In a fetal tracing for a suspected placental abruption, which pattern is most concerning?

• A. Early decelerations
• B. Late decelerations
• C. Accelerations only
• D. Sinusoidal pattern

Answer: (B)

Late decelerations reflect uteroplacental insufficiency, which is exactly what placental abruption causes. When the placenta isn’t delivering enough blood, the fetus becomes oxygen-starved during contractions. The heart rate drops after the contraction begins and fails to recover promptly, signaling distress from reduced placental perfusion. This pattern is the most concerning in the setting of suspected abruption because it directly indicates ongoing hypoxia that can lead to fetal acidosis if not addressed promptly.

Early decelerations happen with head compression and are usually benign, while accelerations indicate reassuring oxygenation and fetal activity. A sinusoidal pattern is also ominous and can reflect severe fetal anemia or profound hypoxia, but in the context of placental abruption, late decelerations most clearly point to impaired placental blood flow and fetal distress requiring urgent assessment.