ISS Calculator - Anatomical Trauma Score 1-75

The ISS calculator turns the highest Abbreviated Injury Scale grade in each of the six body regions into the 1 to 75 Injury Severity Score from the 1974 Baker paper. It squares the three highest grades from different regions and returns a severity band for trauma triage.

• • Trauma triage review: An emergency physician triaging a multi-injury patient and needing a structured anatomical summary.
• • Trauma registry entry: A registrar entering a multi-region injury case into a trauma registry and checking the squared sum.
• • Teaching rounds: A resident learning how the six ISS body regions combine into a single triage score.
• • Outcome research grouping: An investigator grouping trauma cases by ISS band for outcome research.

The ISS is the most widely used anatomical score for patients with multiple injuries, often paired with the Revised Trauma Score in research.

When the case is being reviewed for ICU triage or research entry, the Injury Severity Score sits naturally alongside the Apache II Calculator because both scores record admission severity in a single structured number.

The calculator reads the highest AIS grade from each of the six ISS body regions, picks the three largest grades from different regions, squares each one, and adds the three squares. A rule sets the total to 75 if any region reaches AIS 6, or if three regions each reach AIS 5.

• a, b, c: The three highest AIS grades from three different body regions, sorted from largest to smallest.
• Six body regions: Head or neck, face, chest, abdomen or pelvic contents, extremities or pelvic girdle, and external.
• AIS grade: The Abbreviated Injury Scale grade of the worst injury in a region, from 0 (no injury) to 6 (maximal, untreatable).
• AIS 6 fatal-injury rule: If any single region reaches AIS 6, the total is set to 75, regardless of the squared sum.
• Three regions at AIS 5 rule: If three or more regions each reach AIS 5, the total is set to 75, because 25 + 25 + 25 already sums to 75.

Squaring a small grade leaves it small and squaring a large grade makes it dominate the total, so a single severe injury moves the score more than several minor ones.

According to Baker et al. 1974 in J Trauma, the total is the sum of the squares of the highest AIS grade from each of the three most severely injured of six body regions, with an automatic cap of 75 when any single injury is AIS 6.

The AAAM, publisher of the AIS dictionary on which the ISS depends, defines the same six body regions and 0 to 6 severity scale that this calculator uses, so the AIS-based tally stays consistent with the dictionary.

A trauma case that ends in the operating room runs through a post-anesthesia review, and the Aldrete Score Calculator returns the five 0-2 criteria the PACU uses to clear the patient, mirroring the structured tally the ISS applies to anatomic regions.

Four concepts drive the result.

The ISS is an anatomical score, not a physiologic one. The Revised Trauma Score or the APACHE II score are often used alongside it in research.

The New Injury Severity Score (NISS) squares the three worst injuries regardless of body region. A research group that wants to capture injuries clustered in a single region may report both.

After the acute phase, the trauma survivor's recovery is reviewed with a structured ADL tally, and the Barthel Index returns the 10 self-care and mobility items that rehabilitation and discharge planning use, mirroring the checklist-style approach the ISS applies to anatomic regions.

Treat the calculator as a structured review of the AIS dictionary. For each body region, pick the highest grade from imaging and operative findings.

1. 1 Gather the AIS grades: Pull the radiology report, operative note, and discharge summary. For each of the six ISS body regions, identify the worst injury and grade it 0 to 6.
2. 2 Enter the six region grades: Pick the head or neck, face, chest, abdomen or pelvic contents, extremities or pelvic girdle, and external grades from the drop-downs. Use 0 for uninjured regions.
3. 3 Read the top-three squares: Check the top three AIS line and the squared sum breakdown to confirm the three largest regional grades were picked.
4. 4 Read the severity band: Add the total to the chart note with the severity band. Use the band to discuss trauma triage or research grouping.
5. 5 Pair with a physiologic score: When the case is reviewed for research or registry entry, pair the ISS with the Revised Trauma Score or the APACHE II score.

A 35-year-old with a flail chest, a grade 4 splenic laceration, and a closed femur fracture has chest AIS 4, abdomen AIS 3, and extremities AIS 3, giving a total of 34 in the severe band.

Because contrast imaging and aminoglycoside antibiotics both depend on kidney function, GFR Calculator supports the renal review that the trauma team usually runs before finalising the contrast CT and the antibiotic plan.

An ISS review can be done in the chart with a pen, but a calculator makes the squared sum consistent, traceable, and easier to defend.

• • Six-region structured review: A single form walks through the six ISS body regions, which keeps the entry consistent across registrars and reviewers.
• • Automatic top-three selection: The calculator picks the three largest AIS grades from different regions, so the user does not have to sort the six values by hand.
• • Transparent squared sum: Each contribution and the running total are visible, so a chart reviewer can verify the score without re-deriving the constant squares on paper.
• • Built-in AIS 6 fatal-injury rule: The calculator sets the total to 75 automatically when any region is graded AIS 6, matching the published cap.
• • Severity band for research: The calculator returns the minor, moderate, serious, severe, critical, or unsurvivable band, the unit most often used for trauma registry reports.

The ISS was designed to make trauma severity easier to discuss across hospitals and registries, and the result is most useful when paired with the reasoning the trauma team would use without the calculator.

Several things can move the score up or down. The biggest ones sit inside the AIS grades themselves.

• • The ISS is an anatomical score and does not measure blood pressure, heart rate, consciousness, or organ dysfunction. Pair it with the Revised Trauma Score or the APACHE II score for a fuller picture.
• • The score was derived in the 1970s. Modern trauma care has shifted the survival curve, so a research group should not interpret an ISS band as a fixed mortality probability without context.

The calculator intentionally stops before the trauma decision. The squared total, severity band, and top-three breakdown are record-organizing aids.

Pair the ISS with a physiologic score for any research or registry entry, and keep the AIS dictionary version in the chart note.

According to the CDC's Web-based Injury Statistics Query and Reporting System (WISQARS), the Injury Severity Score is the standard anatomic severity metric used to summarize nonfatal injury-related hospital emergency department visits and trauma deaths in the US.

Trauma patients on anticoagulation or with active bleeding need a paired coagulopathy review, and the Fresh Frozen Plasma Dose Calculator returns the mL per kg volume and FFP bag count the trauma team uses to reverse the coagulopathy the ISS only describes anatomically.