A 29-year-old woman, gravida 1 para 0, at 33 weeks gestation is an inpatient on the antepartum unit for management of known vasa previa. A few minutes ago, the patient had rupture of membranes with leakage of blood-tinged fluid. She has no contractions or heavy vaginal bleeding. The pregnancy was the result of in vitro fertilization and has otherwise been uncomplicated. A fetal growth ultrasound performed yesterday revealed a cephalic fetus with an estimated fetal weight at the 50th percentile and a normal amniotic fluid index. Temperature is 36.7 C (98.1 F), blood pressure is 110/70 mm Hg, and pulse is 70/min. Fetal heart rate is 100/min. The uterus is nontender and has no palpable contractions. Which of the following is the best next step in management of this patient?
Vasa previa | |
Definition |
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Risk factors |
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Clinical presentation |
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Management |
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FHR = fetal heart rate; ROM = rupture of membranes. | |
Normal fetal vessels travel in the umbilical cord surrounded by thick, gelatinous tissue (ie, Wharton jelly) that protects them. In contrast, vasa previa is an aberrant condition in which the fetal vessels overlie the cervix, surrounded only by thin fetal membranes, making them prone to tear with rupture of membranes or contractions. Risk factors include in vitro fertilization, as in this patient, and placenta previa.
Vasa previa is typically diagnosed on fetal anatomy ultrasound at 18-20 weeks and managed with planned cesarean delivery at 34-35 weeks gestation (ie, prior to spontaneous labor). Because total fetal blood volume is low (eg, ~250 mL or 1 cup), even minimal fetal bleeding can lead to rapid exsanguination and fetal demise. Therefore, these patients require third-trimester inpatient management to monitor for acute changes that require immediate delivery.
This patient with vasa previa and rupture of membranes likely has a ruptured fetal vessel, as evidenced by the leakage of blood-tinged vaginal fluid and fetal bradycardia. This obstetric emergency requires immediate delivery. Because vaginal delivery can cause further fetal vessel tearing and fetal compromise, induction of labor is contraindicated (Choice D). Therefore, the best next step in management is emergency cesarean delivery.
(Choice A) In patients at risk for preterm delivery, betamethasone promotes fetal lung maturity and magnesium sulfate prevents neonatal seizures. Because betamethasone requires hours to take effect, it is not typically administered to patients requiring immediate delivery because it offers minimal benefit. In addition, magnesium sulfate is not administered to patients at ≥32 weeks gestation.
(Choice B) A biophysical profile assesses for fetal hypoxia and asphyxia in high-risk patients to guide delivery timing. It does not change management of this patient who requires emergency cesarean delivery and may delay intervention, thereby risking fetal demise.
(Choice E) Prophylactic latency antibiotics (eg, erythromycin, ampicillin) are indicated in patients at <34 weeks gestation with preterm prelabor rupture of membranes to prevent fetal infection, delay delivery, and allow further fetal growth in utero. It is not indicated in patients requiring immediate delivery.
Educational objective:
Vasa previa is a rare condition in which the fetal vessels overlie the cervix, making them prone to tear and bleed with rupture of membranes or contractions. Management of a ruptured fetal vessel is with emergency cesarean delivery because of the high risk of fetal exsanguination and demise.