375 The quality of intrapartum cardiotocography in preterm labor

Abstract

Although monitoring of the fetal heart rate with cardiotocography is now also applied to fetuses of lower gestational ages, the value and the quality of fetal heart rate monitoring in preterm fetuses is unclear. The aim of this study is to determine the quality of the fetal heart rate recording during preterm labor below 28 weeks gestational age and contribute to the discussion if cardiotocography is of value for the extreme preterm fetus. From January 2010 to December 2019, data of 95 fetal heart rate recordings of singleton fetuses between 24 to 28 weeks gestational age were collected at the Amsterdam University Medical Center, location VUmc. Fetal heart rate tracings had a duration of at least 30 minutes. Data were obtained via external ultrasound mode. The quality of the fetal heart rate recordings was determined by the median signal loss and by the proportion of cases exceeding the threshold of 20% signal loss, based on the guidelines of the International Federation of Gynaecology and Obstetrics (FIGO) for adequate quality. Signal loss was analyzed with a computer program. Data of all recordings were divided in two groups according to gestation to determine a relationship between signal loss and the following variables: gestational age, maternal overweight and mode of delivery. Non-parametric tests and chi-square tests were used to determine statistical significance. During the first stage of labor, approximately one-third of the recordings exceeded the 20% FIGO-criterion for adequate signal quality. In the second stage of labor, this was nearly 75%. Similarly, the median signal loss was 13% during the first and 30% during the second stage of labor (p<0.01). Gestational age, mode of delivery and maternal overweight were not associated with fetal signal loss. Almost one-third (31%) of first stage the fetal heart rate recordings during extreme preterm labor was of inadequate quality. During the second stage of labor quality was even worse with percentages up to 75%. Fetal heartrate monitoring in the extreme preterm fetus is therefore controversial and should be used with caution.View Large Image Figure ViewerDownload Hi-res image Download (PPT)