Makindo Medical Notes

⚠️ 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

⚠️ 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

• RCOG Green-top Guideline: Vasa Praevia
• Vasa Praevia: A Preventable Tragedy (NCBI)

💡 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.