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Cord Gas Analysis, Decision-to-Delivery Interval, and the 30-Minute Rule for Emergency Cesareans

Journal of Perinatology volume 25, pages 229–235 (2005)Cite this article

Abstract

OBJECTIVE:

Our primary objective was to examine the relationship between umbilical arterial gas analysis and decision-to-delivery interval for emergency cesareans performed for nonreassuring fetal status to determine if this would validate the 30-minute rule.

STUDY DESIGN:

For this retrospective cohort study, all cesarean deliveries performed for nonreassuring fetal status from September 2001 to January 2003 were reviewed. A synopsis of clinical information that would have been available to the clinician at the time of delivery and the last hour of the electronic fetal heart rate tracing prior to delivery were reviewed by three different maternal–fetal medicine specialists masked to outcome, who classified each delivery as either emergent (delivery as soon as possible) or urgent (willing to wait up to 30 minutes for delivery) since immediacy of the fetal condition is the key factor affecting the type of anesthesia used.

RESULTS:

Of 145 cesareans performed for nonreassuring fetal status during this period, 117 patients met criteria for entry, of which 34 were classified as emergent and 83 as urgent. Kappa correlation was 0.35, showing only fair/moderate agreement between reviewers. In the emergent group, general anesthesia was more common (35.3%, 10.8%, p=0.003), and the decision-to-delivery interval was 14 minutes shorter (23.0±15.3, 36.7±14.9 minutes, p<0.001). Linear regression showed a statistically significant relationship between increasing decision-to-delivery interval and umbilical arterial pH (r=0.22, p=0.02) and base excess (r=0.33, p<0.001) showing that delivery proceeded sooner for most of those with the worst cord gases, with a gradual improvement over time. For the 13 (11%) neonates with cord gases placing them at increased risk for long-term neurologic sequelae, the decision-to-delivery interval was 24.7±14.6 minutes (range 6 to 50 minutes), and 3/13 (23%) were classified as urgent rather than emergent.

CONCLUSION:

Electronic fetal monitoring shows considerable variation in interpretation among maternal–fetal medicine specialists and is not a sensitive predictor of the fetus developing metabolic acidosis. There is no deterioration in cord gas results after 30 minutes, and most neonates delivered emergently or urgently for nonreassuring fetal status even when born after 30 minutes have normal cord gases. The 30-minute rule is a compromise that reflects the time it takes the fetus to develop severe metabolic acidosis, our imprecision in its identification, and its rarity in the presence of nonreassuring fetal monitoring.

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Authors and Affiliations

  1. Department of Gyn-Ob, Division of Maternal–Fetal Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA

    Cynthia J Holcroft MD, Ernest M Graham MD, Abimbola Aina-Mumuney MD & Janice L Henderson MD

  2. Ross Medical School, Dominica, West Indies

    Karishma K Rai MD

  3. Department of Anesthesia, Johns Hopkins University School of Medicine, Baltimore, MD, USA

    Donald H Penning MD

Authors
  1. Cynthia J Holcroft MD
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  2. Ernest M Graham MD
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  3. Abimbola Aina-Mumuney MD
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  4. Karishma K Rai MD
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  5. Janice L Henderson MD
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  6. Donald H Penning MD
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Additional information

Statistical Consultant: Elizabeth A. Johnson, MS, Bloomberg School of Public Health, Biostatistics Department, Johns Hopkins University, USA.

Presented at the annual meeting of the Society of Obstetrical Anesthesia and Perinatology, Phoenix, AZ, USA, May 14–17, 2003.

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Holcroft, C., Graham, E., Aina-Mumuney, A. et al. Cord Gas Analysis, Decision-to-Delivery Interval, and the 30-Minute Rule for Emergency Cesareans. J Perinatol 25, 229–235 (2005). https://doi.org/10.1038/sj.jp.7211245

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