A broad spectrum of diseases mimicking appendicitis was detected using graded compression in 977 true-negative patients in respect to acute appendicitis. Among these, mesenteric lymphadenitis was the only US diagnosis in 265 patients (222 patients were younger than 16 years), mesenteric lymphadenitis combined with terminal ileitis and/or ileocaecitis was observed in 99 patients (among these, 73 were younger than 16 years), in 4 cases the reason for symptoms was Crohn’s disease, intestinal inflammation resembling Crohn’s disease was observed in 34 patients. Caecal diverticulitis was detected in 3 cases, omental infarction and epiploic appendicitis in one case each.

        Key words: ultrasound - ultrasonography - acute appendicitis - acute abdomen - alternative diagno- sis - mesenteric lymphadenitis - terminal ileitis and ileocaecitis