EFM Certified - Electronic Fetal Monitoring Questions and Answers

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

Whenever a fetal heart rate is unexpectedly low (such as 90 bpm), the FIRST step per NCC and AWHONN is to confirm that the signal is fetal, not maternal.

Even internal spiral electrodes can capture maternal heart rate, especially after:

Rupture of membranes

Maternal hypotension

Maternal dehydration

Maternal tachycardia or bradycardia

Thus, the first, most immediate action is:

→ Palpate the maternal radial pulse to determine whether the tracing is maternal or fetal.

If rates match → the monitor is falsely detecting the maternal pulse.

If rates differ → confirm true fetal bradycardia and begin intrauterine resuscitation.

Why the other options are incorrect:

A. Intrauterine resuscitation — should NOT begin before confirming the tracing is fetal.

C. Bedside ultrasound — appropriate after confirming that the tracing is not maternal, not before.

Correct answer: B. Palpation of the maternal radial pulse.

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.

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

Sustained fetal supraventricular tachycardia (SVT) often produces heart rates > 200–240 bpm, causing:

Poor ventricular filling

Decreased stroke volume

Reduced cardiac output

Congestive heart failure

Progressive fluid accumulation

NCC and AWHONN emphasize that untreated SVT leads to hydrops fetalis, characterized by:

Ascites

Pleural effusion

Pericardial effusion

Skin edema

Why the other answers are incorrect:

A. Fetal anemia — Causes tachycardia but is not caused by SVT.

C. Neonatal pacemaker — Pacemakers treat heart block, not SVT.

Correct answer: B. Hydrops fetalis

Comprehensive and Detailed Explanation From Exact Extract Without Links:

NCC and AWHONN teaching materials describe that butorphanol, an opioid analgesic, characteristically produces a transient sinusoidal-like pattern or pseudo-sinusoidal pattern with moderate variability preserved.

This drug-related pattern has:

• smooth, regular oscillations

• maintained variability

• absence of true periodic decelerations

• resolution within 20–60 minutes

Simpson & Menihan describe butorphanol as producing a “saw-tooth, wavering pattern” often mistaken for dysrhythmia but actually benign.

True sinusoidal patterns (e.g., fetal-maternal hemorrhage) are fixed, smooth, non-variable patterns with absent variability, not matching the scenario.

Atrial flutter produces very rapid atrial contractions, which manifest as irregular baseline spikes—also not consistent.

Therefore, the described tracing aligns most closely with butorphanol effects.

Comprehensive and Detailed Explanation From NCC-Aligned Sources:

A wandering baseline is:

A slow, fluctuating baseline

Low amplitude

No variability

No accelerations

Indicative of severe fetal neurologic injury and terminal fetal status

NCC and AWHONN describe wandering baseline as a preterminal pattern.

Why the other answers are wrong:

A. Marked variability → often transient and not associated with demise.

B. Recurrent lates → concerning but not a neurological-injury pattern unless variability absent.

Correct answer: C. Wandering baseline.

Comprehensive and Detailed Explanation From NCC-Aligned Sources:

Contraction duration is defined as the length of time from the beginning of a contraction to the end of the same contraction (NICHD uterine activity definitions).

In the diagram:

Green arrow (B) spans one individual contraction from rise → peak → return to baseline.

Blue arrow (A) measures the interval between contractions (frequency).

Red arrow (C) measures peak-to-peak amplitude shape, not duration.

Therefore, the green arrow correctly identifies contraction duration.

Comprehensive and Detailed Explanation From Exact Extract Without Links:

NCC relies heavily on ACOG Practice Bulletins for risk-based monitoring decisions. ACOG identifies maternal diabetes (pregestational or poorly controlled gestational diabetes) as a key high-risk obstetric condition warranting continuous electronic fetal monitoring due to risks such as fetal hypoxia, macrosomia, and metabolic complications.

In contrast, a history of preterm birth does not necessarily require continuous monitoring unless current pregnancy complications are present.

Macrosomia alone does not automatically justify continuous EFM unless accompanied by other risk factors.

Therefore, according to NCC-aligned ACOG clinical criteria, maternal diabetes is the correct indication.

Comprehensive and Detailed Explanation From Exact Extract (NCC C-EFM sources: AWHONN, Miller’s Pocket Guide, Menihan, Simpson, Creasy & Resnik, 2025 Candidate Guide)

AWHONN and Menihan emphasize that most fetal dysrhythmias detected intrapartum are premature atrial contractions (PACs)—the most common benign rhythm variation. They typically appear as intermittent, irregular deflections on the fetal heart rate tracing without affecting variability or baseline.

Miller’s Pocket Guide to Fetal Monitoring states that PACs are usually transient, self-limiting, and require only observation unless accompanied by tachyarrhythmia or hemodynamic compromise. When variability is preserved and no repetitive pattern or sustained tachycardia occurs, no intrauterine resuscitation measures are indicated.

Simpson and Creehan describe that oxygen administration and fluid boluses are not recommended for benign dysrhythmias, as they do not improve fetal conduction patterns and may contribute to unnecessary interventions.

The NCC 2025 Candidate Guide specifies that correct management requires distinguishing benign arrhythmias from pathologic tachyarrhythmias, which would require escalation. In the absence of fetal compromise or maternal pathology, the appropriate action is continued observation.

Therefore, the correct management is to continue to observe.

Comprehensive and Detailed Explanation From Exact Extract NCC-Recommended Sources

Sentinel events are defined by the Joint Commission as unexpected occurrences involving death, serious physical or psychological injury, or the risk thereof, and they require immediate investigation, root-cause analysis, and institutional response. They do not require confirmed malpractice or negligence.

AWHONN’s perinatal safety guidelines and NCC’s Professional Issues domain specify that sentinel events trigger mandatory reporting, analysis, system review, and corrective action plans. Simpson & Creehan emphasize that they are addressed through standardized safety processes, including interdisciplinary review.

Miller’s Pocket Guide notes that sentinel events are “events that require immediate investigation to prevent recurrence,” aligning with answer choice B.

Comprehensive and Detailed Explanation From Exact Extract (NCC-Referenced Sources)

AWHONN and Menihan clearly state that classification of decelerations is determined by their timing relative to uterine contractions:

Early decelerations: “mirror the contraction; onset, nadir, and recovery occur simultaneously with the contraction.”

Late decelerations: “begin after the contraction begins and return to baseline after the contraction ends.”

Depth is not a differentiating feature, as both early and late decelerations may vary in depth. The onset-to-nadir interval is used to differentiate variable vs. early/late, not early vs. late.

Thus, timing relative to contractions is the correct NCC-supported answer.

Comprehensive and Detailed Explanation From NCC-Aligned Sources:

Second-stage bradycardia with moderate variability most commonly occurs from:

Vagal stimulation caused by head compression, particularly during descent and pushing.

Moderate variability indicates:

Neurologically intact fetus

Sufficient oxygen reserve

Temporary nature of bradycardia

This aligns with physiologic vagal slowing rather than hypoxic mechanisms.

Why the incorrect answers are wrong:

A. Cord compression → typically produces variable decelerations, not sustained bradycardia with preserved variability.

C. Vasospasm → associated with late decelerations and decreased variability (uteroplacental insufficiency).

Correct answer: B. Vagal stimulation

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

The tracing shows tachysystole with emerging late decelerations and minimal variability:

5 contractions in 10 minutes

Deceleration nadirs occur after the peak of the contraction (late pattern)

Variability begins to trend toward minimal

The tracing has deteriorated while on oxytocin 8 mU/min, a common threshold for overstimulation

NCC and AWHONN emphasize that when tachysystole occurs with any fetal intolerance, the first action is to reduce or stop oxytocin.

Key NCC principles:

Late decelerations + tachysystole = uteroplacental insufficiency caused by excessive uterine activity

Interventions:

Stop or reduce oxytocin

Maternal repositioning

IV fluid bolus

Possible oxygen if other measures fail

Why the other options are incorrect:

A. Continue to observe — not acceptable with late decels + tachysystole.

C. Place a spiral electrode — this corrects signal quality, not uterine overstimulation or fetal oxygenation.

Thus, the best initial response is B. Decrease the oxytocin.

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

The fetal heart rate tracing demonstrates recurrent deep variable decelerations with a rapid drop in FHR, a V-shaped pattern, and slow return to baseline. These are classic signs of cord compression. According to NCC, AWHONN, Miller, Menihan, and Simpson, recurrent variable decelerations require immediate intrauterine resuscitative interventions before any decision regarding operative birth.

NCC-aligned intervention steps include:

Maternal repositioning (first-line for cord compression)

Reducing or stopping oxytocin if infusing

IV fluid bolus

Amnioinfusion (if appropriate and recurrent deep variables persist)

Oxygen only if other measures fail (per NCC/AWHONN updated guidance)

The cervix has remained unchanged at 5 cm for 3 hours (a prolonged latent or early active labor pattern), but the fetal tracing shows Category II—recurrent variable decelerations. Category II dictates corrective action, not immediate delivery unless it progresses to Category III.

Cesarean birth (option C) is reserved for:

Persistent Category III

Failure of intrauterine resuscitation

Proven fetal intoleranceNone of these conditions have been met yet.

Thus, the correct initial management is B. Perform intrauterine resuscitative measures.

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

The tracing shows a clear relationship between uterine activity and fetal heart rate changes:

The uterine activity strip demonstrates very frequent contractions with little resting time between them, exceeding five contractions in 10 minutes, averaged over a 30-minute window.

NCC and NICHD define tachysystole as “more than 5 contractions in 10 minutes, averaged over 30 minutes, regardless of whether the labor is spontaneous or stimulated.”

As uterine activity intensifies and becomes excessively frequent, the fetal heart rate strip begins to show:

Progressive decrease in baseline

Recurrent decelerations with gradual onset and recovery

Reduced variability in the latter portion of the strip

This pattern is consistent with uteroplacental insufficiency caused by excessive uterine activity (tachysystole). NCC and AWHONN emphasize that tachysystole can result in decreased uterine blood flow and fetal oxygenation, leading to late or prolonged decelerations and eventual bradycardia if not corrected.

Why the other options are less likely:

A. Placental abruptionTypically associated with maternal symptoms (pain, vaginal bleeding, firm/boardlike uterus) and often a sustained increase in resting tone or a hypertonic contraction, not simply very frequent contractions. These maternal findings are not described in the vignette.

B. Rapid fetal descentUsually causes variable or early decelerations related to head compression, but the tocodynamometer would not necessarily show this degree of contraction frequency. The lower strip here clearly highlights excessive contractions as the primary problem.

Thus, the tracing’s FHR abnormalities are best explained by tachysystole, making C. Tachysystole the most appropriate answer.

Comprehensive and Detailed Explanation From Exact Extract (No URLs):

According to AWHONN’s Fetal Assessment Text, Simpson & Miller, and Menihan, vibroacoustic stimulation is utilized during NSTs to elicit fetal accelerations, thereby minimizing testing time.

NCC-referenced sources describe VAS as:

• A method that awakens the fetus,

• Stimulates the fetal auditory system,

• Produces reactive accelerations in a neurologically intact fetus,

• Dramatically shortens NST duration, especially when the fetus is in a sleep cycle.

VAS does NOT measure amniotic fluid, nor does it have any effect on uterine activity (therefore cannot treat tachysystole).

The only correct purpose supported by NCC-cited literature is that VAS shortens the duration of the NST, making Option C correct.

Comprehensive and Detailed Explanation From NCC-Aligned Sources:

Post-dates surveillance focuses on:

Amniotic fluid volume (AFI or deepest vertical pocket)

This is the most sensitive parameter of placental function

Oligohydramnios is strongly associated with post-maturity and perinatal morbidity

NCC and AWHONN emphasize amniotic fluid as the primary parameter for fetal well-being in post-term surveillance.

Why the incorrect answers are wrong:

B. Fetal weight → inaccurate and not used for surveillance decisions.

C. Placental calcification → poor predictor of fetal outcome and not used for management.

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

Assessment of likely fetal acid–base status is grounded in NCC-aligned principles that correlate fetal pH with fetal heart rate patterns, especially variability, presence/absence of accelerations, and type and depth of decelerations.

This tracing shows the following features:

Baseline:

The fetal heart rate baseline is approximately 140–150 bpm, within the normal 110–160 bpm range.

Variability:

Moderate variability is present—approximately 6–25 bpm amplitude.

Per NCC and NICHD definitions, moderate variability is strongly associated with normal fetal oxygenation and normal fetal pH > 7.20–7.25.

Accelerations:

There are occasional small accelerations, another strong indicator of normal fetal acid–base status.

Decelerations:

The tracing shows occasional variable decelerations, shallow and brief, recovering rapidly, typical of intermittent cord compression.

NCC references emphasize that intermittent, non-recurrent variables with moderate variability do not correlate with acidemia.

Uterine activity:

Contractions are present but not excessive, and fetal response remains reassuring.

Correlating tracing features with fetal pH (per NCC, AWHONN, Simpson, Menihan):

Moderate variability is the strongest intrapartum indicator of normal fetal pH.

The NICHD/NCC consensus repeatedly states that:

“The presence of moderate variability reliably predicts adequate fetal oxygenation and a fetal pH above the threshold associated with metabolic acidemia.”

Fetal pH below 7.15 is associated with:

Absent variability

Recurrent late decelerations

Recurrent deep variable decelerations

Prolonged bradycardia

None are present in this tracing.

Because the tracing demonstrates moderate variability, intermittent uncomplicated variables, and no recurrent late decelerations, the physiologic expectation is that the fetal pH remains normal, significantly above 7.15.

Therefore, the correct answer is: A (above 7.15).

Comprehensive and Detailed Explanation From Exact Extract NCC-Recommended Sources

NCC-recommended fetal assessment texts emphasize that external Doppler ultrasound may undercount very rapid fetal arrhythmias such as fetal supraventricular tachycardia (SVT). Because Doppler detects mechanical motion rather than electrical activity, the device may record only every other cardiac contraction, a phenomenon known as “half-counting.”

Menihan’s Electronic Fetal Monitoring explains that with SVT—often exceeding 200 to 260 bpm—the monitor “may display a fetal heart rate at approximately half the true atrial rate.” AWHONN teaching materials affirm that rapid, regular tachyarrhythmias may appear deceptively slower on the external monitor due to Doppler under-sampling. Simpson & Creehan note that half-counting is a recognized technical limitation and may cause clinicians to miss true tachyarrhythmias if internal monitoring is not applied.

In contrast, artifact displays irregular, inconsistent, and non-physiologic deflections. Matching the maternal pulse suggests maternal heart rate misinterpretation, not SVT.

Miller’s Pocket Guide also highlights that half-counting is “commonly seen in fetal SVT when using external Doppler due to failure to detect each rapid contraction.”

Therefore, fetal SVT most commonly appears as half the actual rate on an external fetal monitor.

Comprehensive and Detailed Explanation From Exact Extract (NCC-Referenced Sources)

According to AWHONN, Simpson, and NCC C-EFM physiologic competencies, uterine rupture commonly presents with:

Sudden prolonged deceleration

Recurrent variables

Fetal bradycardia

Possible loss of station, vaginal bleeding, maternal pain

AWHONN specifically lists:

“Prolonged deceleration is the most common initial fetal sign of uterine rupture.”

Absent variability can occur later, but it is not the most common initial pattern.

“Loss of uterine pressure” refers to loss of toco signal, not a fetal heart rate characteristic.

Therefore, NCC-validated interpretation: prolonged and variable decelerations.

Comprehensive and Detailed Explanation From NCC-Aligned Sources:

This tracing shows:

Baseline ~170–175 bpm → fetal tachycardia

Minimal variability

No contractions of significance

Maternal treatment with magnesium sulfate, which typically decreases baseline and variability—not increase it

NCC and AWHONN physiology guidelines emphasize that fetal tachycardia is most commonly associated with maternal infection, including chorioamnionitis, especially in preterm labor.

Magnesium sulfate does not cause tachycardia; it generally causes:

↓ baseline

↓ variability

Thus, fetal tachycardia + minimal variability in a preterm patient strongly suggests maternal infection, requiring evaluation for chorioamnionitis.

Why the wrong answers are incorrect:

A. Acetaminophen → used after confirming fever, not before evaluating the cause.

B. Discontinuing magnesium → magnesium sulfate does not cause tachycardia; discontinuing it removes fetal neuroprotection.

Comprehensive and Detailed Explanation From NCC-Aligned Sources:

The tracing shows the classic features of variable decelerations:

Abrupt onset (<30 seconds from baseline to nadir)

Rapid drop followed by a rapid recovery

Significant variability in shape, depth, and timing

“Shouldering”—brief accelerations before or after the deceleration, typical of cord compression

The decelerations vary in appearance and timing relative to contractions

In second stage, this pattern is extremely common due to:

Recurrent cord compression during descent

Maternal pushing

Reduced amniotic fluid with advancing labor

Why the other options are incorrect:

A. Intermittent late decelerations

Late decelerations are uniform, smooth, begin after the contraction peak, and recover after the contraction ends.

This tracing shows abrupt, variable-shaped, non-uniform decels → NOT late decels.

C. Wandering baseline

A wandering baseline is a slowly fluctuating, low-amplitude, smooth, preterminal pattern.

This tracing shows an identifiable baseline with variability and clear decelerations, not wandering baseline.

Thus, the tracing is most consistent with variable decelerations.

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

NCC and AWHONN explain that Contraction Stress Testing (CST):

Has a higher rate of equivocal (“equivocal–suspicious” or “equivocal–hyperstimulation”) results

Frequently must be repeated or replaced with other tests

Requires inducing contractions, which carries risk (hyperstimulation, preterm labor, uterine rupture in scarred uterus)

NST is used more commonly because it is:

Noninvasive

Easier to perform

Has fewer contraindications

Has a lower rate of equivocal results

Why the others are incorrect:

B — CST does detect fetal compromise reliably and is NOT limited in its reporting structure.

C — A negative CST actually has very high negative predictive value for 7 days, making this answer incorrect.

Thus the correct choice is A. Higher frequency of equivocal results.

Comprehensive and Detailed Explanation From Exact Extract Without Links:

According to the NCC C-EFM Content Outline and AWHONN Fetal Heart Monitoring Principles, recurrent decelerations are specifically defined as decelerations that occur with ≥50% of uterine contractions in a 20–30-minute window, but standardized interpretation guidelines used by NCC and ACOG categorize recurrent patterns based on any 30-minute evaluation period.

AWHONN (FHM 6th Ed.) explains that fetal heart patterns must be evaluated over “a sufficiently long segment, typically 30 minutes, to determine whether the pattern is intermittent or recurrent.”

Menihan & Simpson further emphasize that recurrent decelerations imply a persistent physiologic stressor, requiring systematic evaluation and intrauterine resuscitation. NCC's Candidate Guide ties this rule directly into categorization within Category II and III tracings. Therefore, 30 minutes is the correct standard evaluation interval for determining recurrence.

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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 (No URLs or Links)

NCC aligns with AWHONN’s “Practice Guidelines for Fetal Heart Monitoring”, which specify the appropriate frequency of intermittent auscultation (IA) based on labor phase and risk level. For low-risk patients in active labor, IA must occur:

Every 15–30 minutes during active labor

Every 5 minutes during second stage with pushing

AWHONN and Menihan emphasize that intermittent auscultation must follow standardized time intervals to ensure adequate fetal surveillance. These intervals reflect the physiologic understanding that fetal compromise may evolve over relatively short time periods, and active labor (4–7 cm dilation) represents a time of increasing stress on fetal oxygenation.

Simpson & Creehan explain that IA frequency should increase as labor intensifies, and that the 15–30-minute interval is the nationally recognized standard for low-risk active labor. NCC’s exam content domain “Fetal Assessment Methods” reinforces knowing these surveillance intervals for safe low-intervention care.

Thus, for a 4–5 cm dilated, low-risk, spontaneous labor, the correct IA interval is every 15–30 minutes.

References (No URLs)

NCC C-EFM Candidate Guide 2025 – Fetal Assessment Methods

AWHONN Practice Guidelines for Fetal Heart Monitoring, 2022–2024

Menihan: Electronic Fetal Monitoring

Simpson & Creehan: Perinatal Nursing

Miller: Fetal Monitoring Pocket Guide

Comprehensive and Detailed Explanation From NCC-Aligned Sources:

Placental calcifications:

Reduce surface area for maternal–fetal gas exchange

Impair placental perfusion

Are associated with post-dates and chronic insufficiency

Decrease the placenta’s ability to oxygenate the fetus

Why the incorrect answers are wrong:

A. Increased maternal cardiac output → improves uteroplacental perfusion.

B. Open-glottis pushing → improves oxygenation compared with closed-glottis Valsalva pushing.

Correct answer: Placental calcifications.

Comprehensive and Detailed Explanation From NCC-Aligned Sources:

NICHD definitions:

A variable deceleration is identified by:

Abrupt onset(drop from baseline to nadir in <30 seconds)

Depth ≥15 bpm

Duration ≥15 seconds and <2 minutes

Variable timing relative to contractions

Variable shape (sharp drop, jagged descents, rapid recovery)

The scenario describes:

Abrupt drop from 125 → 80 bpm (rapid onset)

Lasting 90 seconds (still <2 minutes)

Gradual return but still within variable range

Occurring during a contraction

Depth >15 bpm

This meets ALL criteria for a variable deceleration.

Why the other options are wrong:

A. Early deceleration

Requires gradual onset (>30 seconds).

Mirrors contraction shape.

Caused by head compression.

This decel is abrupt, so NOT early.

B. Prolonged deceleration

Requires ≥2 minutes and <10 minutes.

This decel lasts 90 seconds, which is below the threshold.

Correct classification: Variable deceleration.

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

NCC physiology content specifically includes maternal autoimmune influences on fetal cardiac conduction. Conditions such as maternal lupus (SLE) or Sjogren’s syndrome may produce anti-Ro/SSA and anti-La/SSB antibodies. These antibodies cross the placenta and damage fetal conduction tissue.

The primary site of injury is the fetal atrioventricular (AV) node, leading to:

First-, second-, or complete third-degree heart block

A slow, regular ventricular rate typically 50–70 bpm

Loss of beat-to-beat variability because ventricular myocardium does not display normal autonomic modulation

This mechanism is extensively described in AWHONN, NCC physiology materials, and maternal–fetal physiology texts.

Option A: Antibodies do not target fetal RBCs; that describes hemolytic disease of the newborn.

Option B: Targeting maternal WBCs is not fetal-specific.

The correct affected structure is the fetal AV node.

Therefore, the correct answer is C. The fetal atrioventricular node.

Comprehensive and Detailed Explanation From NCC-Aligned Sources:

Normal umbilical arterial values per NCC/AWHONN/Menihan:

pH: 7.20–7.30

PaCO₂: 45–55 mmHg

HCO₃: 20–24 mEq/L

Base deficit: 0 to –5 (normal to mild respiratory changes)

This sample shows:

pH 7.25 → normal

Base deficit –4 → no metabolic acidosis

HCO₃ normal

Slightly elevated PaCO₂, consistent with mild respiratory influence but still normal

PaO₂ 20 mmHg is normal for cord arterial blood

This profile is not acidotic (acidosis requires pH <7.10 and base deficit ≥12).

It also does not indicate hypoxia, which would present with metabolic acidosis.

Therefore: Normal.

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

NCC emphasizes that only objective acid-base assessment can diagnose intrapartum asphyxia. This is accomplished with cord arterial blood gas analysis showing:

pH < 7.0–7.1

Base deficit ≥ 12 mmol/L

Elevated PCO₂

FHR patterns suggest risk, but do not diagnose asphyxia.

Apgar scores, especially at 1 minute, do not correlate reliably with acidemia.

Thus, cord gas analysis is the correct determinant.

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

On the tracing:

FHR consistently ranges 170–185 bpm.

Variability remains present, confirming adequate signal.

This pattern persists for the required minimum 10-minute baseline window.

NICHD/NCC define fetal tachycardia as:

Baseline > 160 bpm for at least 10 minutes

Because the FHR is well above 160 for the whole reviewable period, the baseline is tachycardic.

Why the other answers are incorrect:

A. 155 bpm — Too low; FHR visually averages well above this.

B. Indeterminate — Not applicable; variability is clear and the tracing meets the ≥10-minute rule.

Correct answer: C. Tachycardia

Comprehensive and Detailed Explanation From Exact Extract Sources:

The tracing demonstrates an abrupt-onset, sharp, V-shaped deceleration, occurring simultaneously with or slightly after a contraction—classic for variable decelerations, which are caused by umbilical cord compression.

According to AWHONN Fetal Heart Monitoring Principles & Practices, variable decelerations are defined by:

“Abrupt decreases in FHR below baseline of at least 15 bpm, lasting at least 15 seconds and less than 2 minutes.”

“Most commonly associated with umbilical cord compression, whether transient or recurrent.”

Physiology reference (Simpson & Miller, Pocket Guide):

Compression of the umbilical vein causes a brief acceleration.

Compression of the umbilical arteries triggers a vagal response, producing a rapid deceleration.

This creates the characteristic sharp ‘V’, ‘U’, or ‘W’ shape on the monitor.

Placental insufficiency (Choice B) produces late decelerations, which are gradual, not abrupt.

Fetal head compression (Choice A) produces early decelerations, which mirror contractions and have a gradual pattern.

Thus, the tracing is most consistent with variable decelerations caused by umbilical cord compression.

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 NCC-Recommended Sources

The tracing demonstrates a baseline within normal limits, moderate variability, and recurrent variable decelerations associated with contractions. According to NICHD/NCC definitions reproduced in AWHONN’s Fetal Heart Monitoring Principles & Practices and Menihan’s Electronic Fetal Monitoring, recurrent variable decelerations with preserved variability classify the tracing as Category II.

A Category I pattern must show baseline 110–160, moderate variability, and absence of late or variable decelerations. Because this tracing shows recurrent variable decelerations, it does not meet Category I criteria.

Category III requires absent variability PLUS recurrent late decelerations, recurrent variable decelerations, bradycardia, or a sinusoidal pattern. This tracing shows moderate variability, therefore it cannot be Category III.

Simpson & Creehan emphasize that variable decelerations reflect cord compression and fall into Category II unless accompanied by absent variability. Miller’s Pocket Guide confirms that moderate variability maintains fetal compensatory reserve, keeping the pattern in Category II.