Bleed

Vasa Previa

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Vasa Previa, Ruptured Vasa Previa

  • See also
  1. Late Pregnancy Bleeding
  • Definitions
  1. Vasa Previa
    1. Cord velamentous membrane insertion near cervical os
    2. Fetal blood vessels cross presenting membranes
    3. Vessels may also traverse the Cervix when bridging between a bilobed placenta
  • Pathophysiology
  1. Blood loss is primarily from fetus
    1. Entire fetal Blood Volume is 300 ml at term
    2. Vasa Previa rupture may cause rapid fetal Exsanguination with high morbidity and mortality
  2. Abnormal fetal vessel insertion
    1. Fetal vessels unsupported by placenta
    2. Velamentous insertion at membranes, not at placenta
    3. Fetal vessels in membranes and tranverse Cervix
  • Epidemiology
  1. Rare cause of Late Pregnancy Bleeding
  2. Incidence: 1 in 2500 pregnancies
  • Risk Factors
  1. Low-lying placenta in second trimester
  2. In Vitro fertilization (IVF)
  3. Bilobed or succenturiate lobe of placenta
  4. Multiple Pregnancy (e.g. Twin Gestation)
  • Findings
  • Symptoms and signs
  1. Presentation
    1. Vaginal Bleeding immediately after membrane rupture
    2. Vessel may be palpable on cervical exam
  2. Fetal Distress
    1. Late Decelerations
    2. Sinusoidal Fetal Heart Rate pattern
    3. Fetal Bradycardia
  • Labs
  • Only in stable cases
  1. Modified Apt Test
  2. Wright's stain
  • Imaging
  1. Ultrasound indications
    1. Routinely on Second Trimester Ultrasound
    2. Ultrasound at 32 weeks gestation
      1. Ultrasound with placental previa (or resolved Placenta Previa)
      2. Low lying placenta
  2. Transvaginal Ultrasound with color flow doppler
    1. Differentiate from Umbilical Cord
    2. Consider in stable cases with suspected Vasa Previa
    3. Not indicated for general screening
  • Management
  • Emergent
  1. See Late Pregnancy Bleeding
  2. Heavy bleeding or non-reassuring Fetal Heart Tones
    1. Requires immediate delivery
    2. Do not delay delivery for labs or Ultrasound
  3. Immediate fluid resucitation of fetus on delivery
    1. IV or umbilical line: 10-20 cc NS bolus
  • Management
  • Routine
  1. Consult maternal fetal medicine
  2. Consider prenatal Corticosteroids if Gestational Age <34 weeks (esp. 28 to 32 weeks)
  3. Delivery by Cesarean Section at 34 to 37 weeks
  • Prognosis
  1. High perinatal mortality from fetal Exsanguination: 50%
  2. Neonatal survival without Hypoxia complications is 97% with a antenatal Vasa Previa diagnosis
    1. Vasa Previa may be diagnosed routinely on Second Trimester Ultrasound
    2. Contrast with 28% when diagnosis is delayed until after membrane rupture
  • Resources
  1. Vasa Previa Foundation
    1. http://vasaprevia.org
  • References
  1. Lee (2000) Obstet Gynecol 95:572-6 [PubMed]
  2. Sakornbut (2007) Am Fam Physician 75:1199-206 [PubMed]
  3. Yonke (2025) Am Fam Physician 112(6): 638-45 [PubMed]