LAUSR

The coiled spring sign refers to the double contrast enema (DCE) appearance of appendiceal intussusception into the cecum, which is best seen en face. There is nonfilling of the appendix with barium, and thin concentric rings of barium radiate outward from the appendix base, (Fig. 1) giving a spring-like appearance (Fig. 2). The invaginated appendix is thought to act as a lead point producing a variable degree of cecocecal intussusception, with barium being trapped in mucosal folds between the intussusceptum and intussuscipiens [1]. Occasionally, the intussusception may be reduced entirely during the barium exam [1]. This characteristic radiologic appearance of appendiceal intussusception was first described by Artner in 1929 [2] although the phenomenon of appendiceal intussusception has been known since 1858 when McKidd reported a case in a 7-year-old child [3]. The incidence of appendiceal intussusception is very rare, occurring in 0.01% of cases in a 1963 review of 71,000 pathologic specimens [4]. Appendiceal intussusception can be idiopathic in asymptomatic patients but may also result from inflammation or from lead points due to endometriosis, mucocele, adenoma, adenocarcinoma, carcinoid, or an inverted appendiceal stump [5]. While the coiled spring appearance on DCE is a reliable sign of appendiceal intussusception, it is not possible to determine radiographically if the appearance is due to a pathologic process or if it is idiopathic [1]. Clinically, patients most often (63%) present with non-specific chronic waxing and waning symptoms for weeks to months, the most common being abdominal pain (78%), vomiting (26%), and blood per rectum (23%) [5].