Anesthesia for Neonatal Circumcision: Physician Knowledge, Training, and Practices
The decision to disregard national guidelines and defer anesthesia and analgesia for infant circumcision may be linked to physician knowledge, experience, and training. Two national surveys examined teaching practices specific to newborn circumcision anesthesia and analgesia in pediatric and family practice and obstetric residency training programs in the United States.[30,31] The first survey found that 26% of the programs did not provide instruction on pain control. The second survey (n 1,778) examined self-reported clinical practices surrounding the use of circumcision anesthesia among pediatricians, family practice physicians, and obstetricians by using a questionnaire. They found that 71% of pediatricians, 56% of family practice physicians, and 25% of obstetricians used anesthesia ( Table 2 ). Of those who chose not to use anesthesia, 54% cited "concern over adverse drug effects," and 44% responded that "the procedure does not warrant anesthesia."
Unfamiliarity with the safety, efficacy, and ease of administration of penile blocks may be a barrier to their use. The 2 most frequently used variations of penile nerve blocks for infant circumcision are the dorsal penile nerve block (DPNB) and the subcutaneous ring block (SQRB). The DPNB was first described in this country in 1978. Several studies have determined that this block is effective in relieving both the stress and pain of circumcision, demonstrating the following[3,4,33,34,35]:
Significantly smaller decreases in transcutaneous oxygen saturation levels
Decreased crying times
Smaller increases in heart rates
Lower elevations in serum cortisol levels
These studies and others have also concluded that the DPNB is safe and without significant complications.[3,32,33,34,36,37,38,39] When complications do occur, they are minor and temporary. They include edema; bleeding from injection sites, which can be controlled with pressure; or small ecchymoses or hematomas at the injection sites. All resolve spontaneously over a few days.[5,6,33]
The SQRB was first described in medical literature in 1987 as a technique to reduce postcircumcision pain in children and adults. The ring block has since been recommended as a safe and effective technique for circumcision.[5,41] One study concluded that compared with any other intervention, the use of SQRB may be the most effective in preventing pain during circumcision. The SQRB provided more complete anesthesia during all phases of circumcision compared with the DPNB and may be technically easier to administer(Fig 2).
Heart rate differences at various surgical stages of circumcision. Reprinted with permission. JAMA, Vol 278, Page 2161, Copyright 1997, American Medical Association.
The efficacy of both these nerve blocks depends on a clear understanding of the anatomy and proper technique. See Figures 3A-C for a review of the relevant anatomy. The anesthetic must be instilled accurately into the appropriate tissue surrounding the 2 dorsal penile nerves that provide sensory innervation to the foreskin, glans, and shaft of the penis. These nerves, located between Buck's fascia and the corpora cavernosa, traverse the dorsal surface of the shaft at approximately 10 and 2 o'clock. At the root of the penis, the nerves lie about 3 to 5 mm beneath the skin. As they progress distally toward the glans, they are more superficially located at 1 to 3 mm beneath the skin. To perform the DPNB, a local anesthetic is injected subcutaneously below Buck's fascia at the 10 and 2 o'clock positions, 0.5 to 1 cm distal to the base of the penis.[36,42] To perform the SQRB, the anesthetic is injected subcutaneously, above Buck's fascia, circumferentially on the shaft of the penis near its base (Fig 4A and B). To learn more about the use of the SQRB, view video clip 1.
Video clip 1
One argument against using a penile nerve block is that performing a block may be more painful than the circumcision itself. The local infiltration of lidocaine, the most commonly used anesthetic for neonatal circumcisions, is known to cause some discomfort. Researchers have attempted to discover ways in which this discomfort can be diminished, with mixed results. Buffering the lidocaine with sodium bicarbonate[43,44,45] or diluting it with normal saline or water[46,47] are 2 methods that have been prospectively evaluated. A recent study with 20 adult volunteers found that warming the buffered lidocaine before use was the most effective way to decrease the associated discomfort. Application of this technique to infants has not been evaluated for safety and efficacy.
The speed of lidocaine injection may contribute to the pain associated with tissue infiltration. One technique believed to diminish the pain of lidocaine injection is to administer the solution very slowly.[42,49] One author, in a step-by-step article on performing a DPNB, recommends that the needle on the syringe be filled with the lidocaine solution. He states a baby "is more likely to cry if there is air in the tip of the needle." The use of a fine 27-gauge or 30-gauge needle may also be preferable, given the potential to minimize "the mechanical trauma of injection."
Contrary to concerns about block-associated pain, studies have found that "the injection itself did not increase stress reactions nor did it offset the beneficial effects of anesthesia."[3,5] In clinical practice, the pain of administering a penile block seems to be minimal. When administering an SQRB, only the initial penetration of the skin and formation of the first bleb results in pain. Each remaining bleb initiates in the distal edge of a previous bleb, an area that already has been anesthetized. With the DPNB, the infant will feel the penetration of the skin twice, because the anesthetic must be injected into 2 previously unanesthetized areas.
A 0.5% or 1% lidocaine solution without epinephrine is the anesthetic most commonly used for both of these penile blocks. The lidocaine must not contain epinephrine because its injection into an area with end arteries, such as a finger, toe, nose, ear, or penis, may cause ischemia and result in tissue necrosis. The amount of lidocaine used for both the DPNB and SQRB is generally less than 1 mL. This is well within the acceptable dosage range for newborns.[37,41,50] There have been no reported systemic effects associated with lidocaine use for circumcisions.[36,37,51,52] The maximum dose of 1% lidocaine without epinephrine (1% lidocaine equals 10 mg/mL) in the newborn period is 4.5 to 5 mg/kg/dose per 2-hour period.[50,53] Penile nerve blocks do not affect voiding. No long-term adverse effects on urologic or sexual function in older men have been found.
The time associated with administering penile nerve blocks is sometimes cited as a disincentive to their use. The equipment needed for a penile block is simple and can be quickly assembled (Fig 5). See video clip 2. Both the SQRB and DPNB can be administered in less than 60 seconds, and the waiting time for their effect is approximately 3 and 5 minutes, respectively.[36,41,42] A practical approach to conserving time is to initially prepare the area to be injected and then administer the block. While waiting for the block to take effect, the circumciser can don sterile gloves and surgically prepare and drape the entire area. By the time this is done, the circumcision can be started, thus reducing overall waiting time.
Video clip 2
Equipment needed for penile nerve blocks.
Adv Neonatal Care. 2003;3(2) © 2003 W.B. Saunders
Cite this: A Pictorial and Video Guide to Circumcision Without Pain - Medscape - Apr 01, 2003.