title: Monitoring uterine activity during labor: a comparison of 3 methods.
abstract: OBJECTIVE
  Tocodynamometry (Toco; strain gauge technology) provides contraction frequency and approximate duration of labor contractions but suffers frequent signal dropout, necessitating repositioning by a nurse, and may fail in obese patients. The alternative invasive intrauterine pressure catheter (IUPC) is more reliable and adds contraction pressure information but requires ruptured membranes and introduces small risks of infection and abruption. Electrohysterography (EHG) reports the electrical activity of the uterus through electrodes placed on the maternal abdomen. This study compared all 3 methods of contraction detection simultaneously in laboring women.
  
  
  METHODS
  Upon consent, laboring women were monitored simultaneously with Toco, EHG, and IUPC. Contraction curves were generated in real-time for the EHG, and all 3 curves were stored electronically. A contraction detection algorithm was used to compare frequency and timing between methods. Seventy-three subjects were enrolled in the study; 14 were excluded due to hardware failure of 1 or more of the devices (n = 12) or inadequate data collection duration (n = 2).
  
  
  RESULTS
  In comparison with the gold-standard IUPC, EHG performed significantly better than Toco with regard to the Contractions Consistency Index (CCI). The mean CCI for EHG was 0.88 ± 0.17 compared with 0.69 ± 0.27 for Toco (P < .0001). In contrast to Toco, EHG was not significantly affected by obesity.
  
  
  CONCLUSIONS
  Toco does not correlate well with the gold-standard IUPC and fails more frequently in obese patients. EHG provides a reliable noninvasive alternative, regardless of body habitus.
authors.affiliation: Department of Anesthesiology and Obstetrics and Gynecology, University of Florida College of Medicine, Gainesville, FL, USA. teuliano@ufl.edu
authors.forename: Tammy Y
authors.initials: TY
authors.lastname: Euliano
authors.forename: Minh Tam
authors.initials: MT
authors.lastname: Nguyen
authors.forename: Shalom
authors.initials: S
authors.lastname: Darmanjian
authors.forename: Susan P
authors.initials: SP
authors.lastname: McGorray
authors.forename: Neil
authors.initials: N
authors.lastname: Euliano
authors.forename: Allison
authors.initials: A
authors.lastname: Onkala
authors.forename: Anthony R
authors.initials: AR
authors.lastname: Gregg
mesh_terms: D000328:Adult; D004576:Electromyography / Q000379:methods*; D005260:Female; D005323:Fetal Monitoring / Q000379:methods*; D006801:Humans; D007743:Labor, Obstetric / Q000502:physiology*; D011247:Pregnancy; D014590:Uterine Contraction / Q000502:physiology*; D018590:Uterine Monitoring / Q000295:instrumentation / Q000379:methods*; D014599:Uterus / Q000502:physiology*