title: Misidentification of maternal heart rate as fetal on cardiotocography during the second stage of labor: the role of the fetal electrocardiograph.
abstract: OBJECTIVE
  To identify the incidence of fetal heart rate (FHR) accelerations in the second stage of labor and the role of fetal electrocardiograph (ECG) in avoiding misidentification of maternal heart rate (MHR) as FHR.
  
  
  METHODS
  Retrospective observational study.
  
  
  METHODS
  University hospital labor ward, London, UK.
  
  
  METHODS
  Cardiotocograph (CTG) tracings of 100 fetuses monitored using external transducers and internal scalp electrodes.
  
  
  METHODS
  CTG traces that fulfilled inclusion criteria were selected from an electronic FHR monitoring database.
  
  
  METHODS
  Rate of accelerations during external and internal monitoring as well as decelerations for a period of 60 minutes prior to delivery were determined. The role of fetal ECG in differentiating between MHR and FHR trace was explored.
  
  
  RESULTS
  Decelerations occurred in 89% of CTG traces during the second stage of labor. Accelerations indicating possible recording of FHR or MHR were found in 28.1 and 10.9% of cases recorded by an external ultrasound transducer as well as internal scalp electrode, respectively. Accelerations coinciding with uterine contractions occurred only in 11.7 and 4% of external and internal recording of FHR, respectively. Absence of 'p-wave' of the ECG waveform was associated with MHR trace.
  
  
  CONCLUSIONS
  Decelerations were the commonest CTG feature during the second stage of labor. The incidence of accelerations coinciding with uterine contractions was less than half in fetuses monitored using a fetal scalp electrode. Analysing the ECG waveform for the absence of 'p-wave' helps in differentiating MHR from FHR.
authors.affiliation: St. George's University of London, London, UK.
authors.forename: Raisha
authors.initials: R
authors.lastname: Nurani
authors.forename: Edwin
authors.initials: E
authors.lastname: Chandraharan
authors.forename: Virginia
authors.initials: V
authors.lastname: Lowe
authors.forename: Austin
authors.initials: A
authors.lastname: Ugwumadu
authors.forename: Sabaratnam
authors.initials: S
authors.lastname: Arulkumaran
mesh_terms: D000328:Adult; D015148:Cardiotocography; D004562:Electrocardiography / Q000295:instrumentation; D005260:Female; D005323:Fetal Monitoring / Q000379:methods*; D006339:Heart Rate / Q000502:physiology*; D006340:Heart Rate, Fetal / Q000502:physiology*; D006801:Humans; D007743:Labor, Obstetric; D011247:Pregnancy; D012189:Retrospective Studies