Umbilical lactate as a measure of acidosis and predictor of neonatal risk: a systematic review

BACKGROUND

Umbilical cord lactate is one approach to measuring acidosis and intrapartum hypoxia, knowledge of which may be helpful for clinicians involved in the care of women and newborns.

OBJECTIVE

To synthesise the evidence on accuracy of umbilical cord lactate in measuring acidosis and predicting poor neonatal outcome.

SEARCH STRATEGY

Studies published and unpublished between 1990 and 2014 from PubMed/Medline, EMBASE, Cochrane Central Register of Controlled Trials, and clinicaltrials.gov were assessed.

SELECTION CRITERIA

Cross-sectional and randomised studies that assessed fetal acidosis (using lactate as the index test) with or without an assessment of neonatal outcome.

DATA COLLECTION AND ANALYSIS

Correlations between index and reference test(s) were recorded, as were the raw data to classify the predictive ability of umbilical lactate for neonatal outcomes. Meta-analysis of correlation was performed. We plotted estimates of the studies' observed sensitivities and specificities on Forest plots with 95% confidence intervals (CI). Where possible, we combined data using meta-analysis, applying the hierarchical summary receiver operating characteristics model and a bivariate model.

MAIN RESULTS

Twelve studies were included. Umbilical lactate correlated with pH [pooled effect size (ES) -0.650; 95% CI -0.663 to -0.637, P < 0.001], base excess (ES -0.710; 95% CI -0.721 to -0.699, P < 0.001), and Apgar scores at 5 minutes (ES 0.300; 95% 0.193-0.407, P < 0.001). Umbilical lactate had pooled sensitivity and specificity for predicting neonatal neurological outcome including hypoxic ischaemic encephalopathy of 69.7% (95% CI 23.8-94.4%) and 93% (95% CI 86.8-96.3%).

AUTHORS' CONCLUSION

Umbilical cord lactate is a clinically applicable, inexpensive and effective way to measure acidosis and is a tool that may be used in the assessment of neonatal outcome.

TWEETABLE ABSTRACT

Umbilical cord lactate: a clinically applicable, inexpensive, effective way to measure intrapartum acidosis.

Application of ICD-PM to preterm-related neonatal deaths in South Africa and United Kingdom

OBJECTIVE

We explore preterm-related neonatal deaths using the WHO application of the International Classification of Disease (ICD-10) to deaths during the perinatal period: ICD-PM as an informative case study, where ICD-PM can improve data use to guide clinical practice and programmatic decision-making.

DESIGN

Retrospective application of ICD-PM.

SETTING

South Africa, and the UK.

POPULATION

Perinatal death databases.

METHODS

Descriptive analysis of neonatal deaths and maternal conditions present.

MAIN OUTCOME MEASURES

Causes of preterm neonatal mortality and associated maternal conditions.

RESULTS

We included 98 term and 173 preterm early neonatal deaths from South Africa, and 956 term and 3248 preterm neonatal deaths from the UK. In the South African data set, the main causes of death were respiratory/cardiovascular disorders (34.7%), low birthweight/prematurity (29.2%), and disorders of cerebral status (25.5%). Amongst preterm deaths, low birthweight/prematurity (43.9%) and respiratory/cardiovascular disorders (32.4%) were the leading causes. In the data set from the UK, the leading causes of death were low birthweight/prematurity (31.6%), congenital abnormalities (27.4%), and deaths of unspecified cause (26.1%). In the preterm deaths, the leading causes were low birthweight/prematurity (40.9%) and deaths of unspecified cause (29.6%). In South Africa, 61% of preterm deaths resulted from the maternal condition of preterm spontaneous labour. Among the preterm deaths in the data set from the UK, no maternal condition was present in 36%, followed by complications of placenta, cord, and membranes (23%), and other complications of labour and delivery (22%).

CONCLUSIONS

ICD-PM can be used to appraise the maternal and newborn conditions contributing to preterm deaths, and can inform practice.

TWEETABLE ABSTRACT

ICD-PM can be used to appraise maternal and newborn contributors to preterm deaths to improve quality of care.

The WHO application of ICD-10 to deaths during the perinatal period (ICD-PM): results from pilot database testing in South Africa and United Kingdom

OBJECTIVE

To apply the World Health Organization (WHO) Application of the International Classification of Diseases, tenth revision (ICD-10) to deaths during the perinatal period: ICD-Perinatal Mortality (ICD-PM) to existing perinatal death databases.

DESIGN

Retrospective application of ICD-PM.

SETTING

South Africa, UK.

POPULATION

Perinatal death databases.

METHODS

Deaths were grouped according to timing of death and then by the ICD-PM cause of death. The main maternal condition at the time of perinatal death was assigned to each case.

MAIN OUTCOME MEASURES

Causes of perinatal mortality, associated maternal conditions.

RESULTS

In South Africa 344/689 (50%) deaths occurred antepartum, 11% (n = 74) intrapartum and 39% (n = 271) in the early neonatal period. In the UK 4377/9067 (48.3%) deaths occurred antepartum, with 457 (5%) intrapartum and 4233 (46.7%) in the neonatal period. Antepartum deaths were due to unspecified causes (59%), chromosomal abnormalities (21%) or problems related to fetal growth (14%). Intrapartum deaths followed acute intrapartum events (69%); neonatal deaths followed consequences of low birthweight/ prematurity (31%), chromosomal abnormalities (26%), or unspecified causes in healthy mothers (25%). Mothers were often healthy; 53%, 38% and 45% in the antepartum, intrapartum and neonatal death groups, respectively. Where there was a maternal condition, it was most often maternal medical conditions, and complications of placenta, cord and membranes.

CONCLUSIONS

The ICD-PM can be a globally applicable perinatal death classification system that emphasises the need for a focus on the mother-baby dyad as we move beyond 2015.

TWEETABLE ABSTRACT

ICD-PM is a global system that classifies perinatal deaths and links them to maternal conditions.

Optimising the International Classification of Diseases to identify the maternal condition in the case of perinatal death

OBJECTIVE

The WHO application of the tenth edition of the International Classification of Diseases (ICD-10) to deaths during the perinatal period (ICD Perinatal Mortality, ICD-PM) captures the essential characteristics of the mother-baby dyad that contribute to perinatal deaths. We compare the capture of maternal conditions in the existing ICD-PM with the maternal codes from the WHO application of ICD-10 to deaths during pregnancy, childbirth, and the puerperium (ICD Maternal Mortality, ICD-MM) to explore potential benefits in the quality of data received.

DESIGN

Retrospective application of ICD-PM.

SETTING

South Africa and the UK.

POPULATION

Perinatal death databases.

METHODS

The maternal conditions were classified using the ICD-PM groupings for maternal condition in perinatal death, and then mapped to the ICD-MM groupings of maternal conditions.

MAIN OUTCOME MEASURES

Main maternal conditions in perinatal deaths.

RESULTS

We reviewed 9661 perinatal deaths. The largest group (4766 cases, 49.3%) in both classifications captures deaths where there was no contributing maternal condition. Each of the other ICD-PM groups map to between three and six ICD-MM groups. If the cases in each ICD-PM group are re-coded using ICD-MM, each group becomes multiple, more specific groups. For example, the 712 cases in group M4 in ICD-PM become 14 different and more specific main disease categories when the ICD-MM is applied instead.

CONCLUSIONS

As we move towards ICD-11, the use of the more specific, applicable, and relevant codes outlined in ICD-MM for both maternal deaths and the maternal condition at the time of a perinatal death would be preferable, and would provide important additional information about perinatal deaths.

TWEETABLE ABSTRACT

Improving the capture of maternal conditions in perinatal deaths provides important actionable information.