Anesthesia can be accomplished by administering a dorsal penile nerve block, with or without a ring block. The penis is innervated by the left and right dorsal nerves; these are branches of the pudendal nerves. The dorsal penile nerve is blocked by injecting a local anesthetic solution deep to Buck’s fascia where the nerves emerge from under the pubic bone. The patient is then placed in the supine position. After preparation of the skin, two injection sites are identified over the inferior edge of the pubic bone at approximately 10 o’clock and 2 o’clock relative to the base of the penis. A 27-gauge, 1.5-in needle is inserted, directed ventrally, until the pubic bone is contacted. The needle is “walked” caudad off the pubis and through Buck’s fascia. After aspiration, 5 mL of local anesthetic is injected at each site. A mixture of equal volumes of 0.5 percent bupivacaine (Marcaine) and 1 or 2 percent lidocaine (Xylocaine) without epinephrine provides rapid onset of anesthesia of suitable duration for circumcision.
As an option, to guarantee adequate anesthesia to the ventral surface and frenulum, a ring block can also be performed. A ring block is a circumferential subcutaneous injection at the base of the penile shaft using a 26- or 27-gauge needle and approximately 10 mL of the anesthetic solution mentioned previously. If the ring block is used in addition to the dorsal nerve block, lidocaine toxicity can be a concern, since a total of 200 mg might be used if 10 mL of 2 percent lidocaine is administered. According to the 1998 Physicians’ Desk Reference, the maximum recommended dose of lidocaine without epinephrine is 4.5 mg per kg or approximately 300 mg, although for safety’s sake, 200 mg is a better maximum total dose.
Potential complications are rare and include hematoma formation and intravascular injection of local anesthetic. Use of an anxiolytic agent may also be considered. Diazepam (Valium), 5 mg given orally one hour before the procedure, is effective. A eutectic mixture of local anesthetics (e.g., EMLA cream) applied to the skin at the base of the penis 30 to 60 minutes before the injections may decrease the pain associated with the needle sticks.