Inter-observer variation in assessment of 845 labour admission tests: comparison between midwives and obstetricians in the clinical setting and two experts.

OBJECTIVE: To assess the inter-observer agreement in assessment of the labour admission test between midwives and obstetricians in the clinical setting and two experts in the non-clinical setting, the inter-observer agreement between two experts in the non-clinical setting and to what degree fetal distress in labour could be predicted by the two experts.

DESIGN: Observational study.

SETTING: The maternity unit of Hammerfest Hospital, Norway.

POPULATION: Eight hundred and forty-five high and low risk women.

METHOD: The labour admission test was first assessed by the midwife or obstetrician in the clinical setting, and was later assessed by two experts. The traces were assessed as normal, equivocal or ominous. Weighted kappa (kappaw), proportion of agreement (Pa) and predictive values were calculated.

MAIN OUTCOME MEASURES: Weighted kappa, proportion of agreement, sensitivity, positive predictive value and likelihood ratios.

RESULTS: Inter-observer agreement between Expert 1 and Expert 2: kappaw 0.38 (CI 0.31-0.46), Pa for reactive labour admission test 0.86 (CI 0.83-0.88) and Pa for equivocal/ominous test 0.33 (CI 0.26-0.40). Agreement between Expert 1 and midwives/obstetricians: kappaw 0.25 (CI 0.15-0.36), Pa for reactive labour admission test 0.89 (CI 0.87-0.91) and Pa for equivocal/ominous labour admission test 0.18 (CI 0.11-0.25). Agreement between Expert 2 and midwives/obstetricians: kappaw 0.28 (CI 0.20-0.37), Pa for reactive labour admission test 0.85 (CI 0.82-0.88) and Pa for equivocal/ominous test 0.20 (CI 0.14-0.26). Totally 5.9% of the newborns had fetal distress. At cutoff equivocal test, sensitivity was 0.22 and 0.31 in the two observers. Positive predictive values were 0.13 and 0.11. Likelihood ratio for a positive test was 2.30 and 1.92 and likelihood ratio for a negative test 0.86 and 0.83.

CONCLUSION: A labour admission test is still routine practice in most obstetric units in the Western world when there is little evidence on its benefits. The results from this study may provide some reconsideration for such practice, and for more research.