Scene Size-Up

Category: Patient Assessment Sources: raw/supplemental/patient-assessment-sequence.md, raw/nremt/psychomotor-skills.md Last updated: 2026-04-03

Overview

Scene size-up is the first step in every patient contact and happens before you touch the patient. The goal is to gather situational awareness — identify hazards, understand what happened, and determine what resources you need. If the scene is not safe, do not enter.

Key Points

• BSI/PPE first: Gloves are the absolute minimum. Add eye protection, gown, or mask based on anticipated exposure risk (blood, vomiting, airborne illness).
• Scene safety: Look for hazards before approaching — traffic, violence, downed power lines, structural instability, smoke, hazmat. If the scene becomes unsafe after entry, exit.
• MOI vs NOI: Determine whether the call is trauma (mechanism of injury) or medical (nature of illness). This drives the entire assessment path downstream.
• Number of patients: Count patients before committing resources. One critical patient may need all your attention; three patients may require mutual aid immediately.
• Additional resources: Request before you need them — ALS upgrade, fire, law enforcement, additional units. It is faster to cancel a response than to call for one late.
• C-spine consideration: High-energy MOI (MVC, fall from height, diving, penetrating trauma near spine) triggers manual spinal stabilization immediately.

Assessment Relevance

Scene size-up feeds every decision that follows. MOI vs NOI determines whether you perform a rapid trauma assessment or a focused medical exam in the secondary assessment. Significant MOI triggers spinal precautions and alters your transport priority. Patient count determines triage if MCI criteria are met.

Standard flow into the next step: size-up complete → move to primary-assessment.

Procedures

1. Don BSI/PPE before approaching.
2. Scan the scene from a distance before committing to approach.
3. Identify hazards and mitigate or stage safely.
4. Determine MOI (trauma) or NOI (medical).
5. Count patients visible; look for additional victims.
6. Request additional resources if patient count or acuity warrants.
7. Apply manual c-spine stabilization if MOI suggests spinal injury.

NM Protocol Notes

• NM EMS follows standard scene safety doctrine. In rural San Juan County, common hazards include agricultural equipment, oil field operations, and remote terrain.
• NM law requires EMS providers to stage and wait for law enforcement clearance on scenes involving violence or potential weapons.
• Hazmat incidents: stage uphill and upwind; NM uses NIMS/ICS command structure.

NREMT Relevance

Scene size-up is the opening step on both the Trauma and Medical patient assessment/management skills sheets. Examiners look for: - Verbalizing BSI/PPE before any patient contact - Verbalizing scene safety assessment - Correctly identifying MOI vs NOI - Verbalizing number of patients - Verbalizing need for additional resources when indicated - Verbalizing c-spine consideration based on MOI

Failure to verbalize BSI is a critical failure on many skill stations. Say it out loud, every time.

Related

• primary-assessment — next step after size-up is complete
• secondary-assessment — MOI vs NOI decision made here drives secondary exam path
• spinal-immobilization-supine — initiated based on MOI identified during size-up
• spinal-immobilization-seated — initiated based on MOI identified during size-up
• bleeding-control-shock — major bleeding identified on scene entry is addressed in primary assessment

Sources

• raw/supplemental/patient-assessment-sequence.md — Section 1: Scene Size-Up
• raw/nremt/psychomotor-skills.md — Patient Assessment/Management (Trauma and Medical)