A G1P0 woman at 38 weeks gestation undergoes induction of labor with oxytocin. Cardiotocography shows a baseline FHR of 145 bpm, moderate variability, no accelerations for 40 minutes, and three late decelerations in 20 minutes with return to baseline within 30 seconds. According to NICHD classification, this CTG is categorized as:
- A Category I (Normal) — routine monitoring
- B Category III (Abnormal) — requires prompt evaluation and delivery ✓
- C Category II (Indeterminate) — intensified monitoring warranted
- D Category II with sinusoidal pattern — immediate delivery
Explanation
NICHD Category III (Abnormal) includes: sinusoidal pattern, or any of the following with absent variability — recurrent late decelerations, recurrent variable decelerations, or bradycardia. Recurrent late decelerations (occurring in ≥50% of contractions in a 20-minute window) with absent baseline variability would be Category III. In this case, if variability is absent despite what appears to be moderate — the absence of accelerations for 40 minutes combined with recurrent late decelerations indicates a high-risk pattern. Recurrent late decelerations alone with absent variability = Category III requiring immediate intervention including intrauterine resuscitation and preparation for expedited delivery. Category II encompasses all tracings not Category I or III.
Reference: Williams Obstetrics, 26th ed.
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Written and medically reviewed by the StethoPrep medical team.