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Difficulty: MediumObstetric Complications

A 32-year-old pregnant patient, gravida 2, para 1, presents to the obstetric triage unit at 38 weeks gestation reporting painful uterine contractions. The pregnancy has been notable for an anatomy ultrasound at 20 weeks showing a succenturiate placental lobe. Her temperature is 37.0 C (98.6 F), blood pressure is 112/70 mm Hg, and pulse is 86/min. The initial fetal heart rate baseline is 145/min with moderate variability and no decelerations. Cervical examination shows 5 cm dilation and intact membranes. Three hours into her admission, the patient experiences spontaneous rupture of membranes, accompanied by a moderate amount of bright red vaginal bleeding. Immediately following this event, the fetal heart rate tracing demonstrates a prolonged deceleration that evolves into a sinusoidal pattern with a baseline of 90/min. Uterine resting tone is normal, and contractions are occurring every 3 minutes. Which of the following is the most appropriate next step in management of this patient?

  1. A
    Administration of a tocolytic agent
  2. B
    Administration of warmed amnioinfusion
  3. Immediate cesarean deliveryAnswer
  4. D
    Expectant management with continued labor monitoring
  5. E
    Emergency bedside transvaginal ultrasonography

Answer

Immediate cesarean delivery
The correct answer is immediate cesarean delivery because the clinical presentation is highly specific for a ruptured vasa previa. A succenturiate (accessory) placental lobe is a major risk factor for vasa previa, a condition where fetal blood vessels traverse the amniotic membranes across the lower uterine segment. When the membranes rupture, these unprotected fetal vessels can tear, leading to rapid fetal exsanguination. This is clinically identified by the triad of spontaneous rupture of membranes, painless vaginal bleeding, and immediate, profound fetal distress. The fetal heart rate typically shows a prolonged deceleration, bradycardia, or a sinusoidal pattern (the classic sign of severe fetal anemia). Because the fetal blood volume is extremely small, even minor vessel bleeding can be catastrophic, making emergent surgical delivery the only viable intervention.

Step-by-Step Solution

1
Identify the patient's anatomic risk factor
The patient has a succenturiate placental lobe.
This structural anomaly predisposes to vasa previa because unprotected fetal vessels often traverse the amniotic membranes between the main placenta and the accessory lobe.
2
Evaluate the acute clinical change during labor
Spontaneous rupture of membranes is immediately followed by bright red bleeding and a severe fetal heart rate decompensation (prolonged deceleration evolving into a sinusoidal pattern).
These findings represent the classic triad of ruptured vasa previa, leading to rapid fetal exsanguination and hypovolemic shock.
3
Determine the definitive next best step in management
The patient requires immediate surgical intervention.
Due to the small total blood volume of a fetus, ruptured vasa previa is a catastrophic event. Emergent cesarean delivery is the only intervention that can prevent fetal demise.

Key Concept

Vasa previa classically presents with painless vaginal bleeding and profound fetal distress (such as a prolonged deceleration, bradycardia, or sinusoidal pattern) immediately following rupture of membranes, requiring emergent cesarean delivery.
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Topics

Obstetric Complications

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