Examining laboratory accuracy and precision of the new Iranian device “Cervical Dilatometer” in measuring cervix dilatation

Authors: Z.Taghizadeh, A. Kazemnejad-Lili, F. Hajati

Abstract

The objective of the study was to assess laboratory accuracy and precision of the newly invented cervimetry device “cervical dilatometer” in measuring cervix dilatation that is an important part of monitoring labor progress as an essential aspect of maternity care which may help health providers predict potential problems and perform proper interventions when needed. 7 midwives as examiners in two groups of experimental phases were asked to measure cervix dilatation in artificial simulators ranging from 40 to 100 mm by means of the device blindly. Results were recorded and then using a simple calculation (according to Thales’ triangle rule) by one of the researchers and dilatations were reported.  For accuracy and precision of the instrument ICC (Inter-class Correlation) between simulators and examiners reports, ICC between observers, Pearson’s Correlation and Standard Error, all with 95% confidence interval, were used. 95 examinations (35 in Phase 1 and 60 in Phase 2) in 37 simulators (7 in phase 1 and 30 in phase 2) were performed, none of the cases excluded. According to the statistical analyses there were positive correlations between the instrument reports and simulators real sizes in either phases (ICC=0.968 in phase 1  and 0.834 in phase 2), Reliability of the instrument using Cronbach’s Alpha was 0.995, inter-observer agreement due to ICC and Pearson’s correlation was 0.995 and 0.697 in phase 1 and phase 2 respectively. Cervical Dilatometer meets accuracy, precision and reliability requirements to be used as a cervimetry instrument in laboratory phase. Further research is needed to determine those elements in clinical set-up.

Keywords: Accuracy, Precision, Cervical dilatation, Device