Interpreting the fetal heart rate tracing. Effect of knowledge of neonatal outcome

To determine if knowledge of neonatal outcome influences obstetricians' retrospective interpretation of fetal heart rate monitor tracings and opinion on the appropriateness of obstetric care.

Ten obstetric case histories that involved a critical judgment by the managing obstetrician were selected for this study. Each case contained a point in the patient's labor at which the physician made a judgment regarding route and timing of delivery. We assembled prenatal history, labor course, delivery, fetal heart rate tracing and neonatal outcome into a concise format. For each case, we created a sham case with identical information and monitor tracing, differing only in having an opposite neonatal outcome. Reviewers were recruited to participate and were unaware of the true intent of the study. Reviewers evaluated tracings for: variability, late decelerations and evidence of hypoxia, and judged whether the decision regarding delivery versus continued labor had been appropriate. Reviewers evaluated the case pairs with one month's time between the true and sham outcome cases.

Thirty-six obstetricians reviewed 2 case pairs each for a total of 72 case pairs. When the alleged neonatal outcome was poor, there was a significant tendency to respond that evidence of hypoxia was present (P = .007) or that the obstetrician had made an incorrect decision (P < .001).

Obstetricians are biased by knowledge of poor neonatal outcome when retrospectively interpreting fetal heart rate tracings and judging appropriateness of obstetric care.