Earlier and improved screening for impending fetal compromise

Area of Science:

• Obstetrics and Gynecology
• Fetal Medicine
• Neonatal Acidosis

Background:

• Fetal scalp sampling (FSS) for pH and base excess (FSSPHBE) was previously abandoned with the rise of cardiotocography (CTG).
• Understanding fetal stress tolerance in labor is crucial for developing better screening methods.
• Early identification of acidosis risk is essential for timely intervention.

Purpose of the Study:

• To investigate sequential changes in fetal pH and base excess (BE) during the first stage of labor.
• To evaluate the utility of multiples of the median (MoM's) for fetal acid-base values.
• To assess the Fetal Reserve Index (FRI) as a proxy for fetal acid-base status and its predictive capacity for acidosis risk.

Main Methods:

• Retrospective evaluation of FSSPHBE data from 475 high-risk parturients.
• Categorization of specimens by cervical dilatation (CxD).
• Development of non-parametric MoM's assessments and analysis of FRI scores and their change over time as predictors.

Main Results:

• Fetal acid-base balance (FSSPHBE) deteriorates throughout the first stage of labor.
• The interpretation of BE values is dependent on CxD, with MoM's logic enhancing understanding.
• FRI scores and their trajectory effectively screen for acidosis risk in the second stage.

Conclusions:

• Fetal acid-base reserve deteriorates early in labor, even before critical acidosis develops.
• MoM's logic aids in appreciating fetal acid-base status.
• The FRI and its trajectory serve as a suitable screening tool for early detection of fetal deterioration, enabling timely interventions.