Figure 4.

Ultrasound visualization of rectus sheath block (CEUS and B-mode). (A) before RSB: Prior to the block, the rectus abdominis muscle, its sheath, the peritoneum, and intra-abdominal structures are well visualized. (B) during RSB: Perflubutane within the needle lumen is clearly visualized in CEUS mode. (C) after RSB: The local anesthetic (LA) appears as a hyperechoic area in CEUS mode and as a hypoechoic area in B-mode. (D) 5 minutes after RSB: LA is clearly delineated in CEUS mode. In B-mode, the spread of LA is not visualized.(Reproduced from Onishi et al²³ © Springer Nature. Published with permission under STM Permissions Guidelines).

Abbreviations: RSB, rectus sheath block; CEUS, contrast-enhanced ultrasonography; LA, local anesthetic.