Urinary Anesthetic Medications
For urinary tract procedures, topical lidocaine (1-2% solution instilled intravesically for 10-15 minutes) is the primary anesthetic agent, providing safe and effective pain control for bladder biopsies, cautery, and cold-cup resections in most patients, though caudal or spinal anesthesia offers superior pain relief for more extensive procedures. 1, 2
Topical Intravesical Anesthesia
Lidocaine is the gold standard topical agent for bladder procedures:
- Instill 20-50 mL of 1-2% lidocaine solution intravesically and retain for 10-15 minutes before the procedure 1, 2
- Provides adequate pain control in 94% of patients undergoing bladder mappings and cold-cup biopsies 2
- Mean pain scores of 1.6 (on 0-5 scale) for cold-cup biopsies and 2.7 for cautery—considered tolerable by most patients 1
- Serum lidocaine levels remain negligible (measured at 7-15 minutes post-instillation), confirming safety with minimal systemic absorption 1, 2
- Maximum safe dose for intravesical use: 4.5 mg/kg without epinephrine 3
Bupivacaine offers longer duration for urethral procedures:
- For urethral anesthesia requiring prolonged effect, use 20-22 mL of bupivacaine gel (0.25-0.5%) 4
- Provides 141 minutes of anesthesia compared to 29 minutes with lidocaine 4
- Particularly useful for transurethral procedures and post-operative pain management 4
- Serum absorption is slow with wide safety margin at 50 mg dose 4
Tetracaine 2% is FDA-approved for topical urinary tract anesthesia 5
Regional Anesthesia for Urinary Procedures
Caudal anesthesia provides superior pain control compared to topical agents:
- Mean pain scores of 0.8 for biopsies and 1.0 for cautery (significantly lower than topical lidocaine, p<0.01) 1
- Consider caudal block when topical anesthesia proves inadequate or for larger lesions requiring resection rather than cold-cup biopsy 1, 2
Spinal anesthesia considerations:
- Lidocaine for spinal anesthesia causes detrusor blockade lasting 235±30 minutes 6
- Bupivacaine for spinal anesthesia causes significantly longer detrusor blockade (460±60 minutes) with risk of bladder overdistension 6
- Spontaneous voiding does not return until sensory block regresses to S3 level 6
- For urinary procedures, short-acting lidocaine is preferable to bupivacaine for spinal anesthesia to minimize postoperative urinary retention 6
- Accumulated urine volume with bupivacaine (875±385 mL) significantly exceeds normal bladder capacity (505±120 mL), creating overdistension risk 6
Specialized Techniques
Intracorpus spongiosum anesthesia for anterior urethral procedures:
- Inject 3 mL of 1% lidocaine slowly into the glans penis 7
- Provides immediate anesthetic effect with 92% of patients experiencing zero pain 7
- Safe for procedures averaging 33 minutes duration 7
- Two cases (3.9%) experienced transient vasovagal response during injection—have patient supine and monitor closely 7
Critical Safety Considerations
Dosing limits to prevent systemic toxicity:
- Lidocaine maximum: 4.5 mg/kg without epinephrine, 7.0 mg/kg with epinephrine 3
- Bupivacaine maximum: 2.5-3.0 mg/kg 3, 8
- Calculate maximum allowable dose before starting procedure 3
- Use ideal body weight for dose calculations in obese patients 3
Monitoring requirements:
- Document vital signs every 5 minutes initially, then every 10-15 minutes once stable when using maximum doses 3, 9
- Watch for early toxicity signs: circumoral numbness, metallic taste, tinnitus 10, 3
- Have 20% lipid emulsion immediately available for local anesthetic systemic toxicity (LAST) treatment 8, 9
Common Pitfalls and How to Avoid Them
Inadequate topical anesthesia occurs with:
- Lesions >2 cm requiring resection rather than cold-cup biopsy 2
- Tumors on anterior bladder wall (poorly accessible) 2
- Insufficient contact time—ensure 10-15 minute dwell time before procedure 1, 2
Bladder overdistension after spinal anesthesia: