title: Randomized controlled trial on timing and number of sampling for bile aspiration cytology.
abstract: BACKGROUND
  The issue on timing and number of bile sampling for exfoliative bile cytology is still unsettled.
  
  
  METHODS
  A total of 100 patients with cholangiocarcinoma undergoing resection after external biliary drainage were randomized into two groups: a 2-day group where bile was sampled five times per day for 2 days; and a 10-day group where bile was sampled once per day for 10 days (registered University Hospital Medical Information Network/ID 000005983). The outcome of 87 patients who underwent laparotomy was analyzed, 44 in the 2-day group and 43 in the 10-day group.
  
  
  RESULTS
  There were no significant differences in patient characteristics between the two groups. Positivity after one sampling session was significantly lower in the 2-day group than in the 10-day group (17.0 ± 3.7% vs. 20.7 ± 3.5%, P = 0.034). However, cumulative positivity curves were similar and overlapped each other between both groups. The final cumulative positivity by the 10th sampling session was 52.3% in the 2-day group and 51.2% in the 10-day group. We observed a small increase in cumulative positivity after the 5th or 6th session in both groups.
  
  
  CONCLUSIONS
  Bile cytology positivity is unlikely to be affected by sample time.
authors.affiliation: Division of Surgical Oncology, Department of Surgery, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 466-8550, Japan. nagino@med.nagoya-u.ac.jp.
authors.forename: Tomonori
authors.initials: T
authors.lastname: Tsuchiya
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Yokoyama
authors.forename: Tomoki
authors.initials: T
authors.lastname: Ebata
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Igami
authors.forename: Gen
authors.initials: G
authors.lastname: Sugawara
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Kato
authors.forename: Yoshie
authors.initials: Y
authors.lastname: Shimoyama
authors.forename: Masato
authors.initials: M
authors.lastname: Nagino
mesh_terms: D000328:Adult; D000368:Aged; D001646:Bile / Q000166:cytology*; D001650:Bile Duct Neoplasms / Q000473:pathology* / Q000601:surgery; D001653:Bile Ducts, Intrahepatic / Q000473:pathology*; D001662:Biliary Tract Surgical Procedures / Q000379:methods; D018281:Cholangiocarcinoma / Q000473:pathology* / Q000601:surgery; D003581:Cytodiagnosis / Q000379:methods; D004322:Drainage / Q000379:methods / Q000706:statistics & numerical data*; D006801:Humans; D007813:Laparotomy / Q000379:methods; D008875:Middle Aged; D011379:Prognosis; D012680:Sensitivity and Specificity; D013997:Time Factors
keywords: Aspiration cytology; Bile; Cholangiocarcinoma