title: Cardiotocographic findings in the second stage of labor among fetuses delivered with acidemia: a comparison of two classification systems.
abstract: BACKGROUND
  The RCOG classification system of CTG trace is widely used for the analysis of the fetal heart rate during the first and second stage of labor. Other authors proposed specific classification systems for the second stage traces.
  
  
  OBJECTIVE
  To evaluate the accuracy of RCOG and Piquard cardiotocographic patterns classification systems in predicting fetal acidemia in the second stage of labor.
  
  
  METHODS
  This was a nested retrospective case-control study including fetuses delivered with metabolic acidemia in the second stage of labor and a matched group of non-acidemic fetuses as controls. Cases and controls were selected from the electronic medical records of the University Hospital of Bologna between 2008 and 2013. The last 60min of the cardiotocograms recorded during the second stage of labor were independently classified by a senior consultant and a trainee according to RCOG and Piquard classifications. The inter-observer agreement and the accuracy of the two classifications in predicting fetal acidemia were evaluated.
  
  
  RESULTS
  In all, 82 acidemic fetuses and 164 controls were recruited in the study period. Regarding the CTG traces assessment, the inter-observer agreement was moderate for both the categorizations (RCOG κ=0.584). Unclassifiable CTG patterns were more frequent among acidemic fetuses vs controls either at RCOG and at Piquard evaluation (26.8% vs 7.9%, p<0.001). Both systems yielded a moderate and comparable ability to predict fetal acidemia (RCOG ROC AUC=0.731; 95% CI 0.660-0.795; Piquard ROC AUC=0.773; 95% CI 0.704-0.833. DeLong z-test=1.186, p=0.236).
  
  
  CONCLUSIONS
  RCOG and Piquard systems have a moderate accuracy in identifying acidemic fetuses during the second stage of labor. The occurrence of unclassifiable findings seems significantly more common among the acidemic fetuses.
authors.affiliation: Department of Obstetrics and Gynecology, University of Parma, Via Gramsci 14, 43126 Parma, Italy. Electronic address: tullioghi@yahoo.com.
authors.forename: Tullio
authors.initials: T
authors.lastname: Ghi
authors.affiliation: Department of Medicine and Surgery (DIMEC), Division of Obstetrics and Gynecology, University of Bologna, Via Massarenti 13, 40138 Bologna, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Morganelli
authors.affiliation: Department of Medicine and Surgery (DIMEC), Division of Obstetrics and Gynecology, University of Bologna, Via Massarenti 13, 40138 Bologna, Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Bellussi
authors.affiliation: Department of Biomedical and Neuromotor Sciences, Unit of Hygiene and Biostatistics, Via San Giacomo 12, 40126 Bologna, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Rucci
authors.affiliation: Department of Medicine and Surgery (DIMEC), Division of Obstetrics and Gynecology, University of Bologna, Via Massarenti 13, 40138 Bologna, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Giorgetta
authors.affiliation: Department of Medicine and Surgery (DIMEC), Division of Obstetrics and Gynecology, University of Bologna, Via Massarenti 13, 40138 Bologna, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Rizzo
authors.affiliation: Department of Obstetrics and Gynecology, University of Parma, Via Gramsci 14, 43126 Parma, Italy.
authors.forename: Tiziana
authors.initials: T
authors.lastname: Frusca
authors.affiliation: Department of Medicine and Surgery (DIMEC), Division of Obstetrics and Gynecology, University of Bologna, Via Massarenti 13, 40138 Bologna, Italy.
authors.forename: Gianluigi
authors.initials: G
authors.lastname: Pilu
mesh_terms: D000138:Acidosis / Q000503:physiopathology*; D000328:Adult; D015148:Cardiotocography / Q000145:classification*; D016022:Case-Control Studies; D005260:Female; D006340:Heart Rate, Fetal / Q000502:physiology*; D006801:Humans; D007748:Labor Stage, Second / Q000502:physiology*; D011247:Pregnancy; D012189:Retrospective Studies
keywords: Asphyxia; Cardiotocography; Fetal acidemia; Labor; Piquard; Second stage