“What now?,” she wonders.
If conservative measures do not correct the FHR tracing to the satisfaction of the clinician, it is prudent to plan ahead for the possible need for rapid delivery. In a standardized “A-B-C-D” approach to FHR management, the next step is “C”: Clear obstacles to rapid delivery. This step does not constitute a commitment to a particular time or method of delivery. It simply serves as a reminder of common sources of unnecessary delay so that they can be addressed in a standardized, timely manner (FIGURE).
Decision model for management of intrapartum fetal heart rate (FHR)Standardization has long been recognized as an essential element of patient safety, and a growing body of contemporary evidence confirms that standardization can reduce adverse outcomes and malpractice claims.8-10 In FHR monitoring, standardization can help ensure that common obstacles to rapid delivery are not overlooked and that decisions are made in a timely fashion. TABLE 3 identifies common obstacles to rapid delivery, groups them in five major categories, and organizes them in non-random order. From largest to smallest, these categories include the facility, staff, mother, fetus, and labor.
Because many of these examples are viewed by clinicians as “common sense,” they do not always receive the serious, systematic attention they deserve. Instead, they are often left to the vagaries of random recall and are frequently overlooked, jeopardizing patient safety and inviting criticism. An easy way to minimize the error inherent in random recall is to use a simple checklist and to post it in a conspicuous location on the labor-and-delivery unit.
Next step: “D” – Determine the decision-to-delivery time
After appropriate conservative measures have been implemented and obstacles to rapid delivery have been cleared away, it is sensible to take a moment to estimate the time needed to accomplish delivery in the event of a sudden emergency. This step should be addressed by the clinician who is ultimately responsible for performing operative delivery, should it become necessary. The time between decision and delivery can be estimated systematically by considering individual characteristics of the facility, staff, mother, fetus, and labor. TABLE 3 summarizes examples of factors that can have an impact on this estimate.
Clinical judgment is required
Management steps A, B, C, and D are relatively uncontroversial, readily amenable to standardization, and represent the overwhelming majority of decisions that must be made during labor. These steps do not replace clinical judgment. On the contrary, they encourage the systematic, timely application of clinical judgment.
However, if the FHR tracing has not returned to Category I by the time A, B, C, and D are completed, the clinician must make a decision about whether to continue to wait for spontaneous vaginal delivery or to expedite delivery by other means. This decision balances the estimated time until vaginal delivery against the estimated time until the onset of metabolic acidemia and potential injury.
The estimate of the time until vaginal delivery is guided by the usual obstetric considerations, including the three “P’s”:
- Power – uterine contractions
- Passenger – the fetus
- Passage – the pelvis.
The estimate of the time until the onset of metabolic acidemia and potential injury is guided by limited data suggesting that metabolic acidemia usually does not appear suddenly, but can evolve gradually over a period of approximately 60 minutes.15 This general statement applies only to FHR tracings that are normal initially and subsequently develop minimal to absent variability with recurrent decelerations and no acute events.15 It does not constitute a “safe harbor.”
The inherent imprecision of these estimates can make the decision difficult. One of the most common preventable errors at this stage of FHR management is to postpone a difficult but clinically necessary decision in the hope that the situation will resolve on its own. Despite the difficulty, the standard of care mandates that a decision must be made using the best information available.
If a decision is made to expedite delivery, the rationale should be documented, and the plan should be implemented as rapidly and safely as feasible. If a decision is made to continue to wait, the rationale and plan should be documented, and the decision should be revisited after a reasonable period of time, usually in the range of 5 to 15 minutes in the second stage of labor.
“Deciding to wait” is distinctly different from “waiting to decide.” The former reflects the timely application of clinical judgment; the latter suggests procrastination.
CASE Resolved
The OB evaluates the patient again. The FHR tracing remains in Category II. The baseline rate is 150 bpm, variability is moderate, accelerations are present, and there are variable decelerations with every other contraction. The cervix remains dilated to 6 cm despite more than 2 hours of adequate contractions. Secondary arrest of dilatation is diagnosed, and cesarean delivery is recommended. Shortly thereafter, a vigorous baby is born. As the presence of moderate variability and accelerations predicted, the 5-minute Apgar score is normal. Assessment of the umbilical artery blood gas confirms the absence of metabolic acidemia, and the newborn course is uneventful.