What are the important labs to order after a used needle stick injury?

Important Laboratory Tests After a Needlestick Injury

After a needlestick injury with a used needle, immediate testing should include HIV antibody, Hepatitis B surface antigen (HBsAg), and Hepatitis C antibody (anti-HCV) tests for both the source patient and the exposed healthcare worker. 1

Initial Testing and Management

Source Patient Testing

• Test the source patient for HIV antibody, HBsAg, and anti-HCV as soon as possible to guide post-exposure management decisions 1
• Consider using rapid testing for HIV to expedite decision-making about post-exposure prophylaxis (PEP) 2
• Do not test discarded needles or syringes for virus contamination as this is not recommended and results are unreliable 2

Exposed Healthcare Worker Testing

• Perform baseline testing for HIV antibody, Hepatitis B serology (including vaccination status), and Hepatitis C antibody 2, 1
• Document immune status for HBV infection by history of hepatitis B vaccination and vaccine response 2
• Pregnancy testing should be offered to all non-pregnant women of childbearing age whose pregnancy status is unknown 2

Follow-up Testing Schedule

HIV Follow-up

• Perform HIV-antibody testing at baseline, 6 weeks, 3 months, and 6 months post-exposure 2, 1
• Conduct additional HIV antibody testing if illness compatible with acute retroviral syndrome occurs 2

Hepatitis B Follow-up

• For those who receive hepatitis B vaccine, perform follow-up anti-HBs testing 1-2 months after the last dose of vaccine 2
• Note that anti-HBs response to vaccine cannot be accurately determined if HBIG (Hepatitis B Immune Globulin) was received in the previous 3-4 months 2

Hepatitis C Follow-up

• Perform baseline and follow-up testing for anti-HCV and alanine aminotransferase (ALT) at 4-6 months after exposure 2, 1
• Consider HCV RNA testing at 4-6 weeks if earlier diagnosis of HCV infection is desired 2
• Confirm repeatedly reactive anti-HCV enzyme immunoassays (EIAs) with supplemental tests 2

Monitoring for Those Receiving PEP

• For healthcare workers taking antiretroviral PEP for HIV exposure, monitor for adverse effects through baseline testing and follow-up testing every 2 weeks 2
• Complete blood count and renal/hepatic function tests should be performed to monitor for drug toxicity if post-exposure prophylaxis is used 1
• Evaluate exposed persons taking PEP within 72 hours after exposure and monitor for drug toxicity for at least 2 weeks 2

Risk Assessment Considerations

• The risk of HIV seroconversion after percutaneous exposure to HIV-infected blood is approximately 0.36% (3.6 per 1,000 exposures) 1, 3
• The risk of HBV transmission without prophylaxis may exceed 30% after exposure to HBeAg-positive blood 1, 3
• Risk factors that increase the likelihood of transmission include:
  • Deep injuries 3
  • Visible blood on the device 3
  • Needle placement in a vein or artery of the source patient 3
  • High viral load in the source patient 3

Documentation and Counseling

• Document all test results and maintain confidentiality of both the source patient and exposed worker 1
• Provide counseling regarding:
  • Risk of transmission 1
  • Precautions to prevent secondary transmission during the follow-up period 2
  • Signs and symptoms of viral infection 1
  • Importance of seeking medical evaluation for any acute illness occurring during follow-up 2

Common Pitfalls to Avoid

• Failing to test the source patient when possible - this information is crucial for risk assessment and management decisions 2
• Delaying or not initiating PEP when indicated - PEP should be started as soon as possible, ideally within hours of exposure 3
• Inadequate follow-up testing - ensure a system is in place to encourage exposed healthcare workers to return for all scheduled follow-up tests 2
• Not documenting the exposure details - comprehensive documentation is essential for proper follow-up and potential workers' compensation claims 1