Transversalis fascia plane block is useful in the evaluation and management of lateral subcostal abdominal and groin pain. The technique also is useful to provide surgical anesthesia for iliac crest bone harvest, appendectomy, cecostomy, and inguinal hernia repair (Fig. 99.1). It may serve as an adjunct to transversus abdominis plane block if more lateral anesthesia is required. Transversalis fascia plane block with local anesthetics can be used diagnostically during differential neural blockade on an anatomic basis in the evaluation of lateral subcostal abdominal pain groin to help distinguish abdominal wall pain from pain emanating from more the proximal T12 and L1 nerves and the ilioinguinal and iliohypogastric nerves.

Transversalis fascia plane block with local anesthetic may be used for palliation in acute pain emergencies, including postoperative pain relief following lateral abdominal and groin surgery including iliac crest bone harvest and inguinal hernia repair as well as postcesarean section pain, during the wait for pharmacologic therapies to take effect. Transversalis fascia plane block with local anesthetic and steroids also is useful in the treatment of persistent pain after lateral abdominal and inguinal surgery or abdominal wall trauma when the pain is thought to be secondary to inflammation. Pain of malignant origin involving the lateral abdominal wall and groin has been successfully managed by the placement of a catheter for continuous infusions of local anesthetics using this ultrasound-guided technique.

The primary target of the transversalis fascia plane block is the anterior and lateral cutaneous branches of the T12 and L1 intercostal nerves. The anatomic basis of the transversalis fascia plane block is the fact that the local anesthetic injected under ultrasound guidance between the deep fascia of the transversus abdominis muscle and the deep transversalis fascia will spread along the inner surface of the quadratus lumborum muscle and block the more proximal portions of the T12 and L1 nerves (Fig. 99.2). When these nerves are blocked at this more proximal point along their paths, both the lateral and anterior cutaneous branches of these nerves will be blocked in contradistinction to transversus abdominis plane block, which usually blocks only the anterior branches of these nerves. By blocking the more proximal lateral branches, the subcostal, iliohypogastric, and ilioinguinal nerves will be blocked (see Fig. 99.3).

Ultrasound-guided transversalis fascia plane block is performed with the patient facing the operator in the lateral decubitus position with the side to be blocked on top (Fig. 99.4). When treating ilioinguinal or iliohypogastric nerve entrapment, placing a pillow between the patient’s flexed knees may make the patient more comfortable by taking tension off the entrapped nerve.