title: The umbilicus: a reliable surface landmark for the aortic bifurcation?
abstract: OBJECTIVE
  Anatomical surface landmarks are frequently used by clinicians to guide both diagnosis and treatment. Few studies have examined the reliability of vascular anatomical landmarks in living subjects. The umbilicus has traditionally been described as a surface landmark for the bifurcation of the abdominal aorta. This study examined the factors affecting the position of the umbilicus relative to that of the aortic bifurcation in 95 patients.
  
  
  METHODS
  106 consecutive abdominal CT scans were analysed by a surgeon and radiologist. Following exclusion of CT scans with relevant significant intra-abdominal pathology, 95 patients were included in the study. Measurements were taken of the craniocaudal distance between the aortic bifurcation and umbilicus, as well as maximum subcutaneous fat thickness at the level of the umbilicus. Patient age and gender were also documented.
  
  
  RESULTS
  The umbilicus was found to lie -6.3 ± 26.5 mm from the aortic bifurcation. Increasing subcutaneous fat thickness was associated with a more caudal position of the umbilicus relative to the aortic bifurcation. This result was highly statistically significant in males over 65 years old.
  
  
  CONCLUSIONS
  This study suggests that the umbilicus is a reliable clinical surface landmark for the bifurcation of the abdominal aorta. Whilst some variation in craniocaudal distance exists between patients, in the majority of cases, the bifurcation of the abdominal aorta lies within a clinically narrow range of distances from the umbilicus.
authors.affiliation: Basildon and Thurrock University Hospitals, Basildon, Essex, SS16 5NL, UK. lukas.attwell@doctors.org.uk.
authors.forename: Lukas
authors.initials: L
authors.lastname: Attwell
authors.affiliation: Royal Free Hospital, Pond Street, London, NW3 2QG, UK.
authors.forename: Sarah
authors.initials: S
authors.lastname: Rosen
authors.affiliation: Basildon and Thurrock University Hospitals, Basildon, Essex, SS16 5NL, UK.
authors.forename: Bhavin
authors.initials: B
authors.lastname: Upadhyay
authors.affiliation: Royal Free Hospital, Pond Street, London, NW3 2QG, UK.
authors.forename: Peter
authors.initials: P
authors.lastname: Gogalniceanu
mesh_terms: D000368:Aged; D001012:Aorta, Abdominal / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed; D014472:Umbilicus / Q000000981:diagnostic imaging*
keywords: Abdominal aorta; Aortic bifurcation; Surface anatomy; Vascular