What laboratory tests are required for an 18-month-old child after a needle stick injury with a potentially contaminated needle?

Laboratory Tests Required After Needle Stick Injury in an 18-Month-Old Child

For an 18-month-old child with a dirty needle stick injury, baseline testing should include hepatitis B, hepatitis C, and HIV serologies, with follow-up testing at 6 months post-exposure. 1

Initial Assessment and Testing Protocol

Immediate Laboratory Tests Required:

• Baseline serologies for the child:
  • Hepatitis B surface antigen (HBsAg) and antibody (anti-HBs)
  • Hepatitis C antibody
  • HIV antibody

Source Testing (if needle source is known):

• Attempt to identify the source of the needle if possible
• If source is identifiable, test for:
  • Hepatitis B surface antigen
  • Hepatitis C antibody
  • HIV antibody or rapid HIV test 1

Post-Exposure Prophylaxis Considerations

Hepatitis B Prophylaxis:

• If child is unimmunized against hepatitis B:
  • Administer hepatitis B immunoglobulin (HBIG) 0.06 mL/kg (maximum 5 mL) intramuscularly
  • Begin hepatitis B vaccine series 1
• If child has been previously immunized:
  • Verify immunity status through anti-HBs testing
  • If documented response to vaccination, no treatment needed
  • If no documented response, consider HBIG and vaccine booster

HIV Prophylaxis:

• Consider HIV post-exposure prophylaxis based on risk assessment
• Decision should be made within 24-48 hours of exposure
• Consultation with pediatric infectious disease specialist is recommended 1

Hepatitis C:

• No proven post-exposure prophylaxis exists
• Monitor for potential infection through follow-up testing

Follow-Up Testing

• Repeat serologic testing at 6 months post-exposure:
  • Hepatitis B (HBsAg and anti-HBs)
  • Hepatitis C antibody
  • HIV antibody 1

Risk Assessment

The risk of bloodborne virus transmission from community-acquired needle stick injuries is very low 2. A study of 274 pediatric community-acquired needle stick injuries reported no seroconversions for HIV, HBV, or HCV 2. However, testing is still warranted due to the theoretical risk of transmission.

Important Considerations

• Timing is critical - baseline labs should be drawn as soon as possible after the exposure
• The wound should be washed immediately and thoroughly with soap and water 1
• Documentation of the incident should include details about the needle (appearance, location found, presence of visible blood) 1
• Parental education about the low risk of seroconversion may help reduce anxiety 3

Common Pitfalls to Avoid

• Delaying prophylaxis decisions while waiting for source testing results - initiate prophylaxis based on risk assessment and modify later if needed 1
• Failing to document baseline serologic status - essential for determining if any future positive results represent new infections
• Neglecting follow-up testing - ensure a system is in place to track the child for the recommended 6-month follow-up testing
• Overestimating risk - while testing and prophylaxis are necessary precautions, parents should be counseled that actual transmission risk is very low 2, 3