title: [Ultrasonography of the normal vermiform appendix].
abstract: OBJECTIVE
  To study the detectability and the appearance of the vermiform appendix with ultrasound in asymptomatic adults.
  
  
  METHODS
  A prospective study was performed on 300 patients, selected without regard to age, sex and weight. We tried to visualize the appendix with a 3.5 MHz annular array and a 5 MHz linear array transducer.
  
  
  RESULTS
  In 63% of the patients the appendix was clearly visualised. The main reasons for non-visualisation were obesity with insufficient ultrasound penetration (38%) and the caecum laying in pelvic or atypical position (24%). In 31%, no cause was apparent but we assume that the appendix often lies behind the caecum. The sonographic image showed an aperistaltic target originating at the caecum, and ending blindly. In 42% of cases the appendix was ovoid in transverse section; in 32%, round; and in 26% both forms were found within one appendix. Intraluminal gas was visible in 86%. The mean transverse diameter was 5.2 mm (min. 3 mm, max. 13 mm) and in 76% the transverse diameter was lower than 6 mm.
  
  
  CONCLUSIONS
  The sonographic detectability, the appearance and the size of the normal appendix show considerable variations.
authors.affiliation: Abteilung für Röntgendiagnostik und Nuklearmedizin Krankenhaus der Barmherzigen Brüder in Salzburg.
authors.forename: T
authors.initials: T
authors.lastname: Rettenbacher
authors.forename: A
authors.initials: A
authors.lastname: Hollerweger
authors.forename: P
authors.initials: P
authors.lastname: Macheiner
authors.forename: N
authors.initials: N
authors.lastname: Gritzmann
mesh_terms: D000328:Adult; D000886:Anthropometry; D001064:Appendicitis / Q000000981:diagnostic imaging; D001065:Appendix / Q000000981:diagnostic imaging*; D005260:Female; D005740:Gases; D006801:Humans; D008297:Male; D011446:Prospective Studies; D012016:Reference Values; D014463:Ultrasonography
chemical_list: D005740:Gases