What is a dorsal penile nerve block?

Dorsal Penile Nerve Block: Definition and Clinical Application

A dorsal penile nerve block (DPNB) is a regional anesthesia technique that provides sensory anesthesia to the penis by blocking the paired dorsal penile nerves, which are terminal branches of the pudendal nerve that provide sensory innervation to both the dorsal and ventral aspects of the penis. 1, 2

Anatomical Basis

• The pudendal nerves branch to form the paired dorsal nerves of the penis, which run along the dorsal aspect of the penis just deep to Buck's fascia 3
• These nerves provide sensory innervation to the skin of both the dorsal and ventral surfaces of the penis 1
• The perineal nerves (another branch of the pudendal nerve) also contribute to penile innervation and should ideally be anesthetized for complete analgesia 1

Technical Approaches

Subpubic Approach (Most Common)

• The block is performed using the subpubic space technique, where local anesthetic is injected into the fascial compartment just deep to Buck's fascia 4, 3
• Traditional landmark-based techniques include "10 o'clock and 2 o'clock" infrapubic injections with or without ventral infiltration or a ring block 3

Enhanced Technique

• Adding a ventral injection for perineal nerve analgesia significantly improves success rates, reducing failure from 6.4% to 0% in one study 1
• This combined approach reduces operating time and eliminates the need for supplemental anesthesia 1

Ultrasound-Guided Approach

• Ultrasound guidance allows precise targeting of the dorsal penile nerves in the fascial compartment just deep to Buck's fascia 3
• This technique potentially increases block success rate and reduces the need for large local anesthetic volumes 3
• The American Academy of Pediatrics recommends ultrasound guidance can improve accuracy 4

Local Anesthetic Selection

• Bupivacaine 0.25-0.5% without epinephrine is the preferred long-acting agent for penile surgery 4
• Ropivacaine 0.2% is an alternative with intermediate duration 4
• Maximum doses must be calculated: bupivacaine 1.3 mg/kg without epinephrine or 3.0 mg/kg with epinephrine 4
• Contrary to traditional teaching, epinephrine can be safely used in penile blocks at the lowest effective concentration 4
• Adding sodium bicarbonate to local anesthetic reduces injection pain 4

Clinical Indications

• Circumcision in both adults and children 5, 6
• Paraphimosis reduction 3
• Hypospadias repair 4
• Any penile surgical procedure requiring anesthesia 5

Success Rates and Complications

• Reported failure rates range from 3.3% to 6.7% with standard techniques 1, 6
• Minor complications include edema and hematoma (13-21% incidence) 6
• Inadvertent injection into the corpora cavernosa may occur with landmark-based techniques 3
• DPNB as sole anesthetic has advantages over general anesthesia plus DPNB, including shorter operating room time (11 vs 19 minutes) and recovery time (51 vs 101 minutes) 6

Safety Considerations

• Always aspirate before injection to avoid intravascular administration 4
• Calculate total dose in mg/kg to ensure it remains below toxic threshold 4
• Have lipid emulsion available for treatment of local anesthetic systemic toxicity 4
• The block should be combined with multimodal analgesia including NSAIDs and acetaminophen for optimal pain control 4