title: Estimating blood loss: can teaching significantly improve visual estimation?
abstract: OBJECTIVE
  Visually estimated blood loss has long been known to be imprecise, inaccurate, and often underestimated, which may lead to delayed diagnosis and treatment. Our purpose is to determine whether a brief didactic course can improve visually estimated blood loss and whether prior clinical experience influences estimation of blood loss.
  
  
  METHODS
  Reconstituted whole blood was obtained from the blood bank, and simulated scenarios with known measured blood loss were created using common surgical materials. Visually estimated blood loss was performed by medical personnel before and after a 20-minute didactic session. Percent errors of estimated blood loss were calculated and comparisons were made before and after the lecture. The effects of actual blood volume and clinical experience on estimation of blood loss were assessed.
  
  
  RESULTS
  A total of 53 participants assessed 7 scenarios. There were significant reductions in error for all scenarios. Median percent error in estimated blood loss was not influenced by clinical experience, either before or after the didactic session. Blood loss tends to be overestimated at low volumes and underestimated at high volumes.
  
  
  CONCLUSIONS
  Error in estimating blood loss is dependent on actual blood loss volume. Medical students and experienced faculty demonstrate similar errors, and both can be improved significantly with limited instruction. This educational process may assist clinicians in everyday practice to more accurately estimate blood loss and recognize patients at risk for hemorrhage-related complications.
authors.affiliation: Department of Obstetrics & Gynecology, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112-2822, USA. gdildy3@lsuhsc.edu
authors.forename: Gary A
authors.initials: GA
authors.lastname: Dildy
authors.forename: Archana R
authors.initials: AR
authors.lastname: Paine
authors.forename: Natalie C
authors.initials: NC
authors.lastname: George
authors.forename: Cruz
authors.initials: C
authors.lastname: Velasco
mesh_terms: D004501:Education, Medical; D004521:Educational Measurement; D006470:Hemorrhage / Q000175:diagnosis*; D006801:Humans