["Quantitative cardiotocography"--clinical practice guideline]

The "quantitative cardiotocography" method provides important information about the condition of the fetus during labor, non-invasively and in real time. Since the forecast pH-results are being updated every 5 (five) minutes, significant differences in the readings for pH can be observed. In certain cases this can hamper the evaluation of fetal condition and lead to contradictions. Such inconveniences can be easily avoided by using the arithmetic average value of the last 6 forecast results for pH, generated by the quantitative cardiotocography software. Another inconvenience of the "quantitative cardiotocography" method lies in the fact that the components involved in the formation of CTG-score seem to be unequal in terms of potential for evaluating the fetal condition. Based on that, we believe that clinical practice guideline is needed. We developed such guideline based on two main criteria: the arithmetic average value over the last 6 (six) pH estimates; which components of the CTG-score are involved in the formation of the pH forecast readings.

Our previous studies demonstrated that in 85% of all cases, the actual pH value of the newborn was in the range of -0037/+0046 from the average arithmetic value of the last six (6) pH estimates before the delivery. Based on this variability in the pH forecast results we defined three groups of findings--normal (pH 7.350 to 7.237), suspect (pH of 7.237 to 7.137) and abnormal (pH < 7.137). In another study, we differentiated several varieties of CTG-score (with very high, high, satisfactory and low predictive value), depending on the observed deviations between forecast and actual pH results.

pH forecast results should always be assessed together with the composition of the CTG-score. This can be achieved by using the presented clinical guideline, which also contains recommendations for adopting specific obstetric behavior, based on the "quantitative cardiotocography" readings.

In future studies we will investigate if it is possible the presented clinical practice guideline to replace fetal blood sampling for intrapartal assessment of the fetal condition. Further clinical studies will clarify whether the use of this clinical guideline could lead to a reduction in the incidence of metabolic acidosis in newborns or change the percentage of operative deliveries compared with the cases where classical indirect cardiotocography was used.