D-COMPASS – educational calculator

Input data

1. Patient and safety context

Age

BMI

ASA

Wound class

Suspected mesh infection

2. D — Defect geometry, position, and content

Hernia type

Location

Previous recurrences

Defect width [cm]

Defect length [cm]

Number of defects

Total scar / weakened-zone length [cm]Used for incisional or recurrent reconstruction length.

Full reconstruction-zone width [cm]Optional. Use when the weakened area is wider than the fascial opening.

Full reconstruction-zone length [cm]Optional. Overrides defect length when larger.

Overlap rule used by the calculator: primary defect ≤4 cm → 3 cm; any incisional/recurrent defect or primary defect >4 cm up to 12 cm → 5 cm; defect width >12 cm → 7 cm. A primary defect between 4 and 5 cm therefore belongs to the 5 cm category.

Transverse position relative to the midline and semilunar lines

Use a signed centre offset: right = positive, left = negative. Distances from defect edges to semilunar lines may be entered directly or calculated from linea alba and rectus widths. Negative values mean the defect crosses the semilunar line.

Defect centre offset from midline [cm]

Linea alba width [cm]

Left rectus width [cm]

Right rectus width [cm]

Left defect edge → left semilunar line [cm]Optional direct measurement; overrides calculated value.

Right defect edge → right semilunar line [cm]Optional direct measurement; overrides calculated value.

Sac, deformity, reduction, and loss of domain

Sac size

External wall deformity

Reduction of sac contents

Loss of domain [%]

Abdominal capacity after reduction

3. C — Closure feasibility

Anticipated fascial closure after reduction

Posterior layer closure

P — Plane / Position is calculated automatically.
No preperitoneal or retrorectus pocket measurements are required. The calculator derives lateral space from defect position, linea alba, rectus widths, and semilunar-line distances, then applies location-specific cranial and caudal extension rules. For midline defects, the standard preperitoneal option is limited to a complete calculated mesh width of 10 cm.

4. A — External reconstruction requirements

Skin / soft-tissue excess

Abdominal wall / soft-tissue loss

Abdominal wall plasty or tissue resection is required

5. S — Expected implant stability

Will the mesh lie completely flat?

Will the mesh be enclosed in a closed plane?

Risk of displacement

Clear

Editable thresholds are in $RULES. The main logic is in calculateDCompass(). Plane selection is automatic: midline preperitoneal candidacy requires a complete calculated mesh width ≤10 cm; otherwise the calculator proceeds to retrorectus capacity, unilateral TAR, or bilateral TAR from side-specific anatomy.