Nerve block: perianal block

Overview

Perineal innervation.

• Perianal blocks have been shown to be comparable to general anesthesia for in terms of pain control in anal procedures including surgeries
• "Perianal block is a safe, feasible, reliable, and reproducible mode of anesthesia."

Indications

• Rectal foreign body removal
• External hemorrhoid excision
• Rectal prolapse
• Anorectal abscess

Contraindications

• Overlying infection
• Allergy to chosen anesthetic
• Uncooperative patient

Equipment Needed

• 20 cc Syringe with a 27 Gauge Needle
• Spare 18 Gauge Needle (to draw up anesthetic)
• Local Anesthetic (e.g. Lidocaine or Bupivacaine)
• Silk Tape
• Pillow or Blankets
• Packaged, Moist Towelette

Procedure

• Obtain informed consent
• Place the patient in the prone position, placing either a pillow or blankets under their hips for comfort and ideal positioning
• Using tape, separate the patient's buttocks from one another to better visualize the perianal area
• Draw up anesthetic into 20 cc syringe using 18 Gauge Needle
• Ensure that the perianal area is clean by removing debris with moist towelette
• Peripheral to the anal sphincter, choose multiple injection sites that allow for fanning circumferentially around the anus
• Advance 27 Gauge needle into one of these preselected areas
• Aspirate to rule out intravascular placement prior to injecting 3 -5 mL of anesthetic
• Continue to the other preselected areas, fanning the needle circumferentially in order to surround the anal area with local anesthetic

See Also

• Nerve and regional blocks (main)