Dorsal Penile Nerve Block

Local anesthesia ^[1] of the penis is used as preparation to perform various procedures, including release of paraphimosis, dorsal slit of the foreskin, circumcision, ^{[2, 3, 4]} and repair of penile lacerations. The penis is innervated by the pudendal nerve (S2-S4). This nerve eventually divides into the right and left dorsal nerves of the penis that pass under the pubis symphysis to travel just below the Buck fascia to supply the sensory innervation to the penis. See relevant anatomy in the image below.

The penile shaft is composed of 3 erectile columns, the 2 corpora cavernosa and the corpus spongiosum, as well as the columns' enveloping fascial layers, nerves, lymphatics, and blood vessels, all covered by skin. The 2 suspensory ligaments, composed of primarily elastic fibers, support the penis at its base. For more information about the relevant anatomy, see Penis Anatomy.

The use of parenteral analgesia with or without sedation is recommended before the application of local penile anesthesia.

Indications for anesthesia of the penis include the following:

• Dorsal slit of the foreskin

• Phimosis reduction

• Paraphimosis reduction

• Repair of penile lacerations

• Release of penile skin entrapped in zippers

Contraindications for anesthesia of the penis include the following:

• Suspected testicular torsion

• Skin infection at the site of injection

The use of topical anesthetic cream is recommended for all penile procedures. ^[5]

Eutectic mixture of local anesthetics (EMLA) cream is commonly used. ^[6]

The cream should be left on the skin area for at least 45 minutes before the planned procedure.

For more information, see Anesthesia, Topical.

Patients who do not achieve adequate anesthesia with the topical application of an anesthetic cream should receive either a local anesthetic infiltration or a penile block. ^[3]

The following equipment is needed:

• Povidone iodine solution (eg, Betadine)

• 4 x 4 gauze

• Local anesthetic solution without epinephrine

• Syringe, 5 mL

• Needles, 16 and 27 gauge (ga)

The patient should be in the supine position with his genitalia exposed.

Patient preparation

After obtaining informed consent from the patient, the healthcare professional should follow these steps:

• Have the patient lay supine on a gurney with his genitalia exposed.

• Clean gross debris.

• Apply a generous amount of povidone iodine solution to the penis and scrotum.

  • Soak a 4 x 4 gauze pad in povidone iodine solution.

  • Clean the glans and shaft in a circular motion.

  • Repeat this step at least 2 more times.

• Create a sterile field by placing drapes between the scrotum and the shaft, above the shaft, and on either side.

• Administer parenteral analgesia with or without sedation.

Local infiltration – Penile lacerations

See the list below:

• Use a 27-ga needle to raise a skin wheal.

• Insert the needle subcutaneously through the skin wheal to infiltrate the local anesthetic on both sides of the skin laceration.

Local infiltration – Dorsal slit of foreskin

See the list below:

• Use a 27-ga needle to raise a skin wheal at the base of the foreskin in the dorsal 12-o'clock position.

• Insert the needle subcutaneously through the skin wheal and advance it distally while infiltrating local anesthetic all the way to the tip of the foreskin (see image below).

  Local infiltration – Dorsal slit of the foreskin.

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Local infiltration – Circumferential penile block

See the list below:

• This technique can be used for anesthesia of complex penile skin lacerations or before attempting to manually reduce paraphimosis.

• Use a 27-ga needle to circumferentially infiltrate local anesthetic around the penis (see image below).

  Local infiltration – Circumferential penile block.

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Penile block

See the list below:

• The right and left dorsal penile nerves should be blocked as proximally to the base of the penis as possible.

• Use a 27-ga needle to raise skin wheals at the 2- and 10-o'clock positions (see image below).

  Insertion sites at the 10- and 2-o'clock positions.

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• Slowly insert the needle through the center of each skin wheal.

• The needle should be directed toward the center of the shaft, to a depth of about 0.5 cm or until loss of resistance is felt to suggest that the tip of the needle is within the Buck fascia.

• Aspirate to ensure that the needle is not in a blood vessel, and slowly inject about 2 mL of local anesthetic on each side. In neonates and children (< 10 kg), inject 0.2-0.4 mL of lidocaine 1% on each side (10 and 2 o'clock) using a 30-g needle. No more than 4.5 mg/kg should be injected. ^[7]

• An alternative method is to inject 2 mL of local anesthetic on either side of the midline, avoiding injecting into the superficial dorsal penile vein (see image below).

  Penile block - Paramidline technique.

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Only use anesthetic solutions without  epinephrine when administering injectable anesthesia to the penis. ^[8] Injected anesthetic solutions that contain epinephrine have been associated with penile ischemia and necrosis.

Complications may include the following:

• Bleeding and hematomas: Most penile bleeding can be easily controlled with direct pressure.

• Failure to achieve adequate anesthesia: A different block should be attempted as long as the toxic dosage of the anesthetic was not exceeded. ^[9]

• Skin sloughing: This complication is more common with distal shaft/glans injections and when anesthetic that contains epinephrine is used.

• Infection: The injection site can become infected, but this is rare. ^[10] A prophylactic antibiotic is not recommended; rather, the patient should be given detailed return precautions.