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Difficulty: HardObstetric Complications

A series of pregnant patients present to the labor and delivery unit, and their continuous fetal heart rate (FHR) tracings are evaluated. Based on the clinical presentation and tracing characteristics, match each intrapartum scenario with its most likely underlying pathophysiology.

  • A smooth, sine wave-like FHR baseline with a frequency of 3 to 5 cycles per minute and absent variability, presenting immediately following artificial rupture of membranes.Profound fetal anemia and hemorrhage (e.g., ruptured vasa previa)
  • Recurrent, abrupt decreases in FHR (drop of ≥ 15 bpm lasting ≥ 15 seconds) that vary in onset, depth, and duration relative to uterine contractions in a patient with oligohydramnios.Transient occlusion of umbilical blood flow (e.g., umbilical cord compression)
  • Recurrent, gradual decreases in FHR with the nadir occurring consistently after the peak of the contraction, in a patient presenting with a rigid, tender uterus and dark vaginal bleeding.Acute uteroplacental insufficiency (e.g., abruptio placentae)
  • A baseline FHR of 175 bpm with minimal variability in a patient with prolonged rupture of membranes and a maternal temperature of 39.0°C (102.2°F).Maternal-fetal systemic inflammatory response (e.g., intra-amniotic infection)

Answer

The correct matches are: L1 matches R1 (fetal anemia); L2 matches R2 (cord compression); L3 matches R3 (uteroplacental insufficiency); L4 matches R4 (intra-amniotic infection). R5 is the unmatched distractor.
Each specific FHR abnormality directly correlates with a distinct pathophysiologic mechanism. A sinusoidal pattern indicates severe fetal anemia (often from vasa previa). Variable decelerations indicate cord compression. Late decelerations point to uteroplacental insufficiency (often from placental abruption). Fetal tachycardia in a febrile mother points to intra-amniotic infection.

Step-by-Step Solution

1
Evaluate the FHR tracing and clinical context in the first scenario (smooth sine wave pattern).
Identify this as a sinusoidal pattern associated with membrane rupture.
A sinusoidal pattern indicates severe fetal anemia/hypoxia, classically occurring with fetal hemorrhage from ruptured vasa previa.
2
Analyze the FHR tracing in the second scenario (abrupt, recurrent drops in FHR).
Identify these as variable decelerations.
Variable decelerations are caused by umbilical cord compression, which is highly prevalent in patients with decreased amniotic fluid (oligohydramnios).
3
Assess the FHR tracing in the third scenario (gradual FHR drops with delayed nadir).
Identify these as late decelerations in the setting of placental abruption.
Late decelerations reflect transient fetal hypoxemia caused by uteroplacental insufficiency, which perfectly aligns with the clinical signs of a rigid, tender uterus.
4
Evaluate the FHR baseline in the fourth scenario (baseline FHR 175 bpm).
Identify this as fetal tachycardia in a febrile patient.
Prolonged rupture of membranes and maternal fever causing fetal tachycardia point directly to an intra-amniotic infection.

Key Concept

Integration of classic fetal heart rate (FHR) tracing abnormalities with maternal clinical signs to accurately diagnose underlying intrapartum obstetric complications.
Estimated Time:2m 0s
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Topics

Obstetric Complications

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