Normal gas-filled appendix simulating biliary-tree air in a case of acute cholecystitis.

Abstract

The roentgen sign of air in the biliary tree in the presence of acute abdominal symptoms is generally recognized as indicating a fistulous connection with the intestinal tract (2, 6). Among the conditions included in differential diagnosis, air in the appendix is rarely mentioned. Our case is unusual in that air appeared in a malpositioned, noninflamed appendix which lay in the right upper quadrant of a patient with acute cholecystitis. Case Report A 68-year-old man was admitted to another hospital with right upper quadrant pain and vomiting of bile-like fluid following a rich meal. He had previously had no gastrointestinal tract symptoms. An oral cholecystogram showed no function, but a lucent shadow in the right upper quadrant was interpreted as air in the common duct, suggesting the diagnosis of spontaneous internal biliary fistula (Fig. 1). Following admission to the Hitchcock Hospital, Hanover, N. H., one month later, repeat cholecystography again showed no function and a similar lucent shadow. At this time, the patient was asymptomatic with normal findings on physical examination and laboratory studies. A gastrointestinal series was negative. A barium-enema examination, however, revealed a malrotated cecum in the right upper quadrant, with the appendix coming off superiorly and lying in the same position as the previously described lucent shadow. An intravenous cholangiogram confirmed these findings. The air-filled appendix, with barium in its tip, was seen lying parallel to and near the opacified common duct (Fig. 2). Once again the gallbladder was not visualized. At surgery a freely movable, normal appendix, 6 cm in length, was found in the right upper quadrant. The gallbladder was thickwalled and contained four stones, but showed no evidence of fistula. Discussion Air in the biliary tree is a well known roentgenographic sign of spontaneous internal biliary fistula (2, 6). It usually consists of a lucent branching or Y-shaped shadow which widens as it approaches the porta hepatis. It may be visible in the erect but not in the supine position, although it is usually seen in both (4). Frimann-Dahl emphasizes that it may be seen only in the left lateral decubitus position and advocates this view when the condition is suspected but is not seen on the conventional films (2). The duct may be only partially filled with air, and sometimes no branching or Y configuration is visible. The differential diagnosis includes air in bowel, in skin folds, in gallbladder, and in abscesses as well as perirenal fat outlines and portal vein gas (4). A normally positioned appendix is rarely gas-filled unless it is acutely inflamed (1, 3). When the cecum fails to descend and remains in the right upper quadrant, however, the appendix often represents the highest point in the right colon, and any gas in the cecum or ascending colon rises and fills it, especially when the patient is in the upright position (5).