Introduction
Abdominal surgeries requiring extended midline incisions are associated with severe postoperative pain (1).
Postoperative pain was observed in 59 patients (40%) (95% CI = 39%-41%) hospitalized in the surgery departments (2).
Patients from surgical settings reported a high prevalence of pain providing evidence that pain management continues to be suboptimal. Over two‐thirds reported they had experienced pain during their hospital stay, around a quarter reported they had experienced pain for all or most of the time, and if patients in the latter group reported that pain experienced was usually severe, they were categorized as having severe and enduring pain, accounting for 12.3% (278) of the total sample (3).
Recent randomized clinical trials (RCT) evidence showed that ultrasound guided regional techniques or nervous blocks can offer an effective component of multimodal postoperative analgesia after a variety of surgeries with limited side-effects (4).
Bilateral rectus sheath block (RSB) can provide postoperative analgesia for procedure involving a midline incision with a slower absorption kinetics profile for local anesthetics than other compartment blocks (5). The rectus sheath block (RSB) is used to achieve operative muscle relaxation and analgesia (6).
Anatomically, the central portion of the anterior abdominal wall is innervated by the ventral branches of the T7–T11 spinal nerve roots; these ventral branches lie between the rectus abdominis muscle and the posterior rectus sheath, and enter the rectus muscle near the midline (7). As the tendinous intersections of the rectus muscle are not fused to the posterior rectus sheath, local anesthetic from a single injection site is able to spread cephalocaudally within this compartment (8).
The rectus sheath is formed from the aponeuroses of the fascial sheaths of all three lateral abdominal wall muscles (9). The external oblique, internal oblique, and transversus abdominis muscles each form a bilaminar aponeurosis at its medial border converging to form the lateral border of the rectus abdominis muscle, termed the linea semilunaris. The anterior and posterior lamina of the external oblique and the anterior lamina of internal oblique muscles fuse together and continue further medially over the ventral surface of the rectus abdominis muscle to form the anterior portion of the rectus sheath (9).
Like other central non-neuraxial regional anesthesia, blocks of the abdomen, RSB only provides analgesia for somatic pain, not pain of visceral origin (6).
In recent times, rectus sheath block is more commonly used in pediatric patients (10,11), but its efficacy has been demonstrated in adult patients (12).