Synopsis
Recognise unprotected fetal vessels near the cervix, prevent rupture through antenatal planning, and respond immediately to bleeding accompanied by acute fetal compromise.
- Vasa praevia means fetal vessels run unprotected in membranes near or across the cervical opening.
- Type I is associated with velamentous cord insertion; type II connects placental lobes through exposed membranous vessels.
- A low placenta that later appears to resolve can coexist with persistent vessels near the cervix.
- Targeted transvaginal ultrasound with colour and pulsed Doppler distinguishes fetal vessels from maternal vascular structures.
- Confirm persistence during the third trimester because a second-trimester finding may resolve as anatomy changes.
- The published RCOG 27b pathway considers planned caesarean birth at 34–36 weeks reasonable, with individual assessment of admission and prematurity risk.
- Do not delay emergency birth for an Apt test, a repeat scan or laboratory proof that bleeding is fetal.
Key red flags
Vaginal bleeding immediately after spontaneous or artificial membrane rupture with fetal bradycardia requires emergency action for possible fetal vessel rupture.
Known vasa praevia with labour, ruptured membranes or new bleeding needs immediate hospital assessment and a senior delivery decision.
Investigation priorities
Map suspected vessels in relation to the internal os and lower membranes.
Management branches
A screening or targeted scan identifies possible vessels near the cervix.
- Refer for expert ultrasound with colour and pulsed Doppler to distinguish vasa praevia from maternal vessels or a transient cord loop.
- Record placental lobes, insertion type and the course of relevant vessels, then arrange third-trimester confirmation of persistence.
- Explain the difference between maternal bleeding and fetal vessel rupture, and give a clear instruction to contact maternity services immediately for symptoms.
Vasa praevia is confirmed and the patient remains clinically stable.
- Agree the place of care individually, considering admission from 30–32 weeks when bleeding, preterm-labour risk or access to emergency care makes it appropriate.
- Plan caesarean birth within the published 34–36-week range, adjusting for the individual balance of rupture risk and prematurity with fetal-medicine and neonatal input.
- Time corticosteroids to likely preterm birth under the current corticosteroid pathway and record a contingency plan for labour or membrane rupture before the booked date.
Key medicines
Betamethasone for anticipated preterm caesarean birthThe betamethasone sodium phosphate/acetate regimen is 12 mg intramuscularly repeated after 24 hours. Confirm the approved local schedule for phosphate-only preparations and coordinate treatment with likely birth.Diabetes requires enhanced glycaemic planning, late-preterm treatment needs an individual benefit-harm discussion, and suspected vessel rupture takes priority over steroid completion.
Neonatal emergency red-cell replacementSuspected neonatal haemorrhagic shock requires the neonatal resuscitation team's weight-based emergency transfusion prescription and compatible emergency blood; volume, rate and reassessment are determined immediately from perfusion, gestation and response.This is a neonatal rather than maternal prescription. Alert the transfusion laboratory early and do not substitute maternal crystalloid resuscitation for treatment of fetal exsanguination.