Outcome of severe intrapartum acidemia diagnosed with fetal scalp blood sampling

Long-term neurodevelopmental effects of exclusively high cord lactate levels in term newborn

INTRODUCTION

Cord arterial blood gas analysis (ABGA) results are used as diagnostic criteria for hypoxic-ischemic encephalopathy in newborns with suspected perinatal asphyxia. This study evaluated the effect of cord ABGA lactate level on the long-term neurodevelopment of newborns without any clinical signs of perinatal asphyxia.

METHODS

This clinical observation study was designed among term babies born between 2018 and 2019 in our unit. Cases with a 5-min Apgar score <7 and signs of fetal distress in their antenatal follow-up were excluded. The cases (n = 1438) were divided into two groups those with high cord lactate levels (above 5 mmol/L, n = 92) and those with low lactate levels (below 2 mmol/L, n = 255). An Ages and Stages Questionnaire, Third Edition (ASQ-3) developmental screening questionnaire was sent to all parents. Patients with a chronological age between 24 and 42 months and for whom the parents fulfilled the questionnaire (low lactate group, n = 29, and high lactate group, n = 45) were evaluated.

RESULTS

No difference was observed between the two groups in terms of demographic characteristics such as age (p = .1669), male gender (p = .906), mother's working situation (p = .948), mother's education level (p = .828), father's education level (p = .507), and family's total income (p = .642). Mean ACQ-3 developmental screening test scores were significantly lower in the high lactate group compared to the low lactate group concerning; fine motor (40 vs. 60, p = .001), problem-solving (50 vs. 60, p = .002), and personal social development (45 vs. 60, p = .003). No difference was observed in terms of communication and gross motor total scores.

DISCUSSION

In general practice, routine cord ABGA is not generally recommended for patients with normal Apgar scores and no suspected hypoxia. However, in this study, we observed that cases with a normal 5-min Apgar score, no suspected perinatal asphyxia, and a cord lactate value of ≥5 fell behind their peers when evaluated with the ACQ-3 developmental screening questionnaire.

The association of intrapartum deceleration and acceleration areas with MRI findings in neonatal encephalopathy

BACKGROUND

Hypoxic-ischemic encephalopathy (HIE) is an important contributor to disability worldwide. The current cardiotocography (CTG) predictive value for neonatal outcome is limited.

OBJECTIVE

To assess the association of intrapartum CTG deceleration and acceleration areas with early MRI cerebral pathology in infants with HIE.

METHODS

Term and near-term low-risk pregnancies that resulted in HIE, treated with therapeutic hypothermia with sufficient CTG records from a single, tertiary hospital between 2013 and 2021 were enrolled. Accelerations and decelerations areas, their minimum and maximum depths, and duration were calculated as well as the acceleration-to-deceleration area ratio during the 120 min prior to delivery. These data were assessed for associations with higher degrees of abnormality on early MRI scans.

RESULTS

A total of 77 infants were included in the final analysis. Significant associations between increased total acceleration area (p = 0.007) and between a higher acceleration-to-deceleration area ratio (p = 0.003) and better MRI results were detected.

CONCLUSION

In neonates treated for HIE, acceleration area and acceleration-to-deceleration ratio are associated with the risk of neonatal brain MRI abnormalities. To increase the role of these measurements as a relevant clinical tool, larger, more powered prospective trials are needed, using computerized real-time analysis.

IMPACT

The current cardiotocography predictive value for neonatal outcome is limited. This study aimed to assess the association of intrapartum deceleration and acceleration areas with the degree of cerebral injury in early cerebral MRI of neonates with encephalopathy. Lower acceleration area and acceleration-to-deceleration ratio were found to be associated with a higher degree of neonatal brain injury. Brain MRI is a marker of long-term outcome; its association with cardiotocography indices supports their association with long-term outcome in these neonates. Future computer-based CTG area analysis could assist in delivery room decision making to better time interventions and prevent hypoxic-ischemic encephalopathy.

Fetal lactate levels align with the stage of labour

AIM

To evaluate the association between lactate concentrations in fetal blood samples and the different advanced labour stages.

METHODS

Eighteen-month prospective population-based clinical study of 187 singleton pregnant women in labour who were monitored by fetal blood sampling (FBS) because of non-reassuring intrapartum CTG results at Kuopio University Hospital, Finland. Peripheral lactate concentration and pH were analysed at different stages of labour and in umbilical arterial samples immediately after delivery.

RESULTS

FBS samples (N = 350) were obtained from 5.4 % of all women in labour during the study period, and 48 % had spontaneous delivery, 27 % had vacuum-assisted vaginal delivery, and 25 % had nonelective Caesarean delivery. FBS lactate levels increased 4-11% with every 1-2 cm of cervical dilation and 18 % from early labour to fully dilated cervix. In 42 women with at least two FBSs, lactate levels increased significantly from the early I stage of labour and up to a fully dilated cervix. Lactate values were significantly higher in umbilical arterial samples compared to FBSs. Sensitivity of the highest FBS lactate values for the detection of birth asphyxia were considerably low varying between 42.9-57.1%.

CONCLUSION

FBS lactate levels were related to the stage of labour during vaginal delivery attempt. Wide range of lactate levels during labour complicates its use as a predictor of birth asphyxia.

Fetal heart rate short term variation during labor in relation to scalp blood lactate concentration

INTRODUCTION

Fetal heart rate short term variation (STV) decreases with severe chronic hypoxia in the antenatal period. However, only limited research has been done on STV during labor. We have tested a novel algorithm for a valid baseline estimation and calculated STV. To explore the value of STV during labor, we compared STV with fetal scalp blood (FBS) lactate concentration, an early marker in the hypoxic process.

MATERIAL AND METHODS

Software was developed which estimates baseline frequency using a novel algorithm and thereby calculates STV according to Dawes and Redman in up to four 30-minute blocks prior to each FBS. Cardiotocography traces from 1070 women in labor who had had FBS performed on 2134 occasions were analyzed.

RESULTS

In acidemic cases (lactate >4.8 mmol/L; Lactate Pro™), median STV 30 minutes prior to FBS was 7.10 milliseconds compared with 6.09 milliseconds in the preacidemic (4.2-4.8 mmol/L) and 5.23 milliseconds in the normal (<4.2 mmol/L) groups (P < .05). There was a positive correlation between lactate and STV (rho = 0.16-0.24; P < .05). Median lactate concentration in cases with STV <3.0 milliseconds (n = 160) was 2.3 mmol/L. When 2 FBS were performed within 60 minutes the change rate of lactate correlated to STV (rho = 0.33; P < .001). Cases with increasing lactate concentration had a median STV of 5.29 milliseconds vs 4.41 milliseconds in those with decreasing lactate (P < .001).

CONCLUSIONS

In the early stages of intrapartum hypoxia, STV increases, contrary to findings regarding chronic hypoxia in the antenatal period. The increase in the adrenergic surge is a likely explanation.

Infant outcome at four years of age after intrapartum sampling of scalp blood lactate for fetal assessment. A cohort study

OBJECTIVE

To correlate the value of lactate in fetal scalp blood at delivery and the outcomes of the offspring at four years of age.

METHODS

Cases where scalp blood lactate was taken within sixty minutes before delivery were identified from the randomized trial "Determination of pH or lactate in fetal scalp blood in management of intrapartum fetal distress". Data were grouped according to the generally accepted cutoffs for normality, pre-acidemia, acidemia and concentrations above mean +2 SD during the second stage. The outcome measures included gross-/fine motor function, vision, hearing, speaking and cognitive disorders, signs of central motor damage and referral to specialized pediatric services.

RESULTS

307 cases were available for final analyse. With normal scalp lactate concentration, the number of children with a diagnosed disorder was lower compared to the pre-acidemic/acidemic groups, although the findings were only significant for fine motor dysfunction (p = 0.036). Elevated lactate values were significantly associated with increased risk for a poorer capacity of attention and understanding of instructions (OR 1.37, 95% CI 1.07-1.74), and for fine motor dysfunction (OR 1.22, 95% CI 1.00-1.49) at the age of four.

CONCLUSION

Higher levels of lactate in fetal scalp blood seems to be associated with increased risk of an aberrant developmental outcome at four years of age in some areas.

Risk factors for intrapartum acidemia - a cohort study

PURPOSE

Birth acidemia is associated with short- and long-term morbidity in the child. Optimal intrapartum surveillance and timely interventions may reduce the incidence of these outcomes. Knowledge about conditions which increase the risks might be beneficial for optimal care. The aim with this study was to identify factors which increased the risk for lactacidemia in fetal scalp blood.

MATERIALS AND METHODS

A secondary analysis of a cohort study performed at Karolinska University Hospital Stockholm Sweden between February 2009 and February 2011. The study population included 1070 women in labor where fetal scalp blood sampling (FBS) was performed.

RESULTS

In a univariate logistic regression analysis for lactate >4.8 mmol/L at FBS, minor language barriers (OR 2.54; 95%CI 1.26-5.11), active bearing down (OR 2.46; 95%CI 1.12-5.39) and maternal height <155 cm (OR 2.15; 95%CI 1.08-4.26) were found as risk factors. In a multivariate logistic regression analysis, minor language barriers (OR 2.21; 95%CI 1.05-4.67) and active pushing (OR 2.68; 95%CI 1.20-6.00) remained significant.

CONCLUSIONS

Language barriers, active pushing and short stature were found to be significant risk factors for intrapartum lactacidemia. In the group with minor language problems better use of interpreters might be beneficial.

Lactate versus pH levels in fetal scalp blood during labor--using the Lactate Scout System

OBJECTIVE

To assess if lactate measured with the Scout Lactate System is a reliable alternative to pH in intrapartum monitoring of the fetus.

METHODS

A prospective study analyzing (1) the correlation between scalp lactate measured by the Scout Lactate System and the Automatic Blood Laboratory (ABL), (2) the correlation between lactate and pH measured in scalp blood and (3) the correlation between fetal scalp lactate and umbilical cord SBE. The sensitivity/specificity and positive/negative predictive values of lactate in predicting low pH were analyzed and expressed as Receiver Operating Curves (ROC).

RESULTS

Lactate measured by the Scout Lactate System and the ABL correlated well (r(2)=0.85). Both lactate and pH were measured in 1009 scalp blood samples. The sensitivity and specificity of lactate ≥ 4.8 mmol/l in predicting a pH <7.20 were 0.63 and 0.85, respectively. The correlation between scalp lactate measured within 15 min prior to delivery and the umbilical cord SBE was low.

CONCLUSION

Monitoring non-reassuring deliveries with scalp lactate instead of pH would have resulted in more (155 instead of 56) instrumental deliveries with no decrease in newborns with severe metabolic acidosis.

Intrapartum fetal scalp lactate sampling for fetal assessment in the presence of a non-reassuring fetal heart rate trace

BACKGROUND

Fetal scalp blood sampling for lactate estimation may be considered following identification of an abnormal or non-reassuring fetal heart rate pattern. The smaller volume of blood required for this test, compared with the more traditional pH estimation, may improve sampling rates. The appropriate use of this practice mandates systematic review of its safety and clinical effectiveness prior to widespread introduction.

OBJECTIVES

To evaluate the effectiveness and risks of fetal scalp lactate sampling in the assessment of fetal well-being during labour, compared with no testing or alternative testing.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 January 2015).

SELECTION CRITERIA

All published and unpublished randomised and quasi-randomised trials that compared fetal scalp lactate testing with no testing or alternative testing to evaluate fetal status in the presence of a non-reassuring cardiotocograph during labour.

DATA COLLECTION AND ANALYSIS

We used the standard methodological procedures of the Cochrane Pregnancy and Childbirth Group. Two review authors independently assessed the studies.

MAIN RESULTS

The search identified two completed randomised controlled trials (RCTs) and two ongoing trials. The two published RCTs considered outcomes for 3348 mother-baby pairs allocated to either lactate or pH estimation of fetal blood samples when clinically indicated in labour. Overall, the published RCTs were of low or unclear risk of bias. There was a high risk of performance bias, because it would not have been feasible to blind clinicians or participants.No statistically significant between-group differences were found for neonatal encephalopathy (risk ratio (RR) 1.00, 95% confidence interval (CI) 0.32 to 3.09, one study, 2992 infants) or death. No studies reported neonatal seizures. We had planned to report death with other morbidities, for example, neonatal encephalopathy; however, the data were not available in a format suitable for this, therefore death due to congenital abnormality was considered alone. The three reported neonatal deaths occurred in babies with diaphragmatic hernias (n = 2) or congenital cardiac fibrosis (n = 1). All three babies had been randomised to the pH group and were not acidaemic at birth.There were no statistically significant differences for any of the pre-specified secondary fetal/neonatal/infant outcomes for which data were available. This included low Apgar score at five minutes (RR 1.13, 95% CI 0.76 to 1.68, two studies, 3319 infants) and admission to neonatal intensive care units (RR 1.02, 95% CI 0.83 to 1.25, one study, 2992 infants), or metabolic acidaemia (RR 0.91, 95% CI 0.60 to 1.36, one study, 2675 infants) considered within the studies, either overall or where data were available for those where fetal blood sampling had occurred within 60 minutes of delivery.Similar proportions of fetuses underwent additional tests to further evaluate well-being during labour, including scalp pH if in the lactate group or scalp lactate if in the pH group (RR 0.22, 95% CI 0.04 to 1.30, two studies, 3333 infants;Tau² 1.00, I² = 58%). Fetal blood sampling attempts for lactate and pH estimation were successful in 98.7% and 79.4% of procedures respectively in the one study that reported this outcome.There were no significant between-group differences in mode of birth or operative birth for non-reassuring fetal status, either for all women, or within the group where the fetal blood sample had been taken within 60 minutes of delivery (for example, caesarean section for all enrolled, RR 1.09, 95% CI 0.97 to 1.22, two studies, 3319 women; operative delivery for non-reassuring fetal status for all enrolled RR 1.02, 95% CI 0.93 to 1.11, one study, 2992 women).Neither study reported on adverse effects of fetal scalp lacerations or maternal anxiety.

AUTHORS' CONCLUSIONS

When further testing to assess fetal well-being in labour is indicated, fetal scalp blood lactate estimation is more likely to be successfully undertaken than pH estimation. Further studies may consider subgroup analysis by gestational age, the stage of labour and sampling within a prolonged second stage of labour. Additionally, we await the findings from the ongoing studies that compare allocation to no fetal blood sample with sampling for lactate and address longer-term neonatal outcomes, maternal satisfaction with intrapartum fetal monitoring and an economic analysis.

Comparing fetal scalp lactate and umbilical cord arterial blood gas values

BACKGROUND

Fetal scalp lactate has been shown to be as effective as scalp pH in predicting fetal outcomes. However, there is limited clinical evidence to demonstrate a strong correlation with fetal acidaemia at birth.

AIMS

To compare the diagnostic accuracy of fetal scalp lactate and umbilical cord arterial blood gas values sampling, as it is used in clinical practice.

METHODS

A retrospective cohort study was performed on 661 term (≥37 weeks) births where a fetal scalp lactate sample was taken during labour. Cases were excluded where either the lactate was taken greater than 1 h prior to delivery, incomplete cord gas analyses were available, or a sentinel hypoxic event occurred prior to delivery. The final data set included 229 microvolume scalp lactate measurements which were compared with neonatal paired cord blood gas values taken at delivery.

RESULTS

A fetal scalp lactate measurement of ≥4.8 mmol/L had a positive predictive value (PPV) of 1% and a negative predictive value (NPV) of 100% in predicting umbilical artery pH ≤7.00, and a PPV of 5% and a NPV of 98% in predicting umbilical artery pH ≤7.10. The sensitivity and specificity for these values were 100%, 23% and 90%, 23%, respectively.

CONCLUSIONS

Fetal scalp lactate microsampling has a strong negative predictive value for fetal acidaemia at birth.

Lactate production as a response to intrapartum hypoxia in the growth-restricted fetus

OBJECTIVE

To analyse whether the increase in lactate in response to intrapartum hypoxia differs between small- (SGA), appropriate- (AGA) and large-for-gestational-age (LGA) fetuses.

DESIGN

Observational cohort study.

SETTING

Ten obstetric units in Sweden.

POPULATION

A cohort of 1496 women.

METHODS

A secondary analysis of a randomised controlled trial, in which 1496 women with fetal heart rate abnormalities, indicating fetal scalp blood sampling, were randomised to lactate analyses. After delivery, the neonates were divided according to birthweight for gestational age into SGA, AGA and LGA groups.

MAIN OUTCOME MEASURE

Lactate concentration in fetal scalp blood.

SECONDARY OUTCOME MEASURES

Acid-base balance in cord artery blood and Apgar score <7 at 5 minutes.

RESULTS

Median lactate concentrations in the SGA, AGA and LGA groups were 3.8, 3.0 and 2.2 mmol/l, respectively (SGA versus AGA, P = 0.017; LGA versus AGA, P = 0.009). In the subgroups with scalp lactate >4.8 mmol/l (lactacidaemia), the corresponding median (range) values were 6.2 (4.9-14.6), 5.9 (4.9-15.9) and 5.7 mmol/l (5.0-7.9 mmol/l), respectively (no significant differences between the groups). The proportions of neonates with cord artery pH < 7.00, metabolic acidaemia or Apgar score <7 at 5 minutes were similar in all weight groups.

CONCLUSION

SGA fetuses with fetal heart rate abnormalities have the same ability to produce lactate as a response to intrapartum hypoxia as AGA and LGA fetuses. The risk of a poor outcome associated with high lactate concentration is the same in SGA, AGA and LGA fetuses. Scalp blood lactate analysis is therefore a reliable method for intrapartum fetal surveillance of suspected growth-restricted fetuses scheduled for vaginal delivery at ≥ 34 weeks of gestation.