title: Variation of safety indices during in the learning curve for color Doppler assessment of the fetal heart at 11+0 to 13+6 weeks' gestation.
abstract: OBJECTIVE
  The aim of our study was to analyze the variation of acoustic output, as expressed by the thermal (TI) and mechanical index (MI), during the learning curve for a fetal heart scan at 11-13 gestational weeks, with the introduction of a new ultrasound system.
  
  
  METHODS
  This was a prospective, observational study on 303 normal fetuses. The fetal heart was examined transabdominally using B-Mode and high definition (HD) color Doppler to obtain standard parameters: four-chamber, outflow tracts and three-vessel-trachea views. Data were analyzed in groups of 20 consecutive examinations and the percentage of successful examinations was calculated. TI and MI were retrieved from HD color Doppler examinations of the fetal heart and from pulsed-wave Doppler assessment of the tricuspid flow and ductus venosus.
  
  
  RESULTS
  MI values from the color Doppler examination of the fetal heart showed a continuous decrease (0.81 to 0.75, p<0.001), along the learning phase. TI and MI indices from pulsed-wave Doppler evaluation of the tricuspid flow increased at the beginning of the learning phase and stabilized afterwards (0.34 to 0.36, p<0.05 and 0.37 to 0.4, p<0.001, respectively). TI from color Doppler exam of the heart and indices from ductus venosus assessment were very constant and did not change along the studied periods. The length of Doppler examination of the heart increased after about 80 cases by 25%, to a mean of 4 minutes (p<0.05).
  
  
  CONCLUSIONS
  Safety indices from Doppler evaluation of the fetal heart and tricuspid flow vary during the learning curve for fetal heart assessment. Also, the occurrence of constant values suggests the potential for their supplementary active reduction. For a better adaptation to a new ultrasound technology, the sonographer should scan the fetal heart longer in the first trimester and follow displayed safety indices along the first 80 cases.
authors.affiliation: Department of Obstetrics and Gynecology, University of Medicine and Pharmacy "Gr. T. Popa" Iasi, Romania. dragos.nemescu@umfiasi.ro.
authors.forename: Dragos
authors.initials: D
authors.lastname: Nemescu
authors.affiliation: Department of Obstetrics and Gynecology, University of Medicine and Pharmacy "Gr. T. Popa" Iasi, Romania.
authors.forename: Anca
authors.initials: A
authors.lastname: Berescu
authors.affiliation: Deptartment of Biomedical Sciences, University of Medicine and Pharmacy "Gr. T. Popa" Iasi, Romania.
authors.forename: Cristian
authors.initials: C
authors.lastname: Rotariu
mesh_terms: D018618:Echocardiography, Doppler, Color / Q000706:statistics & numerical data*; D005260:Female; D005318:Fetal Heart / Q000000981:diagnostic imaging*; D005865:Gestational Age; D006801:Humans; D059032:Learning Curve; D008297:Male; D061214:Patient Safety / Q000706:statistics & numerical data*; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011446:Prospective Studies; D000069079:Radiation Exposure / Q000706:statistics & numerical data*; D012383:Romania / Q000453:epidemiology; D013016:Sound; D016216:Ultrasonography, Prenatal / Q000706:statistics & numerical data*; D016526:Workload / Q000706:statistics & numerical data