Paracervical Block: Techniques and Considerations

Overview

• Paracervical block is a technique used for various office gynecological procedures, such as cervical biopsies and LEEP procedures.
• Purpose: To introduce an anesthetic near the base of the uterus to block pain fibers.
• Medications Used: Primarily lidocaine (with or without epinephrine) and marcaine.

Medications

• Lidocaine

  • Rapid onset of action
  • Effects wear off quickly
  • Often combined with epinephrine to constrict blood vessels and prolong effect

• Marcaine

  • Long-acting anesthetic
  • Slower onset of action
  • Combined with lidocaine for both rapid and prolonged effects

Nerve Supply

• Nerves to the uterus are formed by:

  • Continuation of the hypogastric plexus
  • Sacral sympathetic efferent fibers from the second, third, and fourth sacral nerves
  • Filaments from the first two sacral ganglia

• Pain Sensation Pathway: Sensory pathways down the lateral and posterior portions of the cervix, into the area of the cardinal and uterosacral nerves.

Technique

• Basic Four Quadrant Technique:

  • Visualize the cervix
  • Grasp anterior lip with a tenaculum
  • Inject anesthetic at positions: 2, 4, 8, and 10 o’clock in submucosal region
  • Aspirate syringe to avoid intravascular injection
  • Anesthetic dissipates into adjacent tissue

• Step-by-Step:

  1. Pre-mix medications
  2. Inject initial dose at 12 o'clock (for tenaculum placement)
  3. Inject small wheals at 3, 9, 5, and 7 o'clock submucosally
  4. Aspirate to avoid intravascular administration
  5. Administer a deeper dose at the same positions
  6. Remove tenaculum, speculum, and patient from lithotomy position after completion
  7. Allow patient to rest for 5 minutes

Considerations

• Cardiovascular Effects
  • Calculating cardiotoxic concentration is vital
  • Caution against introducing anesthetics into the vascular system
  • Aspiration before injection helps avoid intravascular entry
• Potential Side Effects
  • Changes in blood pressure and heart rate, especially with lidocaine and epinephrine
  • Vagal response: May cause a decrease in blood pressure and pulse rate
  • Preparation: Have resuscitation equipment and techniques ready in the office
• Technique Variability: Tailor the exact technique based on patient characteristics and planned intervention

Conclusion

• Paracervical block is a versatile and commonly used anesthetic technique in gynecology.
• Proper medication administration and awareness of cardiovascular effects are crucial for patient safety.
• Individualize technique based on patient needs and procedural demands.