title: The 5-tier system of assessing fetal heart rate tracings is superior to the 3-tier system in identifying fetal acidemia.
abstract: OBJECTIVE
  Electronic fetal heart rate monitoring was developed to identify fetuses at risk of acidemia for intervention before adverse outcomes. Our objective was to compare the 3-tier system with a 5-tier system in evaluation of fetal acidemia.
  
  
  METHODS
  Retrospective case-control study of patients with a fetal arterial pH <7 matched to the next birth that resulted in a pH >7.2. Tracings were categorized into 3- and 5-tier systems by a single reviewer. Sensitivities and specificities were calculated for each.
  
  
  RESULTS
  Twenty-four cases and 24 controls were identified. The sensitivity for an orange or red tracing was higher than for category III, with more of these in the pH <7 group compared with controls (P ≤ .001). There were significantly more green, blue, and yellow tracings in the normal pH group compared with the pH <7 group (P = .033, P = .008, P = .023), respectively.
  
  
  CONCLUSIONS
  The 5-tier system had a better sensitivity than the 3-tier system.
authors.affiliation: Department of Obstetrics and Gynecology, Columbia University Medical Center, New York, NY, USA.
authors.forename: Jaclyn
authors.initials: J
authors.lastname: Coletta
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Murphy
authors.forename: Zachary
authors.initials: Z
authors.lastname: Rubeo
authors.forename: Cynthia
authors.initials: C
authors.lastname: Gyamfi-Bannerman
mesh_terms: D000138:Acidosis / Q000175:diagnosis*; D000328:Adult; D005260:Female; D005323:Fetal Monitoring / Q000379:methods*; D006340:Heart Rate, Fetal / Q000502:physiology*; D006801:Humans; D011247:Pregnancy; D012189:Retrospective Studies; D012680:Sensitivity and Specificity