

Proposed by the European Hernia Society in 2009 (Muysoms et al.) and updated in 2014, the EHS classification was created to make cases comparable across studies and registries: without a shared description of site and size, every figure on recurrence or complications remains hard to interpret. The patient page presents zones and defect types in plain form; here the emphasis is on clinical use.

Primary hernias

For primary midline hernias (epigastric and umbilical) the classification combines site and defect diameter: small under 2 cm, medium between 2 and 4 cm, large over 4 cm. The 2 cm threshold for umbilical hernias has direct practical weight: below it the literature still discusses the role of mesh, above it mesh repair is recommended.

Incisional hernias: the zones

Incisional hernias are located on a grid: five midline zones (M1 subxiphoid, M2 epigastric, M3 periumbilical, M4 hypogastric, M5 suprapubic) and four lateral zones per side (L1 subcostal, L2 transverse/flank, L3 iliac, L4 lumbar). An incisional hernia occupying several zones should be reported with the whole interval: mesh coverage must extend to every declared zone.

Defect width

Width, measured on the transverse axis and ideally confirmed in the operating room, is graded W1 (<4 cm), W2 (4–10 cm) and W3 (≥10 cm). It is the parameter that most guides the technique: in W1 the discussion is between suture and mesh, in W2 mesh is standard, in W3 repair almost always requires tissue advancement (component separation).

How to report it

A wording such as "M2–M4 W3 incisional hernia" communicates in one line the site, the craniocaudal extension and the width: the reader already knows the repair will require a wide pocket and probably a component separation. The classification does not assess the sac content, loss of domain or previous recurrences: these are reported separately, together with the expected field contamination and the choice of mesh plane.