Anesthesia Options for Lateral Sphincterotomy
Lateral internal sphincterotomy can be safely performed under local anesthesia, general anesthesia, or spinal anesthesia, with local anesthesia being highly effective and offering significant socioeconomic advantages as an outpatient procedure. 1, 2, 3
Local Anesthesia (Preferred for Outpatient Setting)
Local anesthesia is a highly effective option that provides equivalent outcomes to general anesthesia with multiple practical advantages. 2, 3
Technique and Evidence
- Topical anesthetic cream (xylocaine 2%) can be applied first, followed by local anesthetic infiltration 2
- Multiple high-quality studies demonstrate no differences between local and general anesthesia in terms of operating time, postoperative pain, nausea/vomiting, pain-free interval, or patient satisfaction 2, 3
- Healing rates of 90-100% are achieved with local anesthesia, comparable to general anesthesia 1, 3
- Local anesthesia allows the procedure to be performed as an outpatient without hospital admission, operating room requirements, or preoperative studies 3
Important Caveat
- One older study from 1981 reported significantly higher failure rates with local anesthesia (50% recurrence) compared to general anesthesia (3% recurrence) 4
- However, multiple subsequent studies from 2001-2011 contradict this finding and demonstrate equivalent efficacy 1, 2, 3, 5
- The more recent evidence (2001-2011) should be prioritized, as surgical techniques and local anesthetic agents have evolved 1, 2, 3
General Anesthesia
General anesthesia remains a valid option, particularly for complex cases or patient preference. 5, 4
- Provides complete muscle relaxation and patient comfort during the procedure 5
- May be preferred when performing more extensive sphincterotomy or when patient anxiety is high 5
- Requires standard preoperative assessment and hospital/surgical center facilities 5
Spinal Anesthesia
Spinal anesthesia is an excellent alternative for anorectal procedures and is increasingly accepted in day surgery settings. 6, 7
Technical Considerations
- Low-dose spinal techniques with appropriate positioning (sitting position for perianal procedures) minimize side effects such as hypotension and prolonged motor blockade 6
- Smaller gauge needles (≥25G) and pencil-point needles reduce post-dural puncture headache risk to <1% 6
- Restrict intravenous fluids to no more than 500 ml to reduce urinary retention risk 6, 7
Mobilization Criteria After Spinal
- Return of sensation to the perianal area (S4-5) 6, 7
- Plantar flexion of the foot at pre-operative strength levels 6, 7
- Return of proprioception in the big toe 6, 7
Critical Analgesia Planning
- Start oral analgesics before the spinal block wears off to prevent breakthrough pain 6, 7
- Provide written instructions regarding timing of analgesic administration 6, 7
- Long-acting NSAIDs should be given prophylactically unless contraindicated 6
Common Pitfalls to Avoid
- Do not perform inadequate sphincterotomy under local anesthesia due to patient discomfort—ensure adequate anesthetic infiltration before proceeding 2, 3
- Avoid indiscriminate use of opioids (particularly morphine) as they increase postoperative nausea and vomiting without improving outcomes 6
- Do not discharge patients after spinal anesthesia without confirming return of perianal sensation and motor function 6, 7
- Ensure patients receive discharge instructions about post-dural puncture headache even though risk is <1% with modern techniques 6