What laboratory tests should be ordered after a needlestick injury?

Laboratory Testing After Needlestick Injury

Immediately order baseline testing for both the source patient (if available) and the exposed nurse: HIV antibody, Hepatitis B surface antigen (HBsAg), and Hepatitis C antibody (anti-HCV), with follow-up testing scheduled at 6 weeks, 3 months, and 6 months for HIV, and at 4-6 months for HCV. 1

Immediate Source Patient Testing

Test the source patient as soon as possible for: 1

• HIV antibody (consider rapid testing to expedite PEP decision-making) 1
• Hepatitis B surface antigen (HBsAg) 2, 1
• Hepatitis C antibody (anti-HCV) 2, 1

Critical pitfall to avoid: Do not attempt to test the discarded needle itself for virus contamination—this is unreliable and not recommended by the CDC. 1

Baseline Testing for the Exposed Nurse

Order the following baseline tests immediately: 1

• HIV antibody test 1
• Hepatitis B serology (document vaccination history and vaccine response) 1
• Hepatitis C antibody (anti-HCV) 2, 1
• Alanine aminotransferase (ALT) 2, 1
• Pregnancy test for women of childbearing age whose pregnancy status is unknown 1

Follow-Up Testing Schedule

For HIV Exposure:

• 6 weeks post-exposure: HIV antibody testing 1
• 3 months post-exposure: HIV antibody testing 1
• 6 months post-exposure: Final HIV antibody testing 1
• Additional testing: If acute retroviral syndrome symptoms develop at any time 1

For Hepatitis C Exposure:

• 4-6 weeks post-exposure: HCV RNA testing for early diagnosis (if desired) 2, 1
• 4-6 months post-exposure: Anti-HCV and ALT testing 2, 1
• Confirmatory testing: Use supplemental tests (such as RIBA) for repeatedly reactive anti-HCV enzyme immunoassays 2, 1

For Hepatitis B Exposure:

• 1-2 months after last vaccine dose: Anti-HBs testing (if vaccine was administered as part of post-exposure management) 1
• Important caveat: Anti-HBs response cannot be accurately determined if HBIG was received in the previous 3-4 months 1

Additional Monitoring if PEP is Initiated

If the nurse receives HIV post-exposure prophylaxis: 1

• Baseline: Complete blood count, renal function tests, hepatic function tests 1
• Every 2 weeks: Monitor for drug toxicity 1
• Within 72 hours: Clinical evaluation after exposure 1

Understanding the Risk Context

The transmission risks help contextualize the urgency of testing: 2

• HIV: Approximately 0.36% risk per percutaneous exposure to infected blood 2
• Hepatitis C: Average 1.8% risk (range 0-7%) per percutaneous exposure 2
• Hepatitis B: May exceed 30% risk without prophylaxis if source is HBeAg-positive 2

Key clinical point: One in five hospitalized patients may be infected with at least one bloodborne pathogen, making systematic testing protocols essential. 3

Documentation and Counseling Requirements

Ensure the following are addressed: 1

• Document all exposure details (date, time, procedure, device type, severity) 1
• Provide counseling on precautions to prevent secondary transmission during follow-up 1
• Emphasize the importance of seeking medical evaluation for any acute illness during the follow-up period 1
• Maintain confidentiality for both source patient and exposed worker 1

Common pitfall: Inadequate follow-up testing occurs frequently. Establish a system to ensure the exposed nurse returns for all scheduled follow-up tests, as complete monitoring is essential for early detection of seroconversion. 1