Fetal Monitoring Techniques

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Fetal Monitoring Techniques - Initial Peeks

  • Purpose: Evaluate fetal oxygenation & well-being during labor to detect hypoxia.
  • Core Methods:
    • Intermittent Auscultation (IA): Using Pinard or Doppler device.
    • Electronic Fetal Monitoring (EFM): Continuous Cardiotocography (CTG).

⭐ Intermittent auscultation (IA) is suitable for low-risk labor; continuous EFM (CTG) is for high-risk cases or if IA is abnormal.

Fetal Monitoring Techniques - Heart's Language

  • Assesses fetal well-being during labor. Key: Cardiotocography (CTG).
  • CTG Components:
    • Baseline Fetal Heart Rate (FHR): Normal 110-160 bpm.
    • Variability: Beat-to-beat FHR fluctuations.
      • Absent: Undetectable.
      • Minimal: <5 bpm.
      • Moderate: 5-25 bpm (reassuring).
      • Marked: >25 bpm.
    • Uterine Contractions: Frequency, duration.
    • Accelerations: Transient ↑ FHR by ≥15 bpm for ≥15 sec (reassuring).
    • Decelerations: Transient ↓ FHR (early, late, variable, prolonged). CTG Strip: Baseline FHR, Contractions, Variability

⭐ Moderate variability (5-25 bpm) is the most reliable indicator of fetal oxygenation and an adequately functioning fetal CNS.

Fetal Monitoring Techniques - Rises & Dips

  • Accelerations: Abrupt FHR ↑ (≥15 bpm for ≥15s if ≥32wks; ≥10 bpm for ≥10s if <32wks). Reassuring.
  • Decelerations:
    • Early: Gradual ↓, mirrors contraction. Cause: Head compression. Benign.
    • Late: Gradual ↓, nadir after contraction peak. Cause: Uteroplacental insufficiency. Ominous.
    • Variable: Abrupt ↓ (<30s onset to nadir), V/U/W shape. Cause: Cord compression.
    • Prolonged: ↓ FHR ≥15 bpm, lasts 2-10 min.
  • 📌 Mnemonic - VEAL CHOP:
    • Variable → Cord Compression
    • Early → Head Compression
    • Acceleration → OK
    • Late → Placental Insufficiency

⭐ Recurrent late decelerations signify uteroplacental insufficiency and are the most ominous pattern, strongly associated with fetal hypoxemia and acidosis.

CTG trace examples: Acceleration, Deceleration types

Fetal Monitoring Techniques - FIGO's Verdict

The International Federation of Gynecology and Obstetrics (FIGO) 2015 guidelines provide a crucial three-tier classification system (Normal, Suspicious, Pathological) for Cardiotocography (CTG) interpretation. This system, based on assessing four primary CTG features, standardizes fetal monitoring during labor and guides management decisions.

  • Baseline FHR: 110-160 bpm
  • Variability: 5-25 bpm
  • Decelerations: Type & frequency
  • Accelerations: Presence

⭐ A sinusoidal pattern on CTG, characterized by smooth, regular oscillations, is a pre-terminal sign often linked to severe fetal anemia or asphyxia.

Fetal Monitoring Techniques - Deeper Dives

  • Fetal Scalp Blood Sampling (FSBS):
    • pH/lactate for acidosis if CTG unclear.
    • Avoid: infections, bleeding risk, <34 wks.
  • Fetal ECG (STAN): ST-analysis for hypoxia; CTG adjunct.
  • Vibroacoustic Stimulation (VAS): Evokes FHR acceleration.

⭐ Fetal scalp blood pH < 7.20 or lactate > 4.8 mmol/L are critical thresholds indicating significant fetal acidosis, warranting immediate delivery.

High‑Yield Points - ⚡ Biggest Takeaways

  • Baseline FHR: 110-160 bpm; moderate variability (6-25 bpm) is reassuring.
  • Accelerations (↑15 bpm, ≥15s post-32wks) are signs of fetal well-being.
  • Early decelerations indicate head compression; late decelerations signal uteroplacental insufficiency.
  • Variable decelerations result from cord compression; often resolve with maternal position change.
  • Sinusoidal pattern is ominous, associated with severe fetal anemia or hypoxia.
  • Reactive NST: ≥2 accelerations (15x15) in 20 minutes.
  • Biophysical Profile (BPP): Score 8-10 is normal; assesses NST, breathing, movement, tone, AFI (Amniotic Fluid Index).

Practice Questions: Fetal Monitoring Techniques

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Which drug is associated with decreased fetal heart rate during labor?

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Flashcards: Fetal Monitoring Techniques

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_____ decelerations on CTG implies fetal hypoxia

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_____ decelerations on CTG implies fetal hypoxia

Late

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