What are the recommendations for local anesthesia in pregnant patients?

From the Guidelines

Local anesthesia is generally safe for pregnant patients when used appropriately, with lidocaine being the preferred local anesthetic during pregnancy, as evidenced by its classification as a pregnancy category B medication by the US Food and Drug Administration 1.

Key Considerations

• The use of local anesthesia in pregnant patients should be guided by the principle of using the minimum effective dose to minimize potential risks to the fetus.
• Lidocaine, with or without epinephrine, is considered safe for use in pregnant patients, with a maximum recommended dose of 4.4 mg/kg 1.
• Epinephrine-containing anesthetics can be used safely in pregnant patients, as the small amounts used in procedures do not significantly affect uterine blood flow.
• When administering local anesthesia to pregnant patients, it's essential to aspirate before injection to avoid intravascular administration and position the patient properly to prevent supine hypotensive syndrome.

Recommendations for Use

• The second trimester is generally considered the safest time for elective procedures requiring local anesthesia, though emergency treatment can be performed at any stage of pregnancy 1.
• Topical lidocaine is safe for use on pregnant or nursing women, but there is insufficient evidence to recommend use of other topical anesthetics.
• Elective procedures and those not of urgent medical necessity requiring topical lidocaine in pregnant women should be postponed until after delivery.
• Procedures of urgent medical necessity should be delayed until at least the second trimester when possible.

Administration Guidelines

• Use the minimum effective dose of local anesthesia to minimize potential risks to the fetus.
• Aspirate before injection to avoid intravascular administration.
• Position the patient properly, slightly tilted to the left side, especially in the third trimester, to prevent supine hypotensive syndrome.
• Consider consulting with the patient’s obstetrician if there are any doubts about the use of local anesthesia during pregnancy.

From the FDA Drug Label

Pregnancy: Teratogenic Effects: Pregnancy Category C: Animal reproduction studies have not been conducted with this solution It is also not known whether this solution can cause fetal harm when administered to a pregnant woman or can effect reproductive capacity. This solution should be given to a pregnant woman only if clearly needed.

Use of Mepivacaine in Pregnant Women: Mepivacaine should be used with caution in pregnant women. The drug label indicates that animal reproduction studies have not been conducted, and it is not known whether the solution can cause fetal harm or affect reproductive capacity.

• Key Considerations:
  • Mepivacaine is classified as Pregnancy Category C.
  • The solution should only be given to a pregnant woman if clearly needed.
  • Caution should be exercised when administering the solution to pregnant women due to the lack of available data on its effects on the fetus or reproductive capacity 2.

From the Research

Local Anesthesia for Pregnant Patients

• Local anesthesia is a crucial aspect of dental treatment, especially for pregnant women who are more vulnerable to oral diseases such as caries, gingivitis, and pyogenic granuloma 3.
• The use of local anesthesia in pregnant patients is considered safe, with 2% lidocaine with 1:200,000 epinephrine being the recommended anesthetic agent due to its balance of safety and efficacy 3.
• However, maternal and fetal considerations must be taken into account, including the use of semi-supine position, blood pressure monitoring, and reassurance for high-risk mothers to reduce the risk of transient changes in blood pressure, hypoxemia, and hypoglycemia 3.

Pharmacology of Local Anesthetics

• Local anesthetics can be categorized into amino-esters (e.g., procaine, chloroprocaine) and amino-amides (e.g., lidocaine, mepivacaine, prilocaine) based on their chemical structure 4.
• The pharmacokinetics of local anesthetics involve the rate of uptake, tissue redistribution, metabolism, and excretion, with the rate of vascular absorption being influenced by the site of injection, dosage, and inclusion of a vasoconstrictor 4.
• Different local anesthetics have varying durations of action, with lidocaine and mepivacaine being intermediate-acting and bupivacaine being long-acting 4.

Safety and Efficacy of Local Anesthetics in Pregnancy

• The available literature suggests that local anesthetics are safe for use in pregnant and postpartum patients, with no significant risks to the mother or fetus 5.
• Liposomal formulations of local anesthetics such as prilocaine, lidocaine, and mepivacaine have been shown to prolong analgesic duration and provide effective drug delivery systems 6.
• A study on the allergenicity of local anesthetics found no evidence of type-1 allergy to procaine, lidocaine, or mepivacaine, suggesting that these agents can be used safely in therapy and short-track surgery 7.