The accuracy of measurements of intrauterine pressure during labor: a statistical analysis.

Abstract For nine patients undergoing labor, the intrauterine pressure of each contraction after rupture of the membranes was recorded by three separated catheters. The resultant data are statistically analyzed by a variety of methods. The main effects of contractions and catheters and the interaction between these effects are examined by the analysis of variance. Components of variance due to each of these three sources and due to random error are estimated. The standard deviation that would be expected had only one catheter been employed is then estimated to lie between 5 and 10 mm Hg. Differences in this last measure of variability are shown to be statistically significant among the nine patients. Finally, a graphical method is used to illustrate the variability of measurement as recorded by different catheters measuring the same contraction.