Fetal Monitoring and Fetal Distress

FHR Monitoring Basics - Heartbeat Hints

• Goal: Detect fetal hypoxia & acidosis to prevent injury.
• Methods:
  • Intermittent Auscultation (IA): Fetoscope/Doppler; for low-risk.
  • Continuous Electronic Fetal Monitoring (EFM/CTG): External (ultrasound, toco) or internal (scalp electrode, IUPC).
• FHR Control:
  • Autonomic Nervous System: Sympathetic (↑FHR), Parasympathetic (↓FHR, dominant).
  • Chemoreceptors: Respond to fetal $O_2$, $CO_2$, pH changes.
  • Baroreceptors: Respond to fetal blood pressure.

⭐ The most common cause of decreased FHR variability is fetal sleep cycle (lasting 20-40 minutes).

CTG Components - Tracing Tales

Cardiotocography (CTG) assesses fetal well-being. Key components:

• Baseline Fetal Heart Rate (FHR): Average FHR over 10 min.
  • Normal: 110-160 bpm
  • Bradycardia: < 110 bpm
  • Tachycardia: > 160 bpm
• Variability: Fluctuations in FHR around baseline.
  • Absent: Undetectable
  • Minimal: ≤ 5 bpm
  • Moderate (Normal): 6-25 bpm
  • Marked: > 25 bpm
• Accelerations: Abrupt ↑ FHR (≥15 bpm for ≥15s if ≥32w; ≥10 bpm for ≥10s if <32w). Reassuring.
• Decelerations: Transient ↓ FHR.
  • 📌 VEAL CHOP Mnemonic:
    • Variable → Cord Compression
    • Early → Head Compression
    • Acceleration → Okay
    • Late → Placental Insufficiency

![CTG tracings: early, late, variable decelerations](https://ylbwdadhbcjolwylidja.supabase.co/storage/v1/object/public/notes/L1/Anesthesiology_Obstetric_Anesthesia_Fetal_Monitoring_and_Fetal_Distress/392853b7-a98a-429e-b6e6-c4b6b7761a4f.png)

• Sinusoidal Pattern: Smooth, sine-wave like, 3-5 cycles/min, amplitude 5-15 bpm. Ominous (severe fetal anemia/hypoxia).

⭐ Late decelerations are the most ominous pattern, indicating significant fetal hypoxic stress due to uteroplacental insufficiency.

CTG Interpretation - Code Red or Green?

• Systematic approach: DR C BRAVADO (Define Risk, Contractions, Baseline Rate, Variability, Accelerations, Decelerations, Overall).
• FIGO 2015 3-Tier System:

  Category	Key Criteria
  Normal	Baseline 110-160 bpm, Variability 5-25 bpm, No repetitive decelerations. Accelerations present.
  Suspicious	One non-reassuring feature (e.g., baseline 100-109; variability <5 for 30-50 min), others normal.
  Pathological	≥2 non-reassuring, sinusoidal pattern, bradycardia <100, or prolonged deceleration >3 min.

⭐ Sinusoidal pattern is ominous, strongly associated with severe fetal anemia or hypoxia.

Fetal Distress Management - Rescue Rangers

• Non-Reassuring Fetal Status (NRFS): Clinical signs suggesting fetal hypoxia or acidosis.
• Common Causes: Placental insufficiency, cord compression, maternal hypotension, uterine tachysystole.
• Signs of Distress:
  • CTG: Pathological trace (e.g., persistent late decelerations, absent variability, bradycardia, sinusoidal pattern).
  • Meconium-stained amniotic fluid (MSAF).
  • Fetal acidosis: Scalp $pH$ < 7.20.
• Intrauterine Resuscitation (📌 LIONS):
  • Left lateral maternal position.
  • IV fluid bolus.
  • Oxygen administration (5-10 L/min via non-rebreather mask).
  • Stop uterotonics (e.g., oxytocin).
  • Consider Tocolysis (e.g., terbutaline 0.25 mg SC) if uterine tachysystole is present.
• Fetal Scalp Blood Sampling (FSBS): If NRFS persists and delivery is not imminent. $pH$ < 7.20 or $lactate$ > 4.8 mmol/L indicates significant acidosis requiring intervention.
• Urgent/Emergent Delivery: Indicated for persistent NRFS despite resuscitative measures or confirmed significant fetal acidosis.

⭐ Persistent late decelerations on CTG, especially when combined with reduced baseline variability, are highly indicative of uteroplacental insufficiency and fetal hypoxia, warranting prompt action.

High‑Yield Points - ⚡ Biggest Takeaways

• Normal FHR: 110-160 bpm. Moderate variability (6-25 bpm) is the most crucial sign of fetal well-being.
• Accelerations (↑15 bpm for ≥15s) are reassuring.
• Early decelerations indicate fetal head compression and are benign.
• Late decelerations suggest uteroplacental insufficiency and are ominous.
• Variable decelerations result from umbilical cord compression; severe ones are concerning.
• Sinusoidal pattern implies severe fetal anemia/hypoxia and is highly ominous.
• Address non-reassuring FHR patterns with intrauterine resuscitation (O2, fluids, position change).