How is fetal monitoring performed during labor?

Updated: Jan 24, 2019
  • Author: Sarah Hagood Milton, MD; Chief Editor: Christine Isaacs, MD  more...
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Answer

Often, fetal monitoring is achieved using cardiotography, or electronic fetal monitoring. Cardiotography as a form of fetal assessment in labor was reviewed using randomized and quasirandomized controlled trials involving a comparison of continuous cardiotocography with no monitoring, intermittent auscultation, or intermittent cardiotocography. This review concluded that continuous cardiotocography during labor is associated with a reduction in neonatal seizures but not cerebral palsy or infant mortality; however, continuous monitoring is associated with increased cesarean and operative vaginal deliveries. [35]

If nonreassuring fetal heart rate tracings by cardiotography (eg, late decelerations) are noted, a fetal scalp electrode may be applied to generate sensitive readings of beat-to-beat variability. However, a fetal scalp electrode should be avoided if the mother has HIV, hepatitis B or hepatitis C infections, or if fetal thrombocytopenia is suspected. Recently, a framework has been suggested to classify and standardize the interpretation of a fetal heart rate monitoring pattern according to the risk of fetal acidemia with the intention of minimizing neonatal acidemia without excessive obstetric intervention. [36]

The question of whether fetal pulse oximetry may be useful for fetal surveillance in labor was examined in a review of 5 published trials comparing fetal pulse oximetry and cardiotography with cardiotography alone. It concluded that existing data provide limited support for the use of fetal pulse oximetry when used in the presence of a nonreassuring fetal heart rate tracing to reduce caesarean delivery for nonreassuring fetal status. The addition of fetal pulse oximetry does not reduce overall caesarean deliveries. [37]

Further evaluation of a fetus at risk for labor intolerance or distress can be accomplished with blood sampling from fetal scalp capillaries. This procedure allows for a direct assessment of fetal oxygenation and blood pH. A pH of < 7.20 warrants further investigation for the fetus' well-being and for possible resuscitation or surgical intervention.

Routine laboratory studies of the parturient, such as complete blood cell (CBC) count, blood typing and screening, and urinalysis, are usually performed. Intravenous (IV) access is established.


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