VOLUME 30, ISSUE 2

Regional anesthesia is commonly used as an adjunct to general anesthesia to minimize the amount of opioids and volatile agents required, decrease the stress response to surgery, and provide long acting analgesia. Caudal blocks and dorsal penile nerve blocks are the two most common techniques to provide analgesia for pediatric urologic surgeries. While studies have shown advantages and disadvantages of caudal blocks and dorsal penile nerve blocks, the choice between the two techniques depends on the experience and comfort level of the anesthesiologist.

A dorsal penile nerve block is relatively easy to perform after the anatomy of the penis is reviewed. The dorsal veins and arteries travel close to the nerves; therefore, needle aspiration should always occur prior to injection of local anesthetic to minimize the risk of intravascular injection. By injecting the local anesthetic agent superficially, deeper structures such as the corpus cavernosum can be easily avoided. The multi-institutional study conducted by the Pediatric Regional Anesthesia Network (PRAN) has found that regional anesthesia performed in the pediatric population has a very low rate of complications¹. There were no complications or adverse events associated with the performance of a penile block in 230 patients across 14 institutions across the United States. A study performed by Ashrey et. al. found that penile blocks led to better hemodynamic stability intraoperatively and postoperatively compared to caudal blocks². Penile blocks also provided more effective and longer lasting pain relief without causing a motor block. Therefore, early ambulation was not impaired by penile blocks as it may be with caudal blocks. Kundra et. al. have reached similar conclusions in their randomized, double-blind study involving distal hypospadias surgeries³. They concluded that superior analgesia was achieved with penile blocks compared to caudal blocks. Furthermore, it was noted that the children who suffered from urethral fistula post-operatively had all been randomized to the caudal epidural group. Metzelder et. al. favor penile blocks over caudal anesthesia due to a lower incidence of micturition impairment and urinary retention⁴. These side effects can lead to great discomfort in a pediatric population and may result in longer hospitalization post-operatively. The relatively few contraindications to a dorsal penile nerve block include infection at the site of the block and suspected testicular torsion. Technically, it can be challenging to obtain an adequate field due to difficulty retracting the penis in our smallest patients. Lastly, a dorsal penile nerve block covers only one branch of the pudendal nerve. Therefore, it will only provide adequate analgesia for surgeries that involve the distal two thirds of the penis.

Caudal epidural anesthesia is one of the most commonly performed neuraxial techniques in the pediatric population. It has been shown to be a safe and effective method of anesthesia with a success rate of above 98% in experienced hands⁵. It can provide intraoperative and postoperative analgesia for procedures below the umbilicus and is frequently used for perineal, genitourinary, and ilioinguinal surgeries. Canakci et. al. compared caudal analgesia, dorsal penile nerve block, and subcutaneous morphine for analgesia during circumcision⁶. They discovered that the group with preemptive analgesia through caudal blocks had lower overall pain scores at the first hour and for up to 24 hours postoperatively. It was also shown that parent and patient satisfaction were highest in the caudal anesthesia group. Seyedhejazi et. al. demonstrated a higher success rate with caudal blocks compared to dorsal penile nerve blocks for hypospadias repair⁷. In addition, the patients in the penile nerve block group also required more analgesia postoperatively. However, some studies have suggested that caudal anesthesia can lead to poorer surgical outcomes in hypospadias repairs. Kim et al. has brought attention to the increased risk of postoperative complications associated with caudal blocks⁸. Complications included urethrocutaneous fistula, urethral stricture or diverticulum, and wound problems. There are several limitations to this study. First, it was limited to only one surgical technique: the tabularized incised plate repair. This technique is reported to have a high overall complication rate (33%), especially in proximal hypospadias cases, including a high incidence of postoperative fistulas (21%). Second, this study had a disproportionately high number of patients undergoing proximal repair (known to have higher complication rate) who were randomized to the caudal anesthesia group.

A prospective randomized multi-center trial (clinicaltrials.gov, NCT02861950) is underway with the purpose to determine whether there is an increased incidence of urethrocutaneous fistula after hypospadias repair with a caudal block compared to a penile block⁹. There is no conclusive evidence at this time to support or oppose the safety of caudal blocks compared to dorsal penile nerve blocks. In fact, numerous articles and studies support the use of caudal anesthesia for surgeries below the umbilicus, especially penile surgeries. The experience and comfort level of the anesthesiologist remain the most important factors in predicting the type of regional block performed and its success rate.