title: Preoperative laboratory evaluation of patients aged over 40 years undergoing elective non-cardiac surgery.
abstract: OBJECTIVE
  Although it is generally agreed that a medical history and physical examination should be obtained as part of preoperative evaluation, there is still substantial controversy about the additional benefits of preoperative screening tests. The objective of the present study was to determine the percentage of abnormalities on laboratory tests among a population that underwent non-cardiac surgery and to correlate these tests with changes in preoperative evaluation management.
  
  
  METHODS
  Cross-sectional study, carried out in a University Hospital.
  
  
  METHODS
  991 patients aged over 40 years undergoing elective non-cardiac surgery from July 1997 to January 2000 were studied. Blood cell count, serum sodium, potassium, urea and creatinine, prothrombin, thrombin and partial thromboplastin time, electrocardiogram and chest X-ray were evaluated.
  
  
  RESULTS
  Out of the 957 electrocardiograms performed, some type of abnormality was found in 504 cases (50.9%) and, among the 646 chest X-rays requested, 271 (42.0%) displayed alterations. Laboratory tests showed abnormal values ranging from 5.1% (prothrombin time) to 41.0% (hematocrit). Increased percentages of abnormal tests with increasing patient age were also observed.
  
  
  CONCLUSIONS
  Although there were substantial numbers of screening test abnormalities in preoperative evaluations, these results seldom interfered in patient management.
authors.affiliation: Department of Medicine, School of Medicine, Universidade de São Paulo, Av. Dr. Arnaldo 455, São Paulo, Brazil CEP 01246-903.
authors.forename: Fábio Yoshito
authors.initials: FY
authors.lastname: Ajimura
authors.forename: Alex Silva Santos Freire
authors.initials: AS
authors.lastname: Maia
authors.forename: Adriana
authors.initials: A
authors.lastname: Hachiya
authors.forename: Alexandra Sayuri
authors.initials: AS
authors.lastname: Watanabe
authors.forename: Maria do Patrocínio Tenório
authors.initials: Mdo P
authors.lastname: Nunes
authors.forename: Mílton de Arruda
authors.initials: Mde A
authors.lastname: Martins
authors.forename: Fábio Santana
authors.initials: FS
authors.lastname: Machado
mesh_terms: D000328:Adult; D000367:Age Factors; D001774:Blood Chemical Analysis; D001780:Blood Coagulation Tests; D003430:Cross-Sectional Studies; D003955:Diagnostic Tests, Routine / Q000706:statistics & numerical data*; D017558:Elective Surgical Procedures; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011300:Preoperative Care / Q000379:methods*; D013902:Radiography, Thoracic