Fetal scalp blood sampling during second stage of labor – analyzing lactate or pH? A secondary analysis of a randomized controlled trial

Abstract

Background: Cardiotocography (CTG) is a widely used method for assessing fetal wellbeing during labor. It is well-known that CTG has high sensitivity but low specificity. To avoid unnecessary operative interventions, adjunctive methods such as fetal blood sampling (FBS) are used. Few studies have looked into whether FBS can be used during second stage of labor, and in that case, which of the methods (lactate or pH) are preferred. Objective: To evaluate clinical effectiveness of measuring lactate versus pH in preventing birth acidemia when FBS was performed during second stage of labor. Methods: Secondary analysis of a randomized controlled trial. Thousand three hundred and thirty-eight women with a singleton pregnancy, cephalic presentation, gestational age 34 weeks, and indication for FBS during second stage of labor were included. Main outcome measures: Metabolic acidemia (pH <7.05 and base deficit >12 mmol/l) or pH < 7.00 in cord arterial blood at birth. Secondary outcomes: A composite outcome (metabolic acidemia, pH <7 or Apgar score <4), and rates of operative deliveries. Results: Metabolic acidemia occurred in 4.1% in the lactate versus 5.1% in the pH group (relative risk (RR): 0.80; 95% confidence interval (CI): 0.48-1.35) and pH <7 in 1.4% versus 2.8% (RR: 0.51, 95% CI: 0.23-1.13). Composite outcome was found in 3.8 versus 4.9%, respectively (RR: 0.76; 95% CI: 0.46-1.26). No difference in total operative interventions was found. More cesarean deliveries were performed in the lactate group (16.5 vs. 12.4%; RR: 1.33; 95% CI: 1.02-1.74). Conclusion: When analyzing lactate or pH in fetal scalp blood during second stage of labor neonatal outcomes were comparable. The frequency of total operative interventions was similar but more cesarean deliveries were performed in the lactate group.

Effectiveness of fetal scalp stimulation test in assessing fetal wellbeing during labor, a retrospective cohort study

“…It is for debate whether pH or lactate should be preferred. A new secondary analysis showed no significant difference in neonatal outcome between the FBS fetal blood sampling, LR likelihood ratio, t confidence interval methods despite that there was a trend towards a lower number of pH < 7 and 5-min AS < 7 and 4 in the lactate arm [20].…”

Photonic Technology for In Vivo Monitoring of Hypoxia–Ischemia

“…The clinical diagnosis is performed according to the pH or, alternatively, the concentration of lactate. [8,9] The method, which operates in an invasive, discontinuous and intermittent fashion, does not provide a real picture of the clinical status of the fetus, leading to a high misclassification rate. [9,10] Spectroscopic techniques are constantly gaining ground in medical diagnostics due to their great capabilities to provide valuable information regarding the interaction of light with matter at molecular level.…”

“…[8,9] The method, which operates in an invasive, discontinuous and intermittent fashion, does not provide a real picture of the clinical status of the fetus, leading to a high misclassification rate. [9,10] Spectroscopic techniques are constantly gaining ground in medical diagnostics due to their great capabilities to provide valuable information regarding the interaction of light with matter at molecular level. [11,12] Near-infrared spectroscopy or microwave sensors have been considered as credible attractive alternatives for non-invasive monitoring of pH and lactate.…”

“…The clinical diagnosis is performed according to the pH or, alternatively, the concentration of lactate. [ 8 , 9 ] The method, which operates in an invasive, discontinuous and intermittent fashion, does not provide a real picture of the clinical status of the fetus, leading to a high misclassification rate. [ 9 , 10 ]…”

“…[ 8 , 9 ] The method, which operates in an invasive, discontinuous and intermittent fashion, does not provide a real picture of the clinical status of the fetus, leading to a high misclassification rate. [ 9 , 10 ]…”