Description

Test Criteria

The appendix is a worm-like extension of the cecum and, for this reason, has been called the vermiform appendix. The average length of the appendix is 8-10 cm (range 2-20 cm). The normal appendix consists of 5 distinct layers; the inner most echogenic layer which represents the interface of mucosa and lumen, the hypoechoic mucosal layer, the echogenic submucosal layer, the hypoechoic muscularis propria layer and the outermost echogenic serosal layer. The typical normal appendix in children has an inner hypoechoic band without folding (Figure  and this feature is a distinguishable finding from other bowel structures. Therefore, recognition of this finding reduces the time and effort involved in identifying normal appendix and confidently excluding acute appendicitis. This inner hypoechoic band corresponds to the mucosal layer with abundant lymphoid tissue on histologic examination and disappears with aging