This document provides background information and details on the technique of performing a transversus abdominis plane (TAP) block. It begins with an overview of the TAP block, including its original description and subsequent modifications using ultrasound guidance. Next, it discusses the indications for TAP blocks, including postoperative analgesia for various abdominal surgeries. The anatomy section describes the layers and nerves of the abdominal wall targeted by the block. Finally, the technique section outlines the materials, patient positioning, ultrasound probe placement, needle insertion, and local anesthetic injection steps to perform a TAP block.

1. Dr Saeid Safari
Department of Anesthesiology and Pain Medicine, Tehran University of Medical
Sciences

2. Background and Indications:

3. Background
 The transversus abdominis plane, more
commonly referred to as the TAP block,
 Places local anesthetic in the lateral
abdominal wall in a plane between the internal
oblique and the transversus abdominis
muscles.
 Here, the local anesthetic block can block
many of the abdominal nerves as they pass to
the abdominal structures.

4. Background
 The TAP block was first described by McDonnell
et al' in 2006.
 Their original technique was a blind technique
using a blunt regional anesthesia needle and
relied on feeling a double pop as the needle
passed through the layers in an area known as
the triangle of Petit.
 Since then, the technique has been modified to
utilize ultrasound to confirm placement of the local
anesthetic.

5. Lumbar triangle of Petit between external oblique
muscle and latissmis dorsi.
CM: costal margin, IC: iliac crest.

6. Indication
 Bilateral TAP blocks to provide effective
postoperative analgesia compared with
morphine in
 prostatectomy,
 large and small bowel resection,
 cesarean section
 It is likely to be useful in providing pain relief
following many other abdominal surgical,
gynecological, and urological procedures.

7. Anatomy

8. Anatomy
 The abdominal wall between the iliac crest and
the subcostal margin consists of three layers
of muscle (external oblique, internal oblique,
transversus abdominis) covered by connective
tissue and skin.

9. Anatomy
1) There is a fascial sheath between the internal
oblique and transversus abdominis muscles.
The nerves lie deep to this fascia.
2) Nerves of T6-T9 enter the TAP medial to the
anterior axillary line.

10. Anatomy
 T6 enters the TAP just lateral to the linea alba,
and T7-T9 at progressively increasing distances
from the linea alba.
 Nerves running in the TAP lateral to the anterior
axillary line, on the other hand, originate from
segmental nerves T9-L1.
 This may explain the observation of some authors
that the TAP block is only suitable for lower
abdominal surgery.

11. Anatomy
 There is extensive branching and
communication of the segmental nerves in the
TAP.
 In particular the T9-L1 branches form a so-
called "TAP plexus" that runs with the deep
circumflex iliac artery.
 This may partly account for the ability of a
single injection to cover several segmental
levels.

15. Cross Section
Through The
Abdomen.
 EO, external oblique muscle;
 IO, internal oblique muscle;
 TA, transversus abdominus
muscle;
 IC, intercostal nerves;
 IL, ilioinguinal nerve;
 IH, iliohypogastric nerve;
 PS, psoas;
 ES, erector spinae;
 VB, vertebral body;
 QB, quadratus lumborum.

16. Anatomy
 The transversus abdominis is the deepest
layer, and below is the peritoneum. The skin,
muscles, and peritoneum of the anterior
abdominal wall are innervated by the lower 6
thoracic nerves and the first intercostals nerve.

17. Anatomy
 At the costal margin, thoracic nerves 7 to 11
leave their intercostals spaces and enter the
neurovascular plane of the abdominal wall
between transversus abdominis and internal
oblique.
 Running across the surface of the transversus
abdominis muscle and aponeurosis are the
lower intercostals, subcostal, and
iliohypogastric nerves.

18. Technique

19. Technique
 Patient Position: Supine.
 Probe: 40- or 60-mm curved array oscillating at 3 to 8 MHz.
 Probe Position: Transverse or transverse oblique between
the margin of the 12th rib and superior iliac spine.
 Needle: 22-gauge blunt needle (5-10 cm) for single injection.
18-gauge Tuohy needle (5-10 cm) for continuous infusions.
 Local Anesthetic: Bupivaciane 0.25% (20-30 mL), ropivacaine
0.2% (20-30 mL).

20. Technique:
 This block may be performed before or
following induction of general or spinal
anesthesia.
 The patient needs to be lying supine.
 An aseptic technique is advocated using a no-
touch technique, an appropriate cleaning
solution, and a sterile cover for the ultrasound
probe.

21. Technique
 The ultrasound probe is positioned horizontally
on the skin just above the iliac crest in the
midaxillary line.
 The muscle layers are identified. We prefer to
use a peripheral nerve block needle because it
allows "distant" injection by your assistant
while you remain in control of ultrasound probe
and needle.
 A 50-mm needle is usually sufficient.

22. Technique
 We use an in-plane approach inserting the
needle posteriorly and directing anteriorly.
 The needle is followed under direct vision as it
passes through the muscle layers.
 Tip lies between the internal oblique and
transversus abdomenus muscles.

23. Schematic view of an ultrasound-
guided tranaversus abdominis plane
block.
 EO: external
oblique, IO: internal
oblique, TA:
transversus
abdominis, LA: local
anaesthestic

25. Probe and Needle Position for TAP
Block.

27. Technique
 Injection of the local anesthetic must be seen
to ensure correct placement.
 It is very characteristic to see the layer
expanding in an ellipsoid way.
 We use of 20 mL of 0.5% ropivacaine resulting
in a block from T8 to the symphysis pubis.

28. Ultrasound Scan Through The
Abdomen.

29. Ultrasound Scan with Needle.

30. Ultrasound Scan after Local
Anesthetic Injection.