The First World Congress On: Controversies in Obstetrics, Gynecology & Infertility
Prague, Czech Republic - 1999

Is There a Place for Electronic Fetal Monitoring in Low Risk Pregnancy
A. Sinha and S. ARULKUMARAN 
Academic Unit, Derby City General Hospital, Derby, United Kingdom 

Available for download in Word Document format

Minimizing fetal morbidity during labor is one of the principal aims of intrapartum care. Electronic fetal heart rate monitoring (EFM)and intermittent auscultation are the known modalities of intrapartum fetal surveillance. EFM during labour was introduced with the aim of preventing perinatal mortality and the occurrence of hypoxic damage to the fetus. It became popular and almost universal in its application, particularly in the developed world even before it was fully evaluated. More than two decades later and following numerous randomised clinical trials, the benefit of EFM over intermittent auscultation remains uncertain.

The largest randomised trial of EFM carried out in Dublin involved 13,000 women. There was no significant difference in the incidence of intrapartum still birth or neonatal death1. Leveno et al2 studied 34,995 women comparing universal EFM with selective fetal monitoring and observed similar results. There have been 12 randomised trials so far, the results of these show that in low risk pregnancies, EFM offers no added benefit over intermittent auscultation. Meta-analysis 3 of published randomised controlled trials (RCT’s) comparing the efficacy and safety of EFM with intermittent auscultation revealed an increase in maternal morbidity due to a higher incidence of caesarean sections (CS) and operative vaginal delivery. The risk of a CS delivery was the greatest in low risk pregnancies. The only significant clinical benefit with routine use of EFM was the reduction in the incidence of neonatal seizures. Vintzileous4 reported that the detection of fetal acidemia (pH<7.15) was better with EFM in comparison to intermittent auscultation(97% vs37%) However on closer scrutiny it was found that in the EFM group there was a greater frequency of acidemia(9.9% vs. 4.9%) and the acidemia was more severe.Hence it would appear that EFM neither prevented nor did it reduce the severity of fetal acidemia. 

Inspite of an abundance of data arguing against the routine use of EFM it is still widely practiced in all centers. It is often used as a “babysitter” and as such it is much less expensive, if one to one care is not available for patients at low risk. The majority of infant brain damage occurs before the intrapartum period and in the absence of an acute intrapartum event only a small minority of fetus can potentially suffer from intrapartum hypoxia. Much of our monitoring is centered around these babies. Fetal heart rate abnormalities are quite common in labour. There are studies to show that even ‘experts’ vary greatly in their interpretation of different traces 5.Even if most of these changes are innocuous, it still generates great anxiety in both the patient and the medical team. Hence instead of a ritualistic use of EFM in every laboring woman, a more rational approach to fetal monitoring should be made. 

The Admission test may help to identify those cases at risk in labour at the same time doing away with continuous monitoring . This involves performing a period of continuous EFM on admission in early labour. The rationale behind it is that it can assess the ability of the fetus to withstand the functional stress of uterine contractions during early labour.If the cardiotocogram (CTG) is reactive, the risk of fetal hypoxia other than due to an acute event is low in the next few hours of labour6 . In the absence of acute events during labour, the admission test is a good screening test for predicting fetal well being and for classifying labour as a low risk one. If the admission test is reactive, a gradually developing hypoxia can be suspected by a rising fetal heart rate on auscultation7. Fetal acidemia is a slowly developing event from the onset of changes in the fetal heart rate. The fetus suffers from brain damage only when exposed to prolonged and profound hypoxia. In a gradually developing hypoxia, abnormal patterns may be present for 120 to 140 minutes before fetal acidemia increases significantly8.

EFM is easy to apply and gives a reliable recording of fetal heart rate, however this does not translate into a better outcome. Its routine use is seen more often in busy labour units where one to one care is not available. Defensive practice in Obstetrics is common place and is one of the reasons for the routine use of EFM even in low risk pregnancies. The number of cases studied to date in randomised controlled trials are inadequate to draw conclusions as to whether EFM is beneficial in low risk labour.

References

1. MACDONALD D, GRANT A, SHERIDAN-PEREIRA M, et al. The Dublin randomizes controlled trial intrapartum fetal heart rate monitoring. Am J Obstet Gynecol 52:524-39, 1985.

2. LEVENO KJ, CUNNINGHAM FG, NELSON S, et al. A prospective comparison of selective and universal electronic fetal monitoring in 34,995 pregnancies. N Eng J Med 315: 615-19 ,1986.
3. THAKER SB, STROUP DF, PETERSON HB. Efficacy and safety of intrapartum electronic fetal monitoring: an update. Obstet Gynecol 86:613-20 ,1995

4. VINTZILEOUS AM, NOCHIMSON DJ, ANTSAKLIS A, et al. Comparison of intrapartum electronic fetal heart rate monitoring versus intermittent auscultation in detecting fetal acidemia at birth. Am J Obstet Gynecol 173:1021-4 ,1995.

5. BEAULIEU MD, FABIA J, LEDUC B, et al. The reproducibility of intrapartum cardiotochogram assessments. Can Med J 127:214-6 ,1982.

6. INGEMARSSON I, ARULKUMARAN S, INGEMARSSON E, et al. Admission test: a screening test for fetal distress. Obstet General 68:800-6, 1986.

7. GIBB DMF & ARULKUMARAN S.Fetal monitoring in practice. Oxford: Butterworth Heinemann Ltd. 1992.

8. FLEISHER A,SCHULMAN H, JAGANI N, et al. The development of fetal acidosis in the presence of an abnormal fetal heart rate tracing, I. The average for gestational age fetus. Am J Obstet Gynecol 144:55- ,1982.