Is aspiration still necessary during intramuscular (IM) injections?

Aspiration During Intramuscular Injection: Current Recommendations

Aspiration during intramuscular (IM) injections is generally no longer recommended as a routine practice for most injection sites, as there are no large blood vessels at the recommended injection sites. 1

Current Evidence and Guidelines

• The Centers for Disease Control and Prevention (CDC) does not support or recommend aspiration during intramuscular injections, stating that "aspiration before injection of vaccines or toxoids is not required because no large blood vessels exist at the recommended injection sites." 2

• A retrospective study found no episodes of blood aspiration in 25,285 immunotherapy injections, and a subsequent prospective study confirmed no blood aspiration in 6,642 immunotherapy injections, suggesting aspiration may be unnecessary. 2

• Despite current guidelines, 74% of registered nurses continue to aspirate during IM injections, though only 3% aspirate for the recommended 5-10 seconds when they do so. 3

Site-Specific Considerations

• Deltoid, ventrogluteal, and vastus lateralis sites: Aspiration is unnecessary at these sites due to the absence of major blood vessels. 4

• Dorsogluteal site: Aspiration is still recommended when using this site due to its proximity to the gluteal artery. 4

• If blood appears during aspiration, the syringe should be removed, discarded in a sharps container, and a new dose prepared for injection at a different site. 2

Practical Implications

• Blood aspiration does occur during IM injections, with 40% of nurses reporting having aspirated blood at least once, most frequently in the dorsal gluteal (15%) and deltoid (12%) sites. 3

• Administering injections faster without aspiration has been shown to be less painful than injecting slowly with aspiration. 4

• The decision to aspirate is often influenced by what healthcare professionals were taught and fear of injecting into a blood vessel rather than current evidence. 4

Special Considerations

• Aspiration may still be warranted when:

  • The medication has significantly different administration rates, doses, or effects when given IM versus IV 3
  • The injection site is near major blood vessels 1
  • Administering medications where intravascular injection could cause serious adverse effects 1

• For subcutaneous injections (such as allergen immunotherapy), pinching and lifting the skin to avoid intramuscular or intravenous injection is recommended. 2

Conclusion

Based on the most recent evidence, routine aspiration during IM injections is unnecessary for most commonly used injection sites (deltoid, ventrogluteal, and vastus lateralis). However, aspiration should still be considered when using the dorsogluteal site or when administering medications where intravascular administration would pose significant risks.