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Vasa Praevia
⚠️ Vasa praevia is a rare but life-threatening obstetric condition in which fetal blood vessels run across (or very close to) the internal cervical os, unprotected by Wharton’s jelly. 👉 These fragile vessels can rupture during labour or rupture of membranes → rapid fetal exsanguination.
📊 Incidence
- Occurs in ~1 in 2,500–5,000 pregnancies.
- ⚠️ Fetal mortality can be up to 95% if undiagnosed, but >97% survival with antenatal diagnosis + planned caesarean.
🔎 Types
- Type 1: Vessels connect placenta → velamentous cord insertion, crossing the os.
- Type 2: Vessels run between lobes of a bilobed/succenturiate placenta across the os.
🧩 Risk Factors
- Velamentous cord insertion 🌿
- Placenta previa or low-lying placenta
- Multiple pregnancy 👶👶
- IVF conception
- Accessory placental lobes (succenturiate/bilobed)
🩺 Clinical Presentation
- Often asymptomatic if not screened antenatally.
- Bright red painless vaginal bleeding after rupture of membranes.
- 🚨 Sudden fetal bradycardia or distress during labour.
📷 Diagnosis
🏥 Antenatal detection is critical to save the fetus.
- Transvaginal ultrasound with colour Doppler → gold standard (vessels seen crossing os).
- Transabdominal scan: less sensitive.
- Vaginal exam: rarely may feel pulsating vessels (not reliable).
💊 Management
| Scenario | Key Actions | Notes |
|---|---|---|
| 👶 Antenatal diagnosis |
|
👉 Aim to avoid spontaneous ROM or labour. |
| 🚨 Unrecognised, during labour |
|
⏱️ Every minute counts – rapid exsanguination possible. |
⚠️ Complications
- Fetal mortality: extremely high if not diagnosed before labour.
- Fetal hypoxia: neurological damage, stillbirth.
📈 Prognosis
✅ With antenatal detection + elective caesarean → survival >97%. ❌ If undiagnosed → mortality 50–95%.
📚 References
💡 Teaching Pearl: Vasa praevia should always be suspected if there is painless bleeding at ROM + acute fetal bradycardia. 🧠 In exams: “normal placenta but fetal heart drops after SROM” → think vasa praevia, not placenta praevia.
| The content on this website is provided for educational and informational purposes only to support exam preparation (e.g., MLA, MRCP, USMLE) and learning. This is NOT medical advice, diagnosis, treatment, or professional guidance. It does not replace consultation with a qualified healthcare professional, official guidelines (e.g., NICE, GMC, BNF), or supervised clinical practice. Always verify information with current, authoritative sources. Makindo and its contributors accept no liability for any reliance on this content, including errors, omissions, or any resulting harm, loss, or consequences. By using this site, you agree to these terms. |
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