Ultrasound-guided transversus abdominus plan block for the management of abdominal pain: An alternative to differential epidural block

The abdominal wall consists of three muscle layers—the external oblique, the internal oblique, and the transversus abdominus—and their associated fascial sheaths. The neuronal afferents course through the neurofascial plane between the internal and the transversus abdominus muscles—the “transversus abdominus plane” (TAP). The TAP block is used to produce a dermatomal sensory block of the lower six thoracic and upper lumbar abdominal afferents. It was shown to be effective in providing postoperative analgesia after various lower abdominal procedures, mainly radical prostatectomy, large bowel resections, and gynecologic procedures as well as cesarean sections. The recent introduction of ultrasound (US) to different regional anesthesia procedures allows more accurate and safer performance of peripheral nerve blocks. With US imaging, the muscle layers are visible from the rectus medially through the aponeurotic area at the edge of the rectus to the three distinct layers of external, internal oblique, and transversus abdominus in the lateral abdominal wall. Installation of local anesthetics in this plane anesthetizes the anterior abdominal wall on this side. This block can be used as a diagnostic tool or as a therapeutic modality via a continuous indwelling catheter for postoperative lower abdominal pain or chronic pain syndromes arising from the anterior abdominal wall.

Keywords: TAP, Continuous catheter, Ultrasound, Postoperative chronic pain, Abdominal pain, Differential block