Intrauterine Asphyxia: Clinical Implications for Providers of Intrapartum Care

Jenifer Fahey, CNM, MSN, MPH; Tekoa L. King, CNM, MPH

Disclosures

J Midwifery Womens Health. 2005;50(6):498-506. 

In This Article

Recommendations for Practice and Documentation

The following are suggested guidelines for practice and documentation relevant to intrauterine asphyxia that incorporate the information presented above.

All fetuses should be monitored in labor via periodic assessment of the fetal heart rate. The modality, frequency, and timing of monitoring will vary, depending on the woman's health, the fetus' health, and the birth setting. Women at high risk for adverse perinatal outcome (e.g., maternal hypertension, intrauterine growth restriction, multiple gestation, insulin-dependent diabetes, oligohydramnios, and prematurity) should be monitored either with continuous EFM or with increased frequency of intermittent auscultation during labor (e.g., every 15 minutes in first stage, every 5 minutes in second stage, or per institutional protocol). If a woman is undergoing intermittent monitoring, and there are significant changes in the baseline, decelerations are noted, or fetal arrhythmias are detected, closer assessment of the fetal heart rate is warranted. Depending on the variation in fetal heart rate and the setting, this closer assessment may be either increased frequency and duration of auscultation or continuous EFM until fetal well-being is established.

Clinicians should have clear guidelines for what is considered a fetal heart rate tracing indicative of fetal well-being (normal baseline, moderate variability, presence of accelerations, and absence of decelerations). In perinatal units that function with high reliability (ability to operate technologically complex systems essentially without error over long periods of time), there usually is a clear understanding among the different members of the obstetric team regarding criteria that defines fetal well-being.[53]

In the presence of variant patterns (decelerations, decrease in variability, or changes in baseline) or in the presence of equivocal fetal heart rate tracing, further testing is warranted (scalp stimulation, vibroacoustic stimulation, or scalp pH). For clinicians in out-of-hospital settings or settings where it is not possible to obtain a recorded tracing of the fetal heart rate, the auscultated acceleration test may be an appropriate method to evaluate for the presence of accelerations.[54] Clinicians must bear in mind that this modality has been studied only as a method of antepartum surveillance, but theoretically, it is applicable in labor as well.

If fetal well-being cannot be established, clinical intervention may be warranted: repositioning of the mother, discontinuation of oxytocin, amnioinfusion (for persistent variable decelerations), tocolysis (if uterine hyperstimulation present), and physician consultation if expediting delivery (vaginal or cesarean) is anticipated. In an out-of-hospital setting, unless delivery is imminent (within minutes), transportation of the woman to a site where continuous EFM and emergency operative delivery is possible might be indicated if fetal well-being cannot be established through auscultation.

As stated by Parer and King, "perhaps the most difficult aspect of monitoring is recognizing and predicting the fetus who is at risk for asphyxial damage without excessively overcalling the situation. The crucial step in this regard is in projecting the potential for asphyxia decomposition. This requires a dynamic approach to fetal heart rate interpretation …"[30] The clinician should be attentive to changes in fetal heart rate pattern that may indicate a progression of hypoxemia to asphyxia in a fetus with a previously normal tracing. Two examples of pattern evolution that may represent a significant risk for intrapartum acidosis are 1) variable decelerations become repetitive and progressively more severe followed by an intermittent decrease or loss of variability and/or tachycardia between decelerations, or 2) the appearance of a "pencil-line" effect with a decrease in the amplitude of late decelerations, loss of variability, and baseline tachycardia.

In many institutions, the decision to obtain cord gases is made by the provider attending the birth. In settings where obtaining cord gases is feasible, Gibbs et al. suggest that cord gases should be obtained after delivery of an infant with risk factors for neonatal encephalopathy.[55] The decision to obtain cord gases must be weighed by the individual clinician against the potential benefits to delayed cord clamping, particularly in the preterm infant (higher hematocrit and hemoglobin levels, increased blood pressure, increased blood volume, fewer days of oxygen and ventilation, and decreased need for transfusions).[56]

Examination of the placenta can be helpful in establishing nonhypoxic and/or antepartum causes of neonatal encephalopathy and/or cerebral palsy. In addition to a thorough gross examination of the placenta at the time of delivery, a microscopic examination of the placenta by a pathologist should be considered in cases where there are antepartum risk factors for neonatal encephalopathy or cerebral palsy.

Avoid the use of ambiguous and/or imprecise terminology such as "fetal distress" and "birth asphyxia." ACOG promotes a full description of findings (e.g., "repetitive late decelerations with loss of variability and fetal tachycardia in the 170s") and interpretation of fetal heart rate patterns as "reassuring" or "nonreassuring" followed by documentation of the management plan.[57]

To ensure consistency in documentation, communication among providers is essential and should include, whenever possible, members of the neonatology team. It is especially important that providers be consistent and accurate in their communications with patients.

All providers should avoid attributing neurologic dysfunction in the neonate (including neonatal encephalopathy and cerebral palsy) to intrapartum events unless the criteria delineated by the ACOG/AAP task force have been met.

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