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NervesLevel blocked
  • Subcostal nerves (T9–L1)
  • Ilioinguinal/iliohypogastric
  • nerves (T12–L1)
  • T10–L1 blocked reliably
  • T9 blocked 50%
  • T4–T8 described but inconsistently blocked:
  • No analgesia above umbilicus
  • Covers skin, muscle, and parietal peritoneum
  • Visceral structures not blocked


  • Unilateral block: postoperative analgesia following inguinal hernia repair, appendectomy, renal transplant, anterior iliac crest bone harvest
  • Bilateral block: median laparotomy, radical prostatectomy, hysterectomy, various laparoscopic procedures, C-section; typically performed preoperatively, except for C-section


Landmarks “blind” technique:

  • Patient supine, arm abducted to allow access to lateral abdomen
  • Identify the triangle of Petit (delimited by latissimus dorsi, iliac crest, and external oblique):
    • Can be very difficult in obese patients
  • Needle inserted perpendicular to the skin
  • “Double pop” felt as needle inserted (blunt needle gives more obvious pops):
    • First pop—fascia between external and internal oblique muscles
    • Second pop—fascia between internal oblique and transverse abdominis muscles
  • Twenty milliliters of local anesthesia is injected

Ultrasound technique (Figure 152-1):

  • Landmarks: between costal margin and iliac crest in midaxillary line
  • Muscle planes are identified with a high-frequency (8–13 MHz) probe
  • Muscles are hypoechoic (dark); fascia is hyperechoic (bright)
  • A 100-mm short-bevel needle inserted in-plane, anterior to posterior (i.e., from the medial side). An out-of-plane approach is also possible but requires more experience
  • Inject a few milliliters of saline to ascertain correct position of needle tip
  • Local deposition in the fascial layer between the internal oblique and transverse abdominis muscles; typically 15–20 mL of 0.25% bupivacaine or ropivacaine
  • Oblique subcostal approach has been tried to increase block height: probe placed parallel along the costal margin, needle inserted in an in-plane technique from lateral to medial

Figure 152-1. Probe and Needle Placement

(A) “Traditional” TAP block. The needle can be introduced from the medial or the lateral side in-plane, or it can be placed out-of-plane. IC: iliac crest; CM: costal margin. (B) Oblique subcostal approach: probe parallel to the costal margin. The needle is typically inserted in-plane from the lateral side (not shown).

Figure 152-2. Ultrasound Target for the TAP Block

The TAP plane, between internal oblique and transverse abdominis muscles, is the target for the local anesthetic injection.


  • Pinprick testing can be performed to assess block level
  • Block is most commonly done for postoperative analgesia after induction of general anesthesia
  • Block is dependent on volume, not concentration; 20 mL of 0.25% bupivacaine routinely gives 18–24 hours of analgesia

Side effects/complications:

Low-risk analgesic block:

  • General risks:
    • Needle trauma
    • Intravascular injection
    • Local anesthetic toxicity
    • ...

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