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Difficulty: MediumObstetric Complications

A 31-year-old woman, gravida 2, para 1, is evaluated in the labor and delivery ward at 38 weeks of gestation. She reports regular, painful uterine contractions. Her prenatal course was notable for a second-trimester ultrasound showing a succenturiate placental lobe. On admission, her blood pressure is 116/74 mm Hg, and her heart rate is 84/min. The fetal heart rate tracing demonstrates a baseline of 145/min with moderate variability and no decelerations. Cervical examination reveals 5 cm dilation and 80% effacement with a bulging amniotic sac. The attending physician performs an artificial rupture of membranes to augment labor. Immediately following the procedure, the patient experiences a sudden gush of bright red vaginal bleeding. The patient reports no new abdominal pain. Simultaneously, the fetal heart rate drops abruptly to a baseline of 70/min and remains there for 4 minutes. The patient is awake, alert, and expresses concern about the baby's status. Which of the following is the most appropriate next step in management?

  1. A
    Maternal repositioning and intravenous fluid bolus
  2. B
    Transcervical amnioinfusion
  3. Emergency cesarean deliveryAnswer
  4. D
    Routine observation for normal bloody show
  5. E
    Defer operative consent to the patient's health care proxy

Answer

The correct answer is to proceed with an emergency cesarean delivery.
The patient's presentation of sudden, painless vaginal bleeding and acute fetal bradycardia immediately after an amniotomy is the classic presentation of a ruptured vasa previa. A succenturiate placental lobe is a major risk factor, as fetal vessels often connect the lobes through the membranes. Because the bleeding originates from the fetus, exsanguination occurs rapidly, resulting in profound fetal distress. The only appropriate life-saving intervention is an immediate emergency cesarean delivery.

Step-by-Step Solution

1
Analyze the clinical presentation and timing of symptoms.
The patient developed sudden, painless vaginal bleeding accompanied by acute fetal bradycardia immediately following artificial rupture of membranes.
Establishing the precise sequence of events (amniotomy followed by bleeding and fetal distress) is critical for diagnosis.
2
Identify relevant risk factors from the patient's prenatal history.
The patient has a known succenturiate placental lobe.
A succenturiate lobe significantly increases the risk of fetal blood vessels traversing the amniotic membranes (vasa previa).
3
Synthesize the findings to determine the most likely diagnosis.
The combination of a succenturiate lobe, amniotomy, sudden painless bleeding, and immediate fetal bradycardia strongly indicates a ruptured vasa previa.
Rupture of unprotected fetal vessels leads to rapid fetal exsanguination, which causes sudden and prolonged fetal heart rate decelerations or bradycardia.
4
Select the definitive management strategy based on the diagnosis.
Emergency cesarean delivery must be performed immediately.
Fetal blood volume is very small, and hemorrhage from ruptured vasa previa is rapidly fatal unless the fetus is delivered expeditiously.

Key Concept

Vasa previa classically presents with sudden, painless vaginal bleeding and acute fetal distress (e.g., bradycardia) immediately following the rupture of membranes, necessitating emergency cesarean delivery to prevent fetal exsanguination.
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Topics

Obstetric Complications

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