title: Shrinkage revisited:  how long is long enough?
abstract: OBJECTIVE
  Temporal artery biopsy (TAB) is considered the gold standard in the diagnosis of suspected giant cell arteritis. The most commonly accepted length for an adequate postfixation TAB specimen is 20 mm. There is a reported 2.4-mm mean shrinkage with the fixation process, but to date, there is no data correlating shrinkage after specimen fixation with the biopsy results.
  
  
  METHODS
  A prospective, Institutional Review Board-approved study of all patients undergoing TAB over 1 year was performed. The pre- and postfixation measurements were recorded. Comparison of the pre- and postfixation lengths was performed, and potential correlation was sought with biopsy results and patient gender, age, and race/ethnicity.
  
  
  RESULTS
  Sixty-two TABs were performed over a 1 year period with 53 (85.5%) negative for giant cell arteritis. The mean shrinkage length was 4.61 mm ± 2.97 overall, and the amount of shrinkage between positive and negative TAB specimens was not significant (p = 0.43). Linear regression analysis did not show any correlation between the amount of shrinkage and the length of the specimen or duration in fixative. There was no significant difference between the amount of shrinkage by surgeon (p = 0.82), patient gender (p = 1.00), or race/ethnicity (p = 0.695).
  
  
  CONCLUSIONS
  Surgeons should be aware of the amount of shrinkage of TAB specimens to meet the commonly accepted goal of 20 mm postfixation length. Based on the 4.61-mm mean shrinkage with 2.97-mm standard deviation, a 27.58-mm specimen would have to be obtained to reach the 20-mm goal. Surgeon, patient age, gender, race/ethnicity, and biopsy results did not have a significant impact on the amount of TAB specimen shrinkage.
authors.affiliation: Wills Eye Emergency Room, Wills Eye Institute, Philadelphia, Pennsylvania 19107, USA. amurchison@willseye.org
authors.forename: Ann P
authors.initials: AP
authors.lastname: Murchison
authors.forename: Jurij R
authors.initials: JR
authors.lastname: Bilyk
authors.forename: Ralph C
authors.initials: RC
authors.lastname: Eagle
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Savino
mesh_terms: D000367:Age Factors; D001706:Biopsy; D005006:Ethnicity; D005260:Female; D005404:Fixatives; D013700:Giant Cell Arteritis / Q000473:pathology*; D006801:Humans; D008297:Male; D011446:Prospective Studies; D012737:Sex Factors; D013048:Specimen Handling; D013699:Temporal Arteries / Q000473:pathology*; D016707:Tissue Fixation
chemical_list: D005404:Fixatives