Emergency Medicine · Infectious Disease · Occupational medicine

HIV Needle Stick Risk Assessment Stratification Protocol (RASP) calculator

Enter the published formula inputs below to calculate and interpret this score.

Clinical inputs

Source status

Step A for an average Canadian community: acute AIDS illness 1, asymptomatic known HIV 10, unknown HIV in a high-risk situation 100, other unknown HIV 1000.

Inoculum

Route

Volume modifier

Step D multiplies the basic risk: massive such as transfusion 100, measurable over 1 mL 10, large-bore hollow needle 5, small-bore hollow needle 3, trace surface only 1.

Result

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Primary source

Vertesi L. Risk Assessment Stratification Protocol (RASP) to help patients decide on the use of postexposure prophylaxis for HIV exposure. CJEM. DOI: 10.1017/S1481803500008113. PMID: 17659153. Figure 1: Z = A × B × C and basic risk = 1/Z. Total risk = basic risk × D. The score returned here is the denominator N of that total risk, so total risk = 1/N and N = (A × B × C) / D. Step A: acute AIDS illness 1, asymptomatic known HIV 10, unknown HIV in a high-risk situation 100, other unknown HIV 1000. Step B: fresh blood 1, body fluids at risk such as semen 10, dried old blood 100, low-risk secretions 1000. Step C: intravenous 1, deep intramuscular 10, deep transcutaneous with visible bleeding 100, superficial transcutaneous with no visible bleeding 200, mucosal contact only 500, intact skin 1000. Step D: massive such as transfusion 100, measurable over 1 mL 10, moderate large-bore hollow needle 5, small small-bore hollow needle 3, trace surface only 1. Table 2: risk level under 1/1000 is definitely indicated, 1/1000 through 1/10,000 is recommended but optional, 1/10,001 through 1/100,000 is optional but not recommended, and over 1/100,000 is not indicated. Example 1 uses A 10, B 1, C 100, and D 3, so N = 333.3. Example 2 uses A 1000, B 100, C 200, and D 5, so N = 4,000,000. (2003)

Scope: People with a possible HIV exposure in an average Canadian community, the setting used to set the Figure 1 values. The values are the ones printed for that setting.

Last reviewed 2026-10-17

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Professional use only

For qualified clinicians. Independently verify inputs, calculations, source guidance, and applicability before any clinical action. This calculator does not replace clinical judgment.

Source: Vertesi L. Risk Assessment Stratification Protocol (RASP) to help patients decide on the use of postexposure prophylaxis for HIV exposure. CJEM. DOI: 10.1017/S1481803500008113. PMID: 17659153. Figure 1: Z = A × B × C and basic risk = 1/Z. Total risk = basic risk × D. The score returned here is the denominator N of that total risk, so total risk = 1/N and N = (A × B × C) / D. Step A: acute AIDS illness 1, asymptomatic known HIV 10, unknown HIV in a high-risk situation 100, other unknown HIV 1000. Step B: fresh blood 1, body fluids at risk such as semen 10, dried old blood 100, low-risk secretions 1000. Step C: intravenous 1, deep intramuscular 10, deep transcutaneous with visible bleeding 100, superficial transcutaneous with no visible bleeding 200, mucosal contact only 500, intact skin 1000. Step D: massive such as transfusion 100, measurable over 1 mL 10, moderate large-bore hollow needle 5, small small-bore hollow needle 3, trace surface only 1. Table 2: risk level under 1/1000 is definitely indicated, 1/1000 through 1/10,000 is recommended but optional, 1/10,001 through 1/100,000 is optional but not recommended, and over 1/100,000 is not indicated. Example 1 uses A 10, B 1, C 100, and D 3, so N = 333.3. Example 2 uses A 1000, B 100, C 200, and D 5, so N = 4,000,000. (2003)

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Clinical inputs

Source status
Inoculum
Route
Volume modifier

Primary source

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