Placenta accreta spectrum occurs when the placenta attaches too deeply into the uterine wall. Vasa praevia occurs when unprotected fetal blood vessels lie near the cervix. Both are uncommon but potentially serious and benefit from antenatal recognition and planned specialist care.

Low-lying placenta plus a previous caesarean or uterine surgery increases concern for placenta accreta spectrum.

Targeted ultrasound, sometimes supported by MRI, helps plan care but final diagnosis may only be clear at surgery.

Birth should be planned in a centre with an experienced multidisciplinary team and blood-transfusion support.

Risk factors and screening

Previous caesarean birth, placenta praevia and some uterine procedures increase accreta risk. Vasa praevia risk is associated with certain placental and cord patterns. Ultrasound teams look specifically for these features when risk is identified.

Specialist imaging and planning

Expert ultrasound evaluates placental position, vascularity and the relationship to the bladder and cervix. MRI may be useful in selected cases. The plan includes timing, surgical team, anaesthesia, blood products, neonatal care and whether hysterectomy may be required.

Shared decisions before birth

Counselling should cover haemorrhage, transfusion, critical care, fertility implications and the possibility that the operative findings differ from scans. A named point of contact and written emergency plan are valuable.

If bleeding or labour starts early

Any bleeding requires urgent hospital assessment. Patients should know which hospital to attend and whether travel away from the specialist centre is advisable later in pregnancy.

Questions worth discussing at your consultation

Which scan features suggest accreta or vasa praevia?
Where and when is birth recommended?
Which specialists and blood-bank resources will be available?
What are the possible effects on future fertility?

When to seek urgent careCall emergency services for heavy bleeding, collapse, severe abdominal pain or reduced consciousness. Any vaginal bleeding in a pregnancy with placenta praevia, accreta concern or vasa praevia requires immediate maternity assessment.

Medical note: This page is educational and is structured to support a specialist consultation. Diagnosis, investigations and treatment must be individualised. It has not been presented as a substitute for an examination or emergency assessment.