EFM - Electronic Fetal Monitoring FHR Pattern Tier Interpretation Questions and Answers — Questions and Answers
Question 1: An EFM tracing shows a baseline FHR of 135 bpm, moderate variability, accelerations with fetal movement, and no decelerations. According to the NICHD three-tier system, how should this pattern be categorized?
- Category II
- Category III
- Category I (Correct answer)
- Uninterpretable
Correct answer: Category I
This fetal heart rate tracing includes a baseline of 135 bpm (normal is 110-160), moderate variability, and an absence of late or variable decelerations. These are all components of a Category I tracing, which is considered normal and strongly predictive of a normal fetal acid-base status.
Question 2: Which of the following FHR patterns is classified as a Category III tracing?
- Absent variability with recurrent late decelerations (Correct answer)
- Moderate variability with recurrent late decelerations
- Fetal tachycardia with minimal variability
- A prolonged deceleration lasting 4 minutes
Correct answer: Absent variability with recurrent late decelerations
A Category III tracing is defined by either a sinusoidal pattern OR absent baseline variability with recurrent late decelerations, recurrent variable decelerations, or bradycardia. The other options, while not normal, fall into the indeterminate Category II.
Question 3: A 20-minute EFM strip shows a baseline FHR of 170 bpm. Variability is minimal (amplitude range of 3-5 bpm). There are no accelerations or decelerations. Based on the three-tier FHR interpretation system, this tracing should be classified as:
- Category I
- Category II (Correct answer)
- Category III
- Normal variant
Correct answer: Category II
This tracing falls into Category II. The presence of tachycardia (baseline >160 bpm) and minimal variability are features of a Category II tracing. It does not meet the criteria for Category I (which requires a normal baseline and moderate variability) or Category III (which requires absent variability with recurrent decelerations, or a sinusoidal pattern).
Question 4: A clinician has classified a fetal heart rate tracing as Category II. Which of the following findings, on its own, would be consistent with this classification?
- Moderate variability with no decelerations
- Sinusoidal pattern
- Marked variability (Correct answer)
- Absent variability with recurrent variable decelerations
Correct answer: Marked variability
Marked variability (amplitude range >25 bpm) is an example of a finding that places a tracing into Category II. Moderate variability with no decelerations is a feature of Category I. A sinusoidal pattern or absent variability with recurrent variable decelerations would classify the tracing as Category III.
Question 5: An EFM tracing shows a baseline of 125 bpm. Over the last 30 minutes, there have been recurrent late decelerations. However, variability has remained moderate throughout this period. What is the correct interpretation of this FHR pattern?
- Category I, as variability is moderate.
- Category II, due to the recurrent late decelerations with moderate variability. (Correct answer)
- Category III, as any recurrent late deceleration is abnormal.
- Category I, because the baseline is normal.
Correct answer: Category II, due to the recurrent late decelerations with moderate variability.
According to the NICHD guidelines, recurrent late decelerations in the presence of moderate variability classify a tracing as Category II. The pattern only becomes Category III if the recurrent late decelerations are accompanied by absent baseline variability. The presence of moderate variability is a key factor that prevents this from being a Category III tracing.
Question 6: What is the primary goal of classifying a fetal heart rate tracing into one of the three tiers?
- To diagnose the specific cause of fetal distress.
- To predict the exact Apgar scores at birth.
- To provide a standardized framework for communication and guide clinical action based on the predicted fetal acid-base status. (Correct answer)
- To determine the precise timing for an amnioinfusion.
Correct answer: To provide a standardized framework for communication and guide clinical action based on the predicted fetal acid-base status.
The three-tier system is designed to standardize the interpretation and communication of FHR patterns. Each category is predictive of the fetal acid-base status at the time of observation, which helps guide clinical management, such as continued observation (Category I), further evaluation and intrauterine resuscitation (Category II), or prompt intervention (Category III).
EFM - Electronic Fetal Monitoring FHR Pattern Tier Interpretation Questions and Answers
An EFM tracing shows a baseline FHR of 135 bpm, moderate variability, accelerations with fetal movement, and no decelerations.
According to the NICHD three-tier system, how should this pattern be categorized?