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Intrapartum monitoring of high-risk deliveries with ST analysis of the fetal electrocardiogram: an observational study of 6010 deliveries

Authors

  • JÖRG KESSLER,

    Corresponding author
    1. Department of Clinical Medicine, Clinical Fetal Physiology Research Group, Haukeland University Hospital, Bergen, Norway
    • Department of Obstetrics and Gynecology, Haukeland University Hospital, Bergen, Norway
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  • DAG MOSTER,

    1. Department of Clinical Medicine, Haukeland University Hospital, Bergen, Norway
    2. Department of Pediatrics, Haukeland University Hospital, Bergen, Norway
    3. Public Health and Primary Health Care, University of Bergen, Bergen, Norway
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  • SUSANNE ALBRECHTSEN

    1. Department of Obstetrics and Gynecology, Haukeland University Hospital, Bergen, Norway
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  • J.K. has received a lecture fee from Neoventa Medical, Mölndal, Sweden on one occasion. S.A. and D.M. have stated explicitly that there are no conflicts of interest in connection with this article.

Correspondence

Jörg Kessler, MD, PhD, Department of Clinical Medicine, Division of Obstetrics and Gynecology, Haukeland University Hospital, N-5021 Bergen, Norway. E-mail: jorg.kessler@kk.uib.no

Abstract

Objective

To evaluate the clinical use of ST analysis (STAN) for intrapartum monitoring of high-risk pregnancies.

Design

Prospective observational study.

Setting

University hospital, Norway, 2004–2008.

Population

Singleton pregnancies with a gestational age above 35+6 weeks.

Methods

Analysis of maternal and neonatal outcomes for all deliveries according to the method of intrapartum monitoring.

Main outcome measures

Prevalence of cord metabolic acidosis (pH < 7.05, extracellular fluid base deficit (extracellular fluid) >12 mmol/L).

Results

Of 23 203 deliveries, 6010 (25.9%) were monitored with STAN. Fetal blood sampling was performed in 146 (2.4%) of the 6010 cases. During the study period, the prevalence of cord metabolic acidosis and moderate cord acidosis (pH < 7.15) decreased in STAN-monitored deliveries from 1.4 to 0.3% (p = 0.01) and from 16.4 to 11.7% (p = 0.001), respectively. The prevalence of moderate and severe neonatal encephalopathy was 0.38%. In the birth population, the proportion of cesarean deliveries decreased from 10.1 to 8.8%. The risk of emergency cesarean section after STAN monitoring compared with those monitored with auscultation/cardiotocography was high (odds ratio 5.4, 95% confidence interval = 4.9–6.1) but remained stable during the study period.

Conclusions

ST analysis is a useful tool for identification of fetuses at risk of intrapartum hypoxia. Despite the restricted use of fetal blood sampling, we found a low proportion of cord metabolic acidosis and newborn morbidity.

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