What is the recommended protocol for administering a penile block?

Penile Block Protocol

For penile surgery in both adults and children, perform a dorsal penile nerve block using the subpubic (infrapubic) approach with long-acting local anesthetic, specifically bupivacaine 0.25-0.5% without epinephrine, combined with multimodal analgesia including NSAIDs and acetaminophen. 1, 2, 3

Technique Selection

Subpubic/Infrapubic Approach (Preferred)

• Insert a short bevel needle into the two compartments of the subpubic space where the dorsal nerves run before entering the base of the penis 3
• This median technique requires only one injection in the subpubic space near the posterior inferior aspect of the symphysis 4
• Bilateral diffusion of anesthetic has been demonstrated with this single-injection approach 4
• Add subcutaneous infiltration at the penile root to improve analgesia quality 4, 5

Alternative: Bilateral Technique

• Each penile nerve is blocked separately at the level of the penile root 4
• More reliable in adults when contralateral diffusion is uncertain (occurs in only 60% of cases with unilateral injection) 4

Local Anesthetic Selection

First-Line: Bupivacaine

• Use 0.25% or 0.5% bupivacaine without epinephrine 2, 4, 3
• Volume: 0.1 mL/kg body weight in children 3
• Volume: 20 mL total in adults 6
• Provides 10+ hours of postoperative analgesia 4, 3
• Maximum dose: 1.3 mg/kg without epinephrine, 3.0 mg/kg with epinephrine 2

Alternative Options

• Lidocaine 1% (shorter duration, 4-6 hours) 3
  • Maximum dose: 4.4 mg/kg without epinephrine, 7.0 mg/kg with epinephrine 2
• Ropivacaine 0.2% (intermediate duration) 2
  • Maximum dose: 2.0 mg/kg without epinephrine, 3.0 mg/kg with epinephrine 2
• 50:50 mixture of 0.5% bupivacaine and 0.5% lidocaine for balanced onset and duration 5

Epinephrine Controversy

Traditional Teaching vs. Current Evidence

• Epinephrine can be safely used in penile blocks contrary to traditional teaching about terminal vessel areas 2, 7
• A retrospective study of 95 patients using ropivacaine/lidocaine with epinephrine showed no anesthetic-related complications 2, 7
• Benefits include prolonged effect, reduced bleeding, and improved surgical visualization 2, 7

Practical Recommendation

• If using epinephrine, use the lowest effective concentration 2
• Most practitioners still avoid epinephrine given adequate analgesia duration with plain bupivacaine and theoretical concerns 4, 3
• The evidence supporting epinephrine safety is limited to single retrospective studies 2, 7

Safety Measures

Pre-Injection

• Calculate total dose in mg/kg before administration to prevent local anesthetic systemic toxicity 2
• Aspirate before injection to avoid intravascular administration 2
• Have lipid emulsion available for treatment of local anesthetic systemic toxicity 2

Technique Refinements

• Add sodium bicarbonate to local anesthetic to reduce infiltration pain 2
• Use ultrasound guidance when available for improved accuracy 1, 6
• If venous blood reflux occurs, withdraw and reinsert the needle 3

Multimodal Analgesia Protocol

Pediatric Patients (Hypospadias Repair)

Basic Level: 1

• Rectal NSAID
• Rectal paracetamol
• Landmark-based penile block with long-acting local anesthetic

Intermediate Level: 1

• IV or rectal NSAID
• IV loading dose of paracetamol
• Ultrasound-guided caudal block with long-acting local anesthetic +/- clonidine as alternative to penile block

Postoperative: 1

• Oral or rectal NSAIDs throughout postoperative period
• Oral or rectal paracetamol throughout postoperative period
• Tramadol or nalbuphine as rescue analgesic

Adult Patients

• Combine penile block with systemic analgesics for optimal pain control 4, 5
• Pre-operative sedation recommended, though 93% of patients tolerate procedure without booster sedation 5
• Monitored anesthetic care should be available as 5-7% may require additional sedation or conversion to general anesthesia 5

Common Pitfalls

Avoid These Errors

• Do not use epinephrine-containing solutions without careful consideration of risk-benefit ratio given limited evidence 2, 7
• Do not exceed maximum local anesthetic doses - calculate total mg/kg before injection 2
• Do not rely on penile block alone in adults - have backup sedation/anesthesia available 5
• Do not perform unilateral injection in adults - use bilateral technique or median approach with proven bilateral diffusion 4

Expected Outcomes

• Success rate approaches 100% when technique is properly performed 3
• Postoperative analgesia duration: 10+ hours with bupivacaine 4, 3
• Short-term complications may include swelling (42%), pain (19%), hematoma (13%) - these are surgical, not anesthetic complications 7