Using fetal scalp stimulation with Doppler ultrasonography to enhance intermittent auscultation in low-resource settings: a diagnostic trial from Tanzania

Fetal monitoring technologies for the detection of intrapartum hypoxia - challenges and opportunities

Intrapartum fetal hypoxia is related to long-term morbidity and mortality of the fetus and the mother. Fetal surveillance is extremely important to minimize the adverse outcomes arising from fetal hypoxia during labour. Several methods have been used in current clinical practice to monitor fetal well-being. For instance, biophysical technologies including cardiotocography, ST-analysis adjunct to cardiotocography, and Doppler ultrasound are used for intrapartum fetal monitoring. However, these technologies result in a high false-positive rate and increased obstetric interventions during labour. Alternatively, biochemical-based technologies including fetal scalp blood sampling and fetal pulse oximetry are used to identify metabolic acidosis and oxygen deprivation resulting from fetal hypoxia. These technologies neither improve clinical outcomes nor reduce unnecessary interventions during labour. Also, there is a need to link the physiological changes during fetal hypoxia to fetal monitoring technologies. The objective of this article is to assess the clinical background of fetal hypoxia and to review existing monitoring technologies for the detection and monitoring of fetal hypoxia. A comprehensive review has been made to predict fetal hypoxia using computational and machine-learning algorithms. The detection of more specific biomarkers or new sensing technologies is also reviewed which may help in the enhancement of the reliability of continuous fetal monitoring and may result in the accurate detection of intrapartum fetal hypoxia.

MANUAL FETAL STIMULATION DURING INTRAPARTUM FETAL SURVEILLANCE: A RANDOMISED CONTROLLED TRIAL: CharacteristicMaternal outcome

BACKGROUND

Manual fetal stimulation, either by mechanical manipulation or by stimulation of the fetal scalp is known to evoke a fetal heart response in a normal fetus.

OBJECTIVES

To assess the clinical effectiveness of manual fetal stimulation in assessment of fetal well-being during labor compared with no stimulation among women with a singleton pregnancy. To study the maternal and neonatal outcomes in the two groups.

STUDY DESIGN

A randomized controlled trial undertaken in the department of Obstetrics and Gynecology at a tertiary care teaching hospital between 2014 and 2016.

INCLUSION CRITERIA

Women with a singleton pregnancy at or after 37 weeks of gestation with cephalic presentation in labor having one of the following abnormalities on fetal heart tracing - fetal heart rate less than 110 beats per minute or more than 160 beats per minute, variable decelerations, late decelerations, minimal or absent beat to beat variability.

EXCLUSION CRITERIA

women requiring an immediate cesarean section; conditions which would preclude a vaginal delivery; intrauterine fetal demise or a major fetal congenital abnormality. The women were followed in labor and randomised to either the manual stimulation group or the no stimulation group when one of the CTG abnormalities were present. In the manual stimulation group the fetus was stimulated, abdominally by holding the head in the palm of one hand when the cervical dilatation was less than 3cm or vaginally by pinching the scalp of the fetus when the cervical dilatation was ≥3cm. After delivery, cord blood sample was collected and pH estimated. Mother and baby were followed up until discharge and mode of delivery, cord blood pH at birth, Apgar score at 1 and 5 minutes, neonatal intensive care unit admissions and duration of stay were the outcomes studied. Data was entered and compiled as frequency and percent for categorical variables. For continuous variables, data was calculated using mean and standard deviation. Chi-square test was used for assessing the association between the intervention and fetal and maternal outcomes.

RESULTS

A total of 327 women were included in the trial, of whom 164 were in the manual fetal stimulation group (group 1) and 163 were in the 'no stimulation' group (group 2). The Cesarean section rates were 25.61% in group 1 and 30.67% in group 2 (p=0.308). The mean cord blood pH at birth was 7.267±0.027 in group 1 and 7.265±0.024 in group 2 (p=0.479)and Apgar score at 1 min and 5 min (p=0.169 and p=0.423 respectively between the two groups) were not found to be statistically different among the two groups.

CONCLUSION

There is no significant change in feto-maternal outcomes with manual fetal stimulation in women having non-reassuring cardiotocographic changes in labor.

How to reduce fetal scalp blood sampling? A retrospective study evaluating the diagnostic value of scalp stimulation to predict fetal wellbeing assessed by scalp blood sampling

BACKGROUND

The Fetal Blood Sample (FBS) is used as an indicator of fetal acidosis during labor. Its place is discussed through the lack of randomized trials, as well as the limitations related to the technical procedure. An alternative could be the Fetal Scalp Stimulation (FSS).

AIM

Our objective was to describe the FSS diagnostic value to predict fetal wellbeing defined from FBS.

METHODS

The FSS consisted in a digital scalp stimulation for 15 s. Test was negative when an acceleration and/or a normal variability were elicited in the 2 min following. FSS was performed before each FBS which was classified as normal when pH was > 7.25. The diagnostic value was assessed by sensibility, specificity, positive and negative predictive values.

FINDINGS

148 women were included in our center from February to December 2019. Of the 191 FBS procedures, when accelerations were elicited sensibility was 58,3 (36.8-77.1), specificity was 67,5 (59.3-75), positive predictive value was 20,9 (12.5-32.9) and negative predictive value was 91.7 % (95 %CI, 85-95.5).

DISCUSSION

FBS is considered as the gold standard in our study which could be discussed as it is abandoned in some countries because of its questioned reliability and the lack of controlled randomized trials.

CONCLUSION

This study suggests that FSS could be an interesting alternative adjunctive test to perform in the first instance as it seems to be reliable, non-invasive and easy to perform in order to limit FBS only to absence of acceleration after FSS.

Effectiveness of fetal scalp stimulation test in assessing fetal wellbeing during labor, a retrospective cohort study

BACKGROUND

It is discussed whether fetal scalp stimulation (FSS) test is a reliable complimentary tool to cardiotocography (CTG) to assess fetal wellbeing during labor. The test is based on the assumption that a well-oxygenated fetus, in contrast to the depressed fetus, will respond to a certain stimulus. The aim of this study was to investigate the effectiveness of the FSS-test.

METHODS

A retrospective observational study carried out Copenhagen University Hospital, Herlev, Denmark. Laboring women with singleton pregnancies in cephalic presentation after gestation week 33 and indication for fetal blood sampling (FBS) were eligible for inclusion. The FSS-test was classified as positive when an acceleration was absent at the time of FBS and negative when an acceleration was present. Lactate in scalp blood was measured by the point-of-care device LactatePro™ and pH in artery umbilical cord blood by the stationary blood gas analyzer ABL800. Lactate level < 4.2 mmol/L in scalp blood and arterial cord pH > 7.1 were cut-offs for normality.

RESULTS

Three hundred eighty-five women were included. The cohort was divided by the FBS-to-delivery time: Group 1 (n = 128) ≤ 20 min, Group 2 (n = 117) 21-59 min and Group 3 (n = 140) ≥ 60 min. The proportion of FSS-positive tests differed significantly between the groups (p < 0.000). In Group 1 the sensitivity, specificity and likelihoods for scalp lactate ≥4.2 mmol/L were 81.5 (95% CI 67-90.1), 13.3 18.5 (95% CI 5.9-24.6), LHR+ 0.94 (95% CI 0.8-1.1) and LHR - 1.4 (95% CI 0.6-3.2) and for umbilical artery pH ≤ 7.10 the values were 82.6% (95% CI 61.2-95.1), 16% (95% CI 9.4-24.7), 1.0 (95% CI 0.8-1.2) and 1.1 (95% CI 0.4-3) respectively. Regardless of the FBS-to-delivery time the LHR+ for lactate ≥4.2 mmol/L increased to 1.38 (95% CI 1.2-1.6).

CONCLUSION

The effectiveness of scalp stimulation test was poor for both ruling in and out fetal hypoxia during labor. Absence of a provoked acceleration seems to be a normal phenomenon in the second stage of labor.