Rationale: To assess the importance of the new radiographic sign of faecal loading in the cecum for the diagnosis of acute appendicitis, in comparison with other inflammatory diseases, and to verify the maintenance of this radiographic sign after surgical treatment of appendicitis.

Methods: 470 consecutive patients admitted to the hospital due to acute abdomen were prospectively studied: Group 1 [n=170] – diagnosed with acute appendicitis, subdivided into: Subgroup 1A – [n=100] – submitted to an abdominal radiographic study before surgical treatment, Subgroup 1B – [n=70] – patients who had plain abdominal X-rays done before the surgical procedure and also the following day; Group 2 [n=100] – right nephrolithiasis; Group 3 [n=100] – right acute inflammatory pelvic disease; Group 4 [n=100] – acute cholecystitis. The patients of Groups 2,3 and 4 were submitted to abdominal radiography during the pain episode.

Results: The sign of faecal loading in the cecum, characterized by hypo transparency interspersed with multiple small foci of hyper transparent images, was present in 97 patients of Subgroup 1A, in 68 patients of Subgroup 1B, in 19 patients of Group 2, in 12 patients of Group 3 and in 13 patients of Group 4. During the postoperative period the radiographic sign disappeared in 66 of the 68 cases that had presented with the sign. The sensitivity of the radiographic sign for acute appendicitis was 97.05% and its specificity was 85.33%. The positive predictive value for acute appendicitis was 78.94% and its negative predictive value was 98. 08%.

Discussion: The radiographic image of faecal loading in the cecum is associated with acute appendicitis and disappears after appendectomy. This sign is uncommon in other acute inflammatory diseases of the right side of the abdomen.