Intrapartum fetal oxygen saturation monitoring in congenital fetal heart block

Fetal heart block: Vaginal delivery an option

BACKGROUND

Fetal heart block (FHB) occurs in approximately 1:20 000 births and is associated with significant morbidity and mortality. Vaginal delivery with intrapartum fetal scalp lactate monitoring is offered as an option at our centre for selected cases, in contrast with the published literature advocating caesarean birth.

AIMS

To review perinatal outcomes at delivery for FHB at a tertiary referral hospital.

MATERIALS AND METHODS

Ours was a retrospective cohort study from 1 January, 2007 to 30 June, 2020. The infant outcomes are summarised in three delivery groups: vaginal delivery, planned caesarean section (CS) and unplanned CS.

RESULTS

There were 23 newborns in the study period, with a median gestation at birth of 37.2 weeks and there was one antepartum fetal death in this cohort. Vaginal delivery was planned in 12 women: eight had normal births, three of these women progressed to an intrapartum (unplanned) CS and one woman had a planned CS. All live babies in the vaginal delivery cohort had an Apgar score greater than seven at five minutes. Of the 22 newborns, six required intubation, of which five had been delivered by a planned CS.

CONCLUSION

Our data suggest that planned vaginal delivery is a safe option for selected women carrying a fetus with FHB. Managing labour with serial fetal scalp lactates, and the involvement of senior clinicians are important factors in achieving a successful outcome.

No. 197b-Fetal Health Surveillance: Intrapartum Consensus Guideline

OBJECTIVE

This guideline provides new recommendations pertaining to the application and documentation of fetal surveillance in the intrapartum period that will decrease the incidence of birth asphyxia while maintaining the lowest possible rate of obstetrical intervention. Pregnancies with and without risk factors for adverse perinatal outcomes are considered. This guideline presents an alternative classification system for antenatal fetal non-stress testing and intrapartum electronic fetal surveillance to what has been used previously. This guideline is intended for use by all health professionals who provide intrapartum care in Canada.

OPTIONS

Consideration has been given to all methods of fetal surveillance currently available in Canada.

OUTCOMES

Short- and long-term outcomes that may indicate the presence of birth asphyxia were considered. The associated rates of operative and other labour interventions were also considered.

EVIDENCE

A comprehensive review of randomized controlled trials published between January 1996 and March 2007 was undertaken, and MEDLINE and the Cochrane Database were used to search the literature for all new studies on fetal surveillance antepartum. The level of evidence has been determined using the criteria and classifications of the Canadian Task Force on Preventive Health Care (Table 1).

SPONSOR

This consensus guideline was jointly developed by the Society of Obstetricians and Gynaecologists of Canada and the British Columbia Perinatal Health Program (formerly the British Columbia Reproductive Care Program or BCRCP) and was partly supported by an unrestricted educational grant from the British Columbia Perinatal Health Program. RECOMMENDATION 1: LABOUR SUPPORT DURING ACTIVE LABOUR: RECOMMENDATION 2: PROFESSIONAL ONE-TO ONE CARE AND INTRAPARTUM FETAL SURVEILLANCE: RECOMMENDATION 3: INTERMITTENT AUSCULTATION IN LABOUR: RECOMMENDATION 4: ADMISSION FETAL HEART TEST: RECOMMENDATION 5: INTRAPARTUM FETAL SURVEILLANCE FOR WOMEN WITH RISK FACTORS FOR ADVERSE PERINATAL OUTCOME: When a normal tracing is identified, it may be appropriate to interrupt the electronic fetal monitoring tracing for up to 30 minutes to facilitate periods of ambulation, bathing, or position change, providing that (1) the maternal-fetal condition is stable and (2) if oxytocin is being administered, the infusion rate is not increased (III-B). RECOMMENDATION 6: DIGITAL FETAL SCALP STIMULATION: RECOMMENDATION 7: FETAL SCALP BLOOD SAMPLING: RECOMMENDATION 8: UMBILICAL CORD BLOOD GASES: RECOMMENDATION 9: FETAL PULSE OXIMETRY: RECOMMENDATION 10: ST WAVEFORM ANALYSIS: RECOMMENDATION 11: INTRAPARTUM FETAL SCALP LACTATE TESTING.

Intrapartum oximetry of the fetus

Fetal monitoring during labor aims to identify fetal problems which, if uncorrected, may result in morbidity or death. A nonreassuring or abnormal fetal heart rate trace by cardiotocography (CTG) does not necessarily equate with fetal hypoxia and/or acidosis. However, in the absence of more objective data, the use of CTG often results in variable, but inappropriately high, operative delivery rates (forceps, vacuum, or cesarean delivery) for nonreassuring fetal status in many hospitals. The addition of fetal pulse oximetry (FPO) has the potential to improve the assessment of fetal well-being during labor. In this review we consider several aspects of FPO. Several factors, such as sensor to skin contact, uterine contractions, fetal hair, and caput succedaneum, influence the performance and use of FPO. Issues such as clinicians' perspectives of FPO sensor placement, maternal perspectives of FPO during labor, and an economic analysis have all favored FPO. Several randomized controlled trials (RCTs) of FPO reported a reduction in cesarean delivery for nonreassuring fetal status when FPO was added to conventional CTG monitoring, with no difference in overall cesarean delivery rates. One large RCT reported no difference in mode of birth for any indication. Several issues relevant to the future of FPO have been addressed by these RCTs, the major issue being that it makes no difference to cesarean rates. It may be argued that FPO has a valid clinical use in monitoring the fetus with congenital heart block. Additionally, in situations of nonreassuring fetal status and dystocia, FPO may provide the necessary reassurance until adequate resources for cesarean delivery are available.

The effect of intrapartum fetal pulse oximetry, in the presence of a nonreassuring fetal heart rate pattern, on operative delivery rates: a multicenter, randomized, controlled trial (the FOREMOST trial)

OBJECTIVE

The objective of the study was to compare operative delivery rates for nonreassuring fetal status between 2 groups of laboring women: those having conventional cardiotocograph monitoring and those having cardiotocograph monitoring plus fetal pulse oximetry.

STUDY DESIGN

The intrapartum fetal oximetry prospective, multicenter, randomized, controlled trial (the FOREMOST trial) was conducted in 4 Australian maternity hospitals. The primary outcome was operative birth rates for nonreassuring fetal status.

RESULTS

There was a statistically significant 23% relative risk reduction in operative delivery for nonreassuring fetal status in the fetal pulse oximetry + cardiotocograph group (n = 75 of 305, 25%), compared with those in the cardiotocograph-only group (n = 95/295, 32%) (relative risk 0.77, 95% confidence interval 0.599, 0.999, P = .048). There were no significant between-group differences in overall operative births (fetal pulse oximetry + cardiotocograph group 73%, cardiotocograph-only group 71%, relative risk 1.04, 95% confidence interval 0.94, 1.15, P = .478) or neonatal outcomes.

CONCLUSION

The use of fetal pulse oximetry to augment fetal well-being assessment during labor resulted in a statistically significant reduction in the operative intervention for nonreassuring fetal status, compared with the use of conventional cardiotocograph monitoring alone. This reduction was achieved with no significant difference in neonatal outcomes.

Update on intrapartum fetal pulse oximetry

This article examines the current status of fetal pulse oximetry (FPO) as a means of intrapartum assessment of fetal wellbeing. FPO has been developed to a stage where it is a safe and accurate indicator of intrapartum fetal oxygenation. In general, sliding the FPO sensor along the examiner's fingers and through the cervix, to lie alongside the fetal cheek or temple is easy The recent publication of a randomised controlled trial (RCT) of FPO versus conventional intrapartum monitoring has validated its use to reduce caesarean section rates for nonreassuring fetal status. An Australian multicentre RCT is currently underway. Maternal satisfaction rates with FPO are high. FPO may be used during labour when the electronic fetal heart rate trace is nonreassuring or when conventional monitoring is unreliable, such as with fetal arrhythmias. If the fetal oxygen saturation (FSpO2) values are < 30%, prompt obstetric intervention is indicated, such as fetal scalp blood sampling or delivery FSpO2 monitoring should not form the sole basis of intrapartum fetal welfare assessment. Rather, the whole clinical picture should be considered.

Intrapartum fetal pulse oximetry. Part 2: Clinical application

Part II continues by discussing the clinical application of fetal pulse oximetry in intrapartum fetal surveillance as reviewed in the literature. It profiles the predictive ability of fetal pulse oximetry and its correlation with conventional methods of fetal monitoring. In addition, an account is made of its limitations, safety, and acceptability in clinical practice.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians

LEARNING OBJECTIVES

After completion of this article, the reader will be able to describe the predictive abilities of fetal pulse oximetry and its correlation with conventional methods of fetal monitoring, to define the critical threshold of fetal oxygen saturation, and to summarize the safety of fetal pulse oximetry.