EFM Dumps with Practice Exam Questions Answers

Comprehensive and Detailed Explanation From Exact Extract NCC-Recommended Sources

NCC-recommended physiology references (AWHONN, Simpson & Creehan, Menihan, Creasy & Resnik) consistently state that the primary mechanism by which tachysystole affects fetal oxygenation is reduced uteroplacental perfusion, specifically through impaired intervillous space reperfusion.

During a normal contraction cycle, the fetus receives oxygen between contractions, when the uterus relaxes and maternal blood re-enters the intervillous space. AWHONN’s Fetal Heart Monitoring Principles & Practices explains that tachysystole—defined as more than five contractions in 10 minutes averaged over 30 minutes—shortens or eliminates the relaxation phase, preventing adequate placental reoxygenation.

Simpson & Creehan highlight that “tachysystole decreases uteroplacental blood flow and interferes with replenishment of oxygenated maternal blood in the intervillous space.” Menihan emphasizes that fetal hypoxemia in tachysystole results from interrupted perfusion, not from altered oxygen transport or maternal hemodynamic changes. Creasy & Resnik confirm that uterine overactivity reduces intervillous perfusion during contractions and impairs fetal oxygen exchange.

Thus, the physiologic problem is failure of the intervillous space to reperfuse, which compromises fetal oxygenation.

Comprehensive and Detailed Explanation From Exact Extract–Based NCC C-EFM References:

NCC and NICHD define baseline FHR as the mean FHR rounded to increments of 5 bpm during a minimum of a 10-minute window, excluding:

Accelerations

Decelerations

Marked variability

If a segment shorter than 10 minutes is used, it cannot be called a "baseline".

Thus the required minimum is 10 minutes.

Comprehensive and Detailed Explanation From Exact Extract–Based NCC C-EFM References:

The tracing demonstrates:

Baseline: approx. 140 bpm

Variability: minimal-to-moderate (fluctuating but not consistently moderate)

Decelerations: shallow variable decelerations

Accelerations: not consistently present

According to NICHD/NCC definitions:

Category I requires ALL of the following:

Baseline 110–160

Moderate variability

No late or variable decelerations

Early decels and accelerations may be present

This tracing does not have consistently moderate variability and does have variable decelerations, so it is not Category I.

Category III requires ANY of the following:

Absent variability with recurrent late decels

Absent variability with recurrent variable decels

Absent variability with bradycardia

Sinusoidal pattern

This tracing does not show absent variability, bradycardia, or recurrent significant lates.

Category II includes:

Minimal variability

Absence of accelerations

Variable decelerations

Tracings not clearly Category I or III

This strip fits Category II exactly due to minimal variability + intermittent variable decelerations.

Thus, the correct classification is Category II.

Comprehensive and Detailed Explanation From Exact Extract–Based NCC C-EFM References:

As gestation advances:

Vagal (parasympathetic) control increases,

Sympathetic dominance decreases,

Resulting in a lower baseline heart rate.

NCC physiology teaching:

“Baseline FHR decreases with advancing gestational age due to maturation and increasing parasympathetic tone.”

Why the others are incorrect:

Catecholamines increase heart rate, not decrease it.

Intrinsic ventricular rate does not change significantly with gestational age.

Thus, the correct physiologic factor is increased parasympathetic tone.

Comprehensive and Detailed Explanation From Exact Extract NCC-Recommended Sources

Variability is created by beat-to-beat differences in fetal cardiac intervals due to autonomic nervous system modulation. AWHONN specifies that absent variability appears as “a near-straight line with minimal or no discernible oscillations,” which occurs when all beat intervals are identical.

Menihan notes that Doppler displays variability based on mechanical motion and will show flat, unchanging intervals when fetal autonomic modulation is suppressed, reflecting absent variability.

Bradycardia refers to a baseline <110 bpm and does not describe the uniformity of intervals. A normal baseline may still show variability; it cannot have identical beat-to-beat intervals, as this violates the definition of variability in NICHD terminology.

Simpson & Creehan state that absent variability is a significant marker of impaired fetal oxygenation or CNS depression.