Abdominal nerve block techniques

INTRODUCTION — A variety of truncal peripheral nerve blocks can be performed to provide anesthesia and/or analgesia for abdominal wall procedures. Abdominal truncal nerve blocks are performed by injection of local anesthetic (LA) into fascial planes through which intercostal nerves run. They include:

●Transversus abdominis plane (TAP) block

●Ilioinguinal (II) and iliohypogastric (IH) blocks

●Rectus sheath blocks

●Transversalis fascia plane blocks

●Quadratus lumborum (QL) plane blocks

Unilateral blocks are used for one-sided procedures, such as appendectomy, cholecystectomy, nephrectomy, and renal transplant, while bilateral blocks are used for midline and transverse abdominal incisions, such as ventral or umbilical hernia, laparotomy, laparoscopic procedures, colostomy closures, cesarean section, hysterectomy, or radical retropubic prostatectomy [1-11].

This topic will discuss the innervation of the abdomen, indications, techniques and drugs used for some of these blocks, and complications specific to each block.

Equipment used, contraindications, and complications common to all nerve blocks are also discussed separately. (See "Overview of peripheral nerve blocks".)

Lower thoracic intercostal nerve or fascial plane blocks (such as erector spinae plane blocks) can be used for upper abdominal procedures (eg, cholecystectomy, subcostal incisions). (See "Thoracic nerve block techniques", section on 'Intercostal nerve block' and "Erector spinae plane block procedure guide".)

ANATOMY — The sensory supply of the skin, muscles, and parietal peritoneum of the anterolateral abdominal wall is derived from ventral rami of the thoracoabdominal intercostal nerves (ie, T7 to T11), the subcostal nerve (T12), and the L1 spinal nerve. The ilioinguinal (II) and iliohypogastric (IH) nerves arise from the lumbar plexus (L1) and provide sensory cutaneous innervation in the groin, upper hip, and thigh (figure 1 and figure 2). Cutaneous branches of all of these nerves travel variably through the transversus abdominis (TA) and internal oblique (IO) muscles and course within the transversus abdominis plane (TAP) [2-4]. At the lateral edge of the rectus muscle near the linea semilunaris, the anterior cutaneous branches gather posterior to the rectus muscle, pierce through the muscle, and terminate at the umbilicus and anterior abdominal wall [12,13]. (See "Anatomy of the abdominal wall", section on 'Nerves'.)

The fascial layers in the abdomen are essential to the performance of the abdominal nerve blocks. The planes between the TA and IO muscles, between the rectus muscle and its sheath, and between the transversalis fascia and quadratus lumborum muscle are target sites for deposition of local anesthetic (LA).

The peritoneum and bowel lie deep to the rectus sheath and the IO muscle and must be avoided during block placement.

The triangle of Petit, or lower lumbar triangle, refers to the section of the abdominal wall bounded by the iliac crest, the posterior margin of the external oblique muscle, and the lateral margin of the latissimus dorsi muscle. The floor of the triangle is formed by the IO muscle, and the TA muscle inserts on the inner lip of the iliac crest.

TRANSVERSUS ABDOMINIS PLANE (TAP) BLOCKS — The transversus abdominis plane (TAP) block (also called the lateral TAP block) is a fascial plane block performed by injecting local anesthetic (LA) in the plane between transversus abdominis (TA) and internal oblique (IO) muscles, or in the case of subcostal TAP block, between the TA muscle and the posterior sheath of the rectus abdominis (RA) muscle. Techniques for lateral and subcostal TAP blocks are discussed in detail separately. (See "Transversus abdominis plane (TAP) blocks procedure guide".)

RECTUS SHEATH BLOCK — The rectus sheath block involves injection of local anesthetic (LA) between the rectus abdominis (RA) muscle and the posterior rectus muscle sheath (figure 3 and figure 4 and image 1).

Clinical applications — This block may provide analgesia of the midline anterior abdominal wall from the xiphoid process to the pubic symphysis. Bilateral block can be particularly useful for umbilical surgery and for umbilical laparoscopy port incisions for children and adults [14-16]. Continuous rectus sheath block has also been used for analgesia after midline vertical or paramedian abdominal incisions [17,18].

Rectus sheath block technique — We perform rectus sheath blocks with ultrasound guidance. Ultrasound guidance may increase the success rate of rectus sheath block compared with an anatomic approach and may reduce the incidence of complications [19].

We perform the rectus sheath block at the upper, more cephalad third of the rectus muscle. At this level, the transversus abdominis (TA) muscle extends medially between the RA muscle and the peritoneum, and provides a buffer of safety between the needle target (the posterior rectus sheath) and the peritoneum. If the block is performed at the level of the umbilicus, the peritoneum lies directly below the posterior rectus sheath.

The following procedure is performed with the patient in a supine position:

●Place a high-frequency (ie, 5- to 10-MHz) ultrasound transducer in a transverse orientation below the costal margin on the lateral edge of the rectus muscle. Visualize the rectus muscle, the posterior rectus sheath, and the TA muscle below the rectus sheath (image 1).

●With the rectus muscle, sheath, and TA muscle in view, insert a 22-gauge, short-bevel, 50- to 100-mm needle in plane (picture 1 and figure 4) and in a lateral-to-medial direction through the muscle, entering the muscle at its very lateral border. Place the tip between the muscle body and the posterior sheath (image 2).

●Make sure that the needle tip is well visualized during advancement into the rectus muscle. As the needle tip approaches the posterior body of the muscle, inject small volumes of LA to confirm the needle tip on ultrasound.

●After negative aspiration, inject 20 mL of LA in 5-mL increments, aspirating gently between injections. Separation of the sheath from the muscle body should be visualized as LA is injected. The muscle is displaced superficially and the TA muscle is displaced downward. LA extends in cephalad and caudad directions within the sheath. This LA spreading pattern can usually be confirmed by sliding the transducer in a head-to-foot direction.

●Repeat the block on the other side as necessary [20].

Continuous rectus sheath block — Catheters may be placed for continuous postoperative rectus sheath block. Bilateral catheters are required, and they must be placed postoperatively to avoid intraoperative catheter damage or displacement [20]. The technique for needle placement for continuous block is similar to single-injection block, though an 18 to 20 gauge Touhy needle is used instead of a block needle. An example of continuous block technique is discussed separately. (See "Transversus abdominis plane (TAP) blocks procedure guide", section on 'Continuous TAP block'.)

ILIOINGUINAL AND ILIOHYPOGASTRIC NERVE BLOCK — The ilioinguinal (II) and iliohypogastric (IH) nerves are blocked together with a targeted injection of local anesthetic (LA) within the transversus abdominis plane (TAP). This block is useful for postoperative analgesia after inguinal hernia repair for children and adults (figure 2) [11,21,22].

Ilioinguinal and iliohypogastric block technique — The patient is positioned supine. The block is performed with ultrasound guidance using the following technique:

●Place a linear ultrasound transducer (6- to 18-MHz) cephalad and medial to the anterior superior iliac spine, oriented along a line between the anterior superior iliac spine (ASIS) and the umbilicus (figure 5). Visualize the external oblique, internal oblique (IO), and transversus abdominis (TA) muscles (image 3). The II and IH nerves may appear as echogenic (ie, they appear white) structures within the fascial plane between the IO and TA muscles. The deep circumflex iliac artery, or a branch of it, may be seen with the nerves. The II and IH nerves are usually visualized as one or two structures. However, depending on the position of the transducer and the patient's anatomy, the nerves may not be visible at all, in which case block success requires spread of the LA in the TAP.

●Insert a 50- to 100-mm, 22-gauge needle in plane (picture 1) in a medial-to-lateral direction. Place the needle tip near the II and IH nerves. A pop may be felt as the needle pierces the posterior IO fascia.

●After negative aspiration, inject 10 mL of LA in 5-mL increments, with gentle aspiration between [13,23].

TRANSVERSALIS FASCIA PLANE BLOCK — The transversalis fascia plane block is a posterior version of the ilioinguinal (II) and iliohypogastric (IH) block; ultrasound is used to identify the posterior tail of the transversus abdominis (TA) muscle, aiming for the origins of the II and IH nerves. This block targets branches of T12 and L1 in the plane between the TA muscle and the deeper transversalis fascia [24]. This block is in the same contiguous fascial plane as the lateral quadratus lumborum block (see 'Quadratus lumborum block' below). It is useful for analgesia for anterior iliac crest bone graft harvest.

Technique — The patient is positioned supine. This block is performed with ultrasound guidance, as follows:

●Place a linear ultrasound transducer (6- to 18-MHz) cephalad and medial to the anterior superior iliac spine, oriented along a line between the ASIS and the umbilicus, as for the II and IH block (figure 5 and image 3). Identify the external oblique, internal oblique (IO), and TA muscles, and trace them laterally until a tail is seen where the TA merges with the IO, becoming the transversalis fascia (image 4). The quadratus lumborum (QL) muscle is identified deep to the transversalis fascia [24,25].

●Insert a 22-gauge, 100- to 150-mm needle in plane (picture 1) in a medial-to-lateral direction. Place the needle tip deep to the transversalis fascia, anterior to the QL muscle.

●After negative aspiration, inject 10 to 20 mL of local anesthetic (LA) in 5-mL increments, with gentle aspiration between injections. Expansion of the space should be visualized as LA is injected [24,25].

QUADRATUS LUMBORUM BLOCK — The various quadratus lumborum (QL) blocks are fascial plane blocks performed by injecting local anesthetic (LA) in planes around the QL muscle. Techniques for QL blocks are discussed in detail separately. (See "Quadratus lumborum block procedure guide".)

LOCAL ANESTHETIC CHOICE — Abdominal nerve blocks are usually performed for postoperative pain control. Thus, long-acting local anesthetics (LAs) such as ropivacaine (0.25 or 0.375%) or bupivacaine (0.25 or 0.375%) are usually administered for these blocks. (See "Overview of peripheral nerve blocks", section on 'Drugs'.)

COMPLICATIONS — A number of complications have been reported with abdominal nerve blocks, including bowel perforation and hematoma, liver laceration, retroperitoneal hematoma, and transient femoral nerve palsy [26-33]. We suggest ultrasound guidance rather than anatomic landmark techniques for abdominal blocks to increase the success rate and decrease the incidence of vascular, peritoneal, and organ puncture. (See "Overview of peripheral nerve blocks", section on 'Block guidance techniques'.)

There are limited published complications of quadratus lumborum (QL) blocks. Several reported complications have likely related to paravertebral or epidural spread, including cases of hypotension [34,35] and a case of unilateral hip flexion weakness after a QL1 block [36].

The fascial plane blocks are associated with a higher risk of local anesthetic systemic toxicity than many other peripheral nerve blocks. This issue is discussed separately. (See "Local anesthetic systemic toxicity", section on 'Block site'.)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Local and regional anesthesia" and "Society guideline links: Local anesthetic systemic toxicity".)

SUMMARY AND RECOMMENDATIONS

●Uses – The abdominal fascial plane blocks can be used for anesthesia and/or analgesia for abdominal procedures. (See 'Introduction' above and 'Quadratus lumborum block' above.)

●Ultrasound guidance – We suggest using ultrasound guidance rather than anatomic landmarks to perform abdominal blocks (Grade 2C) to increase the success rate and reduce complications. (See "Overview of peripheral nerve blocks", section on 'Block guidance techniques'.)

●Individual blocks

•Transverse abdominis plane (TAP) block, subcostal TAP block, and ilioinguinal (II) and iliohypogastric (IH) nerve blocks are abdominal blocks performed by injection of local anesthetic (LA) into the TAP and are used for analgesia for open and laparoscopic abdominal surgery. (See "Transversus abdominis plane (TAP) blocks procedure guide" and 'Ilioinguinal and iliohypogastric nerve block' above.)

•Rectus sheath block is performed by injection of LA between the body of the rectus muscle and its posterior sheath. It is used for midline, periumbilical surgery. (See 'Rectus sheath block' above.)

•Transversalis fascia plane block is performed by injection of LA between the transversalis fascia and the quadratus lumborum (QL) muscle. It is particularly useful for analgesia after iliac crest bone graft harvest. (See 'Transversalis fascia plane block' above.)

•A QL block may be a better alternative to other abdominal wall blocks (TAP and II/IH) with potentially greater dermatomal coverage, and possibly some visceral analgesia as well. (See "Quadratus lumborum block procedure guide".)

●Continuous block – Perineural catheters may be placed for continuous infusion of LA for postoperative pain for TAP blocks and rectus sheath blocks. (See 'Continuous rectus sheath block' above and "Transversus abdominis plane (TAP) blocks procedure guide", section on 'Continuous TAP block'.)

●Complications – Complications have rarely been reported with abdominal nerve blocks include bowel perforation and hematoma, liver laceration, retroperitoneal hematoma, and transient femoral nerve palsy. (See 'Complications' above.)