What is the recommended frequency for blood work after a needle stick exposure in an unvaccinated adult?

Blood Work Frequency After Needlestick Exposure in Unvaccinated Adults

For an unvaccinated adult after needlestick exposure, blood work should be performed at baseline (immediately), 6 weeks, 3 months, and 6 months post-exposure for HIV, with additional testing at 4-6 weeks and 4-6 months for hepatitis C. 1, 2, 3

Immediate Baseline Testing (Within Hours)

• Perform baseline testing immediately for the exposed healthcare worker, including HIV antibody, hepatitis B serology (HBsAg and anti-HBc), hepatitis C antibody (anti-HCV), and alanine aminotransferase (ALT) 1, 3
• Test the source patient as soon as possible for HIV antibody, hepatitis B surface antigen (HBsAg), and hepatitis C antibody to guide prophylaxis decisions 3
• Pregnancy testing should be offered to all women of childbearing age whose pregnancy status is unknown 3

HIV Testing Schedule

• HIV antibody testing must be performed at baseline, 6 weeks, 3 months, and 6 months post-exposure 1, 2, 3
• Additional HIV testing should be conducted immediately if any illness compatible with acute retroviral syndrome occurs during the follow-up period 3
• Rapid HIV testing can be used to expedite decision-making about post-exposure prophylaxis, but do not delay the first PEP dose while waiting for results 3, 4

Hepatitis C Testing Schedule

• For hepatitis C exposure, perform baseline anti-HCV and ALT testing, then repeat at 4-6 weeks and 4-6 months post-exposure 1, 2, 3
• HCV RNA testing at 4-6 weeks is recommended if earlier diagnosis of HCV infection is desired 3
• Repeatedly reactive anti-HCV enzyme immunoassays should be confirmed with supplemental tests 3
• The average risk of HCV transmission is approximately 1.8% (range 0-7%) per percutaneous exposure 2, 5

Hepatitis B Testing Schedule

• For unvaccinated individuals who receive the hepatitis B vaccine series after exposure, perform anti-HBs testing 1-2 months after the last vaccine dose 1
• This testing should occur 4-6 months after HBIG administration if HBIG was given, as anti-HBs response to vaccine cannot be accurately determined if HBIG was received in the previous 3-4 months 1, 3
• The risk of HBV transmission without prophylaxis may exceed 30% after exposure to HBeAg-positive blood, making this the highest transmission risk among bloodborne pathogens 1, 2

Monitoring for Those Receiving Post-Exposure Prophylaxis

• Healthcare workers taking antiretroviral PEP for HIV exposure require monitoring for adverse effects through baseline testing and follow-up testing every 2 weeks 3
• Exposed persons taking PEP should be evaluated within 72 hours after exposure and monitored for drug toxicity for at least 2 weeks 3
• Complete blood count and renal/hepatic function tests should be performed if post-exposure prophylaxis is used 3

Critical Timing Considerations

• The entire follow-up period extends to 6 months post-exposure, as this is when final HIV testing occurs and represents the outer window for seroconversion 2, 3
• Document the exact time of injury immediately, as timing is critical for determining PEP eligibility—HIV PEP must be started within 72 hours, ideally within 1 hour 2, 4
• For unvaccinated individuals exposed to HBsAg-positive blood, HBIG should be administered as soon as possible, ideally within 24 hours 1, 2

Common Pitfalls to Avoid

• Do not fail to establish a system that encourages exposed healthcare workers to return for all scheduled follow-up tests, as inadequate follow-up testing is a major gap in post-exposure management 3
• Do not test discarded needles or syringes for virus contamination, as this is not recommended and results are unreliable 3, 4
• Do not delay baseline testing while waiting to determine source patient status—begin testing immediately 3
• Ensure proper documentation of all test results while maintaining confidentiality of both the source patient and exposed worker 3