Chapter 146. Anesthesia of the Penis, Testicle, and Epididymis

A wide range of urologic procedures are performed using local or regional anesthesia. This includes an orchiectomy, inspection of the painful testis, release of a paraphimosis, dorsal slit, circumcision, and even a hydrocelectomy or varicocelectomy done in the Operating Room. Emergency Physicians can utilize some of the same anesthetic techniques, namely the penile or spermatic cord blocks, to safely and painlessly perform many procedures in the Emergency Department. These techniques are easy to learn, simple to perform, and have a low risk of serious complications.

Innervation of the penis arises from the pudendal nerve that is derived from sacral levels 2 to 4. The pudendal nerve divides into the perineal and the inferior rectal nerves. The perineal nerve further divides into the right and left dorsal nerves of the penis. The dorsal nerves of the penis pass under the pubic symphysis to penetrate the suspensory ligament of the penis.1 They travel under Buck's fascia to supply sensory innervation to the entire penis (Figure 146-1).

The primary nerve supply of the testis and epididymis are from the ilioinguinal and genitofemoral nerves. The ilioinguinal nerve is derived from the first lumbar spinal nerve. It arises slightly inferior and medial to the anterior superior iliac spine and courses toward the pubic tubercle, between the internal and external oblique muscles.1,2 It enters the inguinal canal on the anterior surface of the spermatic cord. The ilioinguinal nerve provides sensory innervation to the skin of the upper thigh, base of the penis, and the upper scrotum.3 It also provides sensory innervation to the spermatic cord and testicle. The genitofemoral nerve is derived from the first two lumbar spinal nerves. It divides into the genital branch and the femoral branch. The genital branch enters the inguinal canal at the external inguinal ring and travels with the spermatic cord. It provides sensory innervation to the lower scrotum, cremaster muscle, spermatic cord, and scrotum. The femoral branch supplies the skin of the anteromedial thigh.3

Emergency Department procedures that are facilitated by local anesthesia of the penis include a dorsal slit of the foreskin, release of a phimosis or paraphimosis, repair of penile lacerations, and the release of penile skin entrapped in zippers. Local anesthesia can also be used before performing a circumcision. However, this procedure is usually not performed in the Emergency Department.

The Emergency Department indications for a spermatic cord block include the relief of epididymal pain, the facilitation of a manual or ultrasound examination when differentiating between torsion and epididymitis, and to inspect the testis following trauma. Manual detorsion of a testis may be enabled by local anesthesia when a patient cannot tolerate the pain of palpation. This should be performed only if the patient will be taken immediately to the operating room for confirmation of detorsion and an orchiopexy. However, the risk of compromising the blood supply to the testis and the loss of patient assessment of pain in determining the success of detorsion are often cited as contraindications to spermatic cord blockade when testicular torsion is suspected.

Local anesthesia is contraindicated in testicular torsion, as there is a risk of compromising the testicular blood supply. The anesthetic effect will also eliminate the patient's assessment of pain that is needed to determine the success of manual detorsion. Agents containing epinephrine are not to be used in or around the penis.4 The arteries of the penis are end arteries and vasoconstriction can result in tissue ischemia and sloughing. To minimize the spread of infection, local anesthetic should not be directly injected into an area of local infection.

• 25 and 27 gauge needles
• Syringes (3, 5, and 10 mL)
• Povidone iodine or chlorhexidine solution
• Alcohol pads
• 4 × 4 gauze squares
• Local anesthetic solution without epinephrine

Several local anesthetic agents are commonly used for genitourinary anesthesia. These include lidocaine, bupivacaine, mepivacaine, and chloroprocaine (Table 146-1). The anesthetic agent, concentration, and technique must be chosen so that the maximum safe dose is not exceeded. This is especially important when performing anesthesia in children.

The patient must be informed of the procedure, including its risks and benefits. The explanation must include the risks of local anesthetic injection and the possibility that the anesthetic may not effectively eliminate pain. The risks associated with the injection include pain, hematoma formation, and bleeding. Infection is a late risk that can be reduced by prepping the skin and using sterile technique. Obtain an informed consent for the anesthetic procedure in addition to the consent for the procedure that will be performed under anesthesia.

The patient's ability to cooperate with the planned procedures must be assessed. Consider oral or parenteral sedation, especially in anxious patients or children. Midazolam (0.02 to 0.04 mg/kg IV) or diazepam (2.5 to 5 mg IV) are often good choices in adults. Children may benefit from midazolam parenterally (0.05 to 0.15 mg/kg IV) or orally (0.5 to 0.7 mg/kg). Ketamine (1.0 to 1.5 mg/kg IV or 2 to 5 mg/kg IM) combined with atropine (0.01 mg/kg) to reduce respiratory secretions is an alternative, especially in children younger than 10.

Clean any dirt and debris from the skin. Identify the anatomic landmarks required to perform the anesthetic injection. Apply povidone iodine or chlorhexidine solution to the area where the anesthetic is to be injected. The povidone iodine or chlorhexidine may also be applied to the penis and scrotum if an invasive procedure is subsequently to be performed. Apply sterile drapes to delineate a surgical field. Allow the povidone iodine or chlorhexidine to dry. Put on sterile gloves and reidentify the anatomic landmarks. Infiltrate with local anesthetic solution using sterile technique.

Local Infiltration

Local anesthetic infiltration of the skin of the penis is useful for the repair of superficial lacerations, dorsal slits of the foreskin, or freeing entrapped skin from a zipper. Local infiltration circumferentially around the penis will provide adequate anesthesia distal to the anesthetic injection site. The circumferential subcutaneous injections can be performed directly on the penis or on the abdominal wall and scrotum surrounding the penis. While not contraindicated, some authors avoid direct infiltration of the foreskin as tissue sloughing may result.2 Local infiltration of anesthetic agents is often extremely painful for the patient. Consider premedicating the patient with parenteral benzodiazepines and/or narcotic agents.

Local anesthetic agents can be injected subcutaneously into the penis to provide distal anesthesia. If performing a dorsal slit of the foreskin, raise a skin wheal of local anesthetic solution at the base of the foreskin in the 12 o'clock position (Figure 146-2A). Insert the needle through the skin wheal aimed distally. Inject local anesthetic solution subcutaneously as the needle is advanced to the distal edge of the foreskin. Alternatively, local anesthetic solution can be circumferentially infiltrated around the penis (Figure 146-2B). This block usually requires 6 to 10 mL of local anesthetic solution in the adolescent or adult and 2 to 3 mL in a child.

Penile Block

The objective of a penile block is to anesthetize the right and left dorsal nerves of the penis that provide sensation to the penis (Figure 146-1). The dorsal nerves should be blocked as close to the base of the penis as possible. If the block is performed too distal to the pubic bone, the posterior branches of the dorsal nerves will not be anesthetized and the ventral surface of the penis will retain sensation.5,6 Multiple effective techniques will be described to perform a penile block. The technique chosen should depend on the specific procedure to be performed, the level of patient cooperation, and the preference of the Emergency Physician.

The penis may be anesthetized where it forms along the abdominal wall.2 This block anesthetizes the nerves to the penis before they reach the penis. Form three skin wheals using local anesthetic solution on the abdominal and scrotal skin, 0.5 to 1.0 cm from the base of the penis, at the 2 o'clock, 6 o'clock, and 10 o'clock positions (Figure 146-3). Infiltrate subcutaneously with local anesthetic solution between the skin wheals to form a triangle of local anesthetic that surrounds the base of the penis. This block usually requires 8 to 12 mL of local anesthetic solution in the adolescent or adult and 3 to 5 mL in a child.

The dorsal nerves of the penis can be anesthetized as they course onto the penis. Place a skin wheal of local anesthetic solution at the 1 o'clock and 11 o'clock positions. Slowly insert a 27 gauge needle through the skin wheals until there is a slight loss of resistance indicating penetration of Buck's fascia (Figure 146-4). Aspirate to ensure that the needle is not within a blood vessel. Inject 1 mL of local anesthetic solution at each site in the adolescent or adult and 0.3 to 0.5 mL in a child.1

Another technique blocks the dorsal nerves as they pass through the triangular space bordered by the pubic symphysis, the corpora cavernosa, and Buck's fascia. Place a skin wheal of local anesthetic solution at the dorsal base of the penis. Insert the needle through the skin wheal and to the pubic symphysis. Withdraw the needle slightly and advance it caudally until a loss of resistance is felt, indicating that it has penetrated Buck's fascia. Aspirate to ensure that the needle is not within a blood vessel. Inject 10 mL of local anesthetic solution on each side of the suspensory ligament (midline) in the adolescent or adult and 2 to 3 mL in a child. Alternatively, the same block can be accomplished with a separate injection on each side of the midline.1,7

Spermatic Cord Block

As the spermatic cord exits the external inguinal ring, it passes over the pubic tubercle and continues medially toward the scrotum. In this same location, the ilioinguinal nerve travels on the anterior surface of the spermatic cord and the genital branch of the genitofemoral nerve on the posterior surface. These two nerves supply sensation to the spermatic cord, epididymis, and testicle. Anesthesia of the spermatic cord in the region of the pubic tubercle will provide anesthesia to the testis and its covering, the epididymis, and the vas deferens.6 The spermatic cord block does not provide anesthesia to the skin of the scrotum. Additional subcutaneous infiltration is necessary for an incision of the scrotal skin.

This first spermatic cord block technique is useful in thin patients with a palpable pubic tubercle. Identify the pubic tubercle by palpation. Inject local anesthetic solution to make a skin wheal just medial and 1 cm below the pubic tubercle (Figure 146-5). Gently advance a 25 gauge needle laterally through the skin wheal and spermatic cord until bone is contacted. Aspirate to ensure that the needle is not within a blood vessel. Inject 3 to 4 mL of local anesthetic solution as the needle is slowly withdrawn in the adolescent or adult and 1 to 2 mL in a child. Repeat the procedure two more times using the same skin puncture site, each time passing through the cord at a slightly different angle. This block requires a total of 10 to 12 mL of local anesthetic solution in the adolescent or adult and 3 to 5 mL in a child.6

A modified technique is used for the patient in whom the pubic tubercle is difficult to palpate. Grasp the spermatic cord between the nondominant thumb and index finger as it enters the scrotum (Figure 146-6). Place a wheal of local anesthetic solution between the fingers and above the spermatic cord. Insert a 25 gauge needle through the skin wheal. Direct the needle anterior to the spermatic cord. Aspirate to ensure that the needle is not within a blood vessel. Inject 3 to 4 mL of local anesthetic solution in the adolescent or adult and 1 to 2 mL in a child. Repeat the process on the medial and lateral side of the spermatic cord.

Alternatively, palpate the spermatic cord as it enters the scrotum.8 Trace the spermatic cord superiorly to the pubic tubercle where it exits the external inguinal ring. Trap the spermatic cord between the second and third fingers of the nondominant hand and the pubic tubercle. Place a wheal of local anesthetic solution between the fingers and above the spermatic cord. Insert a 25 gauge needle through the skin wheal. Aspirate to ensure that the needle is not within a blood vessel. Inject local anesthetic solution anteriorly, medially, and laterally to the spermatic cord as described above. Injection of local anesthetic solution around the spermatic cord as it exits the inguinal canal may be less painful than injection as it enters the scrotum.

Allow 10 to 15 minutes for the local anesthetic solution to take effect for a penile block. Test the level of anesthesia by pinching the skin with a forceps or by pin-prick with a needle. The patient may feel a pressure sensation, but should not feel pain. If the test stimulus is painful, repeat the block or use additional anesthetic techniques prior to performing the procedure.

Spermatic cord blocks require 10 to 15 minutes for maximal effectiveness. The patient should be warned that, despite an effective block, traction on the spermatic cord might cause nausea and a tugging sensation. These will resolve upon release of the traction.6 Additional anesthesia must be applied to the scrotal skin for any incisions or procedures as a spermatic cord block does not anesthetize the scrotal skin.

Minimal aftercare is required for these local anesthetic techniques. Depending on the agent used, sensation may return in as little as 1 to 2 hours with lidocaine and chloroprocaine or up to 4 hours with bupivacaine. The skin may reawaken with a pins-and-needles sensation. Patients should use caution when zipping their pants so as not to catch the penis, foreskin, or scrotum as they will not feel the injury. Patients should be warned that the site of a spermatic cord block might remain tender for as long as 10 days.6 The application of cool compresses to the injection site and oral nonsteroidal anti-inflammatory drugs will provide adequate analgesia for injection site pain. Patients should inspect the injection site and surrounding area three to four times a day for any signs of infection. They should return to the Emergency Department immediately if any problems or concerns arise.

The most procedure-specific complication of a penile block is sloughing of the penile skin. This is more common in the region of the glans. Performing the penile block at the base of the penis and using solutions without epinephrine minimizes this risk.

Hematomas can be quite large in spermatic cord blocks because the venous plexus is usually pierced. The use of a smaller needle and careful application of pressure can help prevent hematomas. Blood loss from puncturing a vascular structure is easily controlled with direct pressure. A Urologist should be consulted urgently in the rare occasion that bleeding does not resolve with pressure. Most hematomas will resolve within 1 to 2 weeks. The application of warm compresses to the hematoma several times a day may result in quicker resorption.

Local infection at the injection site is possible. Patients should be warned about the signs of infection including fever, erythema, warmth, induration, increased pain, and purulent drainage. Patients should seek immediate medical attention for any of these symptoms.

Toxic levels of anesthetic agents can affect multiple organ systems, most notably the central nervous and cardiovascular systems. Anesthetic agents block the inhibitory neurons of the brain producing a state of neuroexcitation. Initial symptoms may include tinnitus, premolar numbness, disorientation, lightheadedness, or nystagmus. This may progress to seizures that can be accompanied by slow or absent breathing, acidosis, aspiration, and cardiovascular instability. Intravenous diazepam (2.5 to 5 mg) at the first sign of symptoms may stop the cascade.2 Significantly higher doses of diazepam are required to treat seizures. Very high levels of local anesthetics are cardiotoxic and may result in heart block. Heart block from bupivacaine toxicity is associated with resistance to resuscitative maneuvers. The onset of all local anesthetic toxicities is faster with intravascular injection versus toxic tissue concentrations.

Local anesthesia allows many painful genitourinary procedures to be performed in the Emergency Department. The techniques are simple and easy to perform with little to no experience. Local anesthetic solutions containing epinephrine should never be used to anesthetize the penis, scrotum, or spermatic cord.