The role of umbilical cord gas studies in the prediction of adverse neonatal outcomes in scheduled nonlaboring term singleton cesarean deliveries

Background: Most major societies do not state a specific recommendation against or in favor of routine umbilical cord gas studies sampling. Objective: We aimed to study the correlation between abnormal umbilical cord gas studies (using 5 different definitions) and adverse neonatal outcomes in scheduled nonlaboring term singleton cesarean deliveries. Study Design: The medical charts, surgical records, and neonatal charts of all singleton cesarean deliveries at 37^0/7–41^6/7 weeks of gestation between January 2009 and May 2018 from a single tertiary center were reviewed. The cohort of singleton cesarean deliveries was divided into those with “normal” vs “abnormal” umbilical cord gas studies with the 5 different definitions: (1) definition A: pH ≤7.15; (2) definition B: pH ≤7.15 and base excess ≤–12 mmol/L; (3) definition C: pH ≤7.1l (4) definition D: pH ≤7.1 and base excess ≤–12 mmol/L, and (5) definition E: pH <7.0 and base excess ≤–12 mmol/L. Adverse neonatal outcomes included Apgar scores at 5 minutes ≤7, neonatal sepsis, blood transfusion, phototherapy, respiratory morbidity (presence of respiratory distress syndrome, transient tachypnea of the newborn infant, mechanical ventilation, need for respiratory support, or meconium aspiration), cerebral morbidity (presence of intraventricular hemorrhage, seizures, or hypoxic-ischemic encephalopathy), necrotizing enterocolitis, or death. Composite adverse outcome was ≥1 of the aforementioned complications. Results: Overall, 3001 singleton cesarean deliveries were included. The rate of abnormal umbilical cord gas studies with the use of definitions A–E was 2.6%, 0.3%, 1.2%, 0.3%, and 0.1%, respectively. The overall rate of adverse neonatal outcome for the entire cohort was 14.43% (433/3001). There was no correlation between abnormal umbilical cord gas studies and composite adverse neonatal outcome with the use of any of the definitions A–E (P=.2, P=.3, P=.2, P=.3, P=.1, respectively). The sensitivity and specificity of abnormal umbilical cord gas studies as a predictor of composite adverse neonatal outcome were calculated for each of the abnormal umbilical cord gas studies definitions; although the sensitivity was extremely low (0–2.07%), the specificity was high (97.2–99.9%) Conclusion: Abnormal umbilical cord gas studies are an uncommon finding in cases of singleton term singleton cesarean deliveries and do not correlate with adverse neonatal outcomes. Therefore, the clinical usefulness and cost-effectiveness of obtaining these studies routinely should be questioned.