EFM - Electronic Fetal Monitoring Baseline Fetal Heart Rate Questions and Answers — Questions and Answers
Question 1: According to the 2008 NICHD guidelines, what is the minimum amount of identifiable baseline that must be present in a 10-minute window to determine the baseline fetal heart rate?
- At least 5 minutes, which must be contiguous.
- At least 2 minutes, which do not need to be contiguous. (Correct answer)
- The entire 10-minute segment must be stable.
- At least 1 minute, which must be contiguous.
Correct answer: At least 2 minutes, which do not need to be contiguous.
The National Institute of Child Health and Human Development (NICHD) guidelines specify that the baseline fetal heart rate is determined over a 10-minute window. To establish the baseline, there must be at least 2 minutes of identifiable baseline segments. These segments do not need to be continuous. If this minimum cannot be identified, the baseline is considered indeterminate.
Question 2: A term fetus has a baseline heart rate of 175 bpm that persists for more than 10 minutes. Which of the following is the correct classification for this baseline?
- Normal baseline
- Bradycardia
- Tachycardia (Correct answer)
- Prolonged acceleration
Correct answer: Tachycardia
Fetal tachycardia is defined as a baseline fetal heart rate greater than 160 bpm lasting for 10 minutes or longer. A normal baseline is 110-160 bpm. Bradycardia is a baseline less than 110 bpm. A prolonged acceleration is an increase in FHR that lasts for 2 minutes or more but less than 10 minutes; if it lasts 10 minutes or more, it is considered a change in baseline.
Question 3: A laboring patient's EFM tracing shows a consistent fetal heart rate of 100 bpm for the past 12 minutes, accompanied by moderate variability. Which of the following is the most likely cause for this fetal heart rate pattern?
- Maternal fever
- Fetal arrhythmia
- Post-term gestation with mature parasympathetic nervous system (Correct answer)
- Umbilical cord prolapse
Correct answer: Post-term gestation with mature parasympathetic nervous system
Fetal bradycardia is a baseline FHR less than 110 bpm. In a post-term fetus, increased vagal tone due to a mature parasympathetic nervous system can cause the baseline rate to be at the lower end of normal or mildly bradycardic. The presence of moderate variability makes severe, acute hypoxia (as seen with a cord prolapse) less likely. Maternal fever typically causes tachycardia, and while an arrhythmia could be a cause, parasympathetic maturity is a more common physiological reason for this specific pattern in a term or post-term fetus.
Question 4: A clinician is reviewing a 10-minute electronic fetal monitoring strip. For 7 minutes, the tracing is obscured by artifact. In the remaining 3 minutes, there are two separate 90-second segments of stable heart rate at 140-145 bpm without significant periodic changes. How should the baseline FHR be documented?
- Indeterminate
- 140 bpm
- 145 bpm (Correct answer)
- Normal
Correct answer: 145 bpm
To determine the baseline, there must be at least 2 minutes (120 seconds) of identifiable baseline segments in a 10-minute window. In this scenario, there are two 90-second segments, totaling 180 seconds (3 minutes) of identifiable baseline. The mean FHR is approximated to the nearest 5 bpm increment. Since the rate is stable at 140-145 bpm, it would be rounded to 145 bpm.
Question 5: Which of the following would NOT be included when determining the baseline fetal heart rate?
- Periods of marked variability (Correct answer)
- Segments between uterine contractions
- Periods of minimal variability
- Segments where the FHR is stable
Correct answer: Periods of marked variability
The baseline fetal heart rate is the mean FHR rounded to increments of 5 bpm during a 10-minute segment, EXCLUDING accelerations, decelerations, and periods of marked variability (>25 bpm amplitude). Segments with minimal or moderate variability between periodic changes are used to determine the baseline.
Question 6: A patient receiving terbutaline for uterine tachysystole develops a fetal heart rate baseline of 165-170 bpm. This change is most likely attributable to which of the following?
- Maternal hypotension
- Fetal sleep cycle
- Sympathomimetic effect of the medication (Correct answer)
- Increased vagal tone
Correct answer: Sympathomimetic effect of the medication
Terbutaline is a sympathomimetic drug (a beta-adrenergic agonist) that can cause maternal and subsequent fetal tachycardia as a side effect. Maternal hypotension and increased vagal tone would more likely cause bradycardia or decelerations. A fetal sleep cycle is typically associated with minimal variability and a stable baseline within the normal range, not tachycardia.
EFM - Electronic Fetal Monitoring Baseline Fetal Heart Rate Questions and Answers
According to the 2008 NICHD guidelines, what is the minimum amount of identifiable baseline that must be present in a 10-minute window to determine the baseline fetal heart rate?