Evaluation of selection criteria for validating paired umbilical cord blood gas samples: an observational study

Authors


Dr CE Pennell, School of Women’s and Infants’ Health M550, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia. Email craig.pennell@uwa.edu.au

Abstract

Please cite this paper as: White C, Doherty D, Kohan R, Newnham J, Pennell C. Evaluation of selection criteria for validating paired umbilical cord blood gas samples: an observational study. BJOG 2012;119:857–865.

Objective  To compare six validation criteria for umbilical cord blood gas (UCBG) values in vigorous and nonvigorous neonates.

Design  Retrospective cohort study.

Setting  Single tertiary obstetric centre, King Edward Memorial Hospital (KEMH), Perth, Western Australia.

Sample  A total of 37 763 consecutive deliveries at >23 weeks of gestation.

Methods  Six validation criteria were compared to evaluate the proportion of deliveries with ‘valid’ UCBG data; and the proportion of vigorous and nonvigorous neonates with metabolic acidaemia.

Main outcomes  Proportion of deliveries with ‘valid’ UCBG values; proportions of vigorous and nonvigorous neonates with normal, borderline and abnormal UCBG values.

Results  The criteria based on KEMH 5th centile arteriovenous pH and Pco2 differences resulted in a higher proportion of neonates with ‘valid’ UCBG values than the previously described Westgate and Kro criteria. The increase in ‘valid’ UCBG values occurred across the entire study population including vigorous and nonvigorous neonates. Among neonates with short-term neonatal complications there was an increase in nonvigorous neonates with umbilical artery metabolic acidaemia. There was no corresponding increase in vigorous neonates diagnosed with abnormal UCBG values.

Conclusions  Use of the KEMH criteria results in an increase in the proportion of nonvigorous term neonates with UCBG data considered ‘valid’ to aid clinicians in the management of the neonate shortly after delivery. This change occurs without increasing the rate of false-positive diagnoses of acidaemia in vigorous neonates. The KEMH ‘validation’ criteria were developed from an entire presenting population and provide a simple algorithm that can be universally applied to identify neonates with nonphysiological UCBG values.

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