[Sonography of acute appencitis and the main differential diagnoses].

Today sonography is the first line imaging method for diagnosing acute appendicitis. Experienced investigators will have an accuracy of more than 90%. Sonography can diagnose many conservatively managed diseases. The most important differential diagnoses are infectious ileocoecitis, right sided diverticulitis, appendagitis, adnexitis, ruptured or torque ovarian cysts, ectopic pregnancies. Ureterolithiasis, cholecystitis, haematomas in the psoas muscle or in the rectus muscle are rarer causes of right lower quadrant pain. Sonography can reduce the high rate of false positive clinical examinations concerning acute appendicitis. It has to be stated that an exclusion of appendicitis can only be made sonographically if the normal appendix can be seen in its full length and/or an other differential diagnosis can be depicted that explains the clinical symptoms. Mucoceles are rare cystoid lesions of the appendix. They exhibit a typical onion skin sign structure caused by different mucus viscosities. In large mucoceles a tumor causes this lesion.