Can a unilateral ultrasound‑guided transversus abdominis plane (TAP) block be used as the primary anesthetic for an adult undergoing elective inguinal hernioplasty when general or neuraxial anesthesia is contraindicated (e.g., severe pulmonary disease, coagulopathy, or preference to avoid intubation)?

TAP Block as Primary Anesthetic for Inguinal Hernioplasty

Yes, ultrasound-guided TAP block combined with ilioinguinal/iliohypogastric (II/IH) nerve block can serve as the primary anesthetic for elective inguinal hernioplasty in adults when general or neuraxial anesthesia is contraindicated, though supplemental local infiltration or minimal sedation may be required for complete surgical anesthesia. 1, 2, 3

Evidence for TAP Block as Primary Anesthetic

Feasibility in High-Risk Patients

• A retrospective case-control study demonstrated successful tension-free Lichtenstein inguinal hernia repair using TAP block alone without general, spinal, or epidural anesthesia in elderly high-risk patients who could not tolerate conventional anesthesia 1
• This approach showed fewer anesthesia-related complications (postspinal headache, urinary retention, hypotension from peripheral vasodilation) compared to spinal anesthesia 1

Optimal Block Technique: "Double TAP" Approach

• Combining TAP block with II/IH nerve block (the "double TAP" technique) provides superior intraoperative anesthesia compared to either block alone 2, 3
• The double TAP technique resulted in adequate surgical anesthesia in 87.5% of patients versus only 63% with II/IH block alone, with significantly fewer patients requiring systemic sedation (12.5% vs 37%, P < 0.05) 3
• This combined approach is specifically recommended for patients wishing to avoid general anesthesia 2

Technical Execution

Block Performance

• Use ultrasound guidance to reduce local anesthetic systemic toxicity risk, improve needle placement accuracy, and allow for reduced volumes 4, 5
• Perform the TAP block using 20 mL of 0.2% ropivacaine or 0.125-0.25% bupivacaine, as lower concentrations (0.125%) provide similar analgesic efficacy to higher concentrations (0.25%) 6, 7
• Add the II/IH nerve block to ensure complete coverage of the surgical field 2, 3

Safety Considerations

• Calculate safe local anesthetic dose based on patient weight to prevent systemic toxicity 4, 8
• Have resuscitation equipment immediately available at bedside 4
• Monitor blood pressure and electrocardiogram continuously, especially in patients with cardiovascular risk 4, 8
• Use standard aseptic technique similar to neuraxial procedures 8

Advantages Over Neuraxial Techniques in High-Risk Patients

Hemodynamic Stability

• No sympathectomy-induced hypotension occurs with peripheral blocks, unlike neuraxial techniques that cause peripheral vasodilation 5, 1
• Peripheral nerve blocks produce fewer physiological consequences and hemodynamic side-effects compared to neuraxial techniques 5

Reduced Complications

• Lower risk of urinary retention compared to epidural or spinal anesthesia 5, 1
• Avoids delayed mobilization from motor paralysis associated with neuraxial blocks 1
• No risk of post-spinal headache 1

Coagulopathy Considerations

• TAP blocks fall into the low-risk category for hemorrhagic complications, as bleeding would be easily controllable and the area is compressible 4
• This makes TAP blocks particularly suitable when coagulopathy is a contraindication to neuraxial techniques 4

Postoperative Analgesia Benefits

Duration and Quality

• TAP block with ropivacaine provides analgesia lasting approximately 390 minutes (6.5 hours) 6
• Significantly reduces pain scores at 4,6, and 12 hours postoperatively 6
• Patients report lower pain scores at end of surgery (0.4 vs 2.1), at 2 hours (0.8 vs 3.0), at discharge (1.4 vs 4.3), and at 24 hours (1.5 vs 4.5) when TAP is combined with II/IH block 3

Opioid-Sparing Effect

• Total analgesic consumption is significantly reduced compared to placebo 6
• The opioid-sparing effect is particularly beneficial for reducing respiratory complications and delirium in high-risk patients 5

Guideline Support for Regional Techniques

Strong Recommendations

• Regional anesthesia techniques are effective in both adults and children for site-specific surgery (strong recommendation, high-quality evidence) 9
• Abdominal wall blocks can be considered a technique with an opioid-sparing effect (intermediate recommendation, intermediate quality evidence) 9
• TAP block in patients undergoing laparoscopic abdominal surgery is proven to be safe and effective for treating postoperative pain (intermediate recommendation, intermediate quality evidence) 9

Evidence from Emergency Surgery

• Multiple meta-analyses indicate that TAP blocks in patients undergoing abdominal surgery are associated with decreased pain scores (both at rest and with activity) and reduction in opioid consumption 9
• TAP blocks provide long-lasting analgesic effect compared to local wound infiltration alone 9

Critical Limitations and Backup Planning

Incomplete Anesthesia Risk

• Approximately 12.5% of patients may still require supplemental systemic sedation even with the double TAP technique 3
• Have a clear plan for conversion to general anesthesia or supplemental sedation if the block proves inadequate 3
• Thoroughly test for block success before proceeding with surgery to avoid inadequate anesthesia 4, 8

Anatomical Coverage Gaps

• TAP block primarily covers T7-L1 dermatomes; ensure the surgical field falls within this distribution 6
• The inguinal region may require additional local infiltration by the surgeon for complete coverage, particularly for deeper structures 2, 3

Multimodal Analgesia Integration

Adjunctive Medications

• Combine with scheduled acetaminophen and NSAIDs (if not contraindicated) to supplement the block 4
• Consider local wound infiltration as a component of multimodal analgesia (weak recommendation, moderate quality evidence) 9
• Balance the benefit of perineural adjuvants against risks of immunosuppression, sedation, bradycardia, and hypotension 8

Avoiding Pitfalls

• Do not refuse regional anesthesia solely based on patient age or comorbidities—this represents outdated practice 5, 1
• Never perform the block without ultrasound guidance in modern practice, as this increases safety and reduces required volumes 5, 8
• Exercise caution when using multiple sources of local anesthetics; reduce doses accordingly to minimize risk of systemic toxicity 9