[Importance of the radiographic sign of fecal loading in the cecum for the differential diagnosis of acute appendicitis]

Abstract

Background: Although the radiographic characteristics of acute appendicitis have been well documented, the value of plain abdominal radiography has not been completely studied. Therefore, the purpose of this investigation was to verify a new radiographic sign: the presence of fecal loading in the cecum.

Methods: 470 consecutive patients of both sexes were admitted to the hospital due to acute abdomen and pain localized in the right flank were studied prospectively. The patients were divided into four groups: Group 1 (n = 170) - diagnosed with acute appendicitis and subdivided into two subgroups: Subgroup 1A - (n = 100) - patients submitted to an abdominal radiographic study a few hours before surgical treatment, Subgroup 1B - (n = 70) - patients submitted to two abdominal radiographic studies, one before the surgical procedure and the other the following day; Group 2 (n = 100) -patients of both sexes with right nephrolithiasis submitted to an abdominal radiography during the episode of pain caused by the lithiasis; Group 3 (n = 100) - women diagnosed with right acute inflammatory pelvic disease that underwent an abdominal radiographic study during the pain incident; Group 4 (n = 100) - patients of both sexes operated upon to treat acute cholecystitis submitted to abdominal radiography during the pain episode that preceded the surgical procedure. All of the radiographs were plain with an anteroposterior view of the abdomen.

Results: The sign of fecal loading in the cecum 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%.

Conclusions: The radiographic image of fecal loading in the cecum is associated with acute appendicitis. The image usually disappears soon after the appendix is removed. This sign is uncommon in other acute inflammatory diseases of the right side of the abdomen. When a diagnosis of acute appendicitis is suspected, the absence of this sign indicates great possibility of a different diagnosis.