Educational clinical resource
Placental disease, placenta previa, and accreta risk
Placental assessment considers implantation, blood flow, fetal growth, bleeding risk, prior cesarean birth, placenta previa, and possible placenta accreta spectrum.
- 01Ultrasound
- 02Placenta & growth
- 03Multiple pregnancy
- 04Prenatal genetics
How to navigate Placental disease, placenta previa, and accreta risk
An educational path from the first question to the next step. It does not replace individual assessment.
- 01Recognise the finding
Name the maternal, fetal, placental, or pregnancy concern precisely.
- 02Confirm what it means
Check gestation, diagnostic criteria, severity, and possible alternatives.
- 03Stratify risk
Identify what changes maternal safety, fetal wellbeing, timing, or prognosis.
- 04Plan surveillance
Match monitoring intensity to the condition and how quickly it can change.
- 05Escalate when needed
Refer, admit, treat, or plan birth when thresholds are reached.
Direct answer
Placental disease can affect fetal growth and maternal health through impaired function, abnormal location, or unusually deep attachment to the uterus. Placenta previa describes placenta covering or approaching the cervix. Placenta accreta spectrum (PAS) describes abnormal placental attachment or invasion and can cause life-threatening haemorrhage at delivery. These are related but not identical problems.
The most useful assessment combines clinical risk factors with expert ultrasound. A normal-looking scan does not erase a strong risk history, and an isolated ultrasound sign does not always establish PAS. Previous cesarean birth or uterine surgery, particularly with a low placenta or placenta previa, is important context.
Placental function and fetal growth
The placenta supplies oxygen and nutrients and supports the pregnancy through vascular and endocrine functions. Placental dysfunction may be associated with fetal growth restriction, hypertension or pre-eclampsia, abnormal Doppler, reduced amniotic fluid, or stillbirth risk. Surveillance is tailored to the fetal growth pattern, blood-flow findings, maternal condition, gestational age, and how quickly the picture is changing.
Placenta previa and accreta spectrum
Placental location can change as the uterus grows, so a low placenta earlier in pregnancy does not always remain low. Follow-up timing depends on the degree of proximity to the cervix, symptoms, previous surgery, and local practice.
When PAS is suspected, prenatal recognition matters because safe care may require an experienced multidisciplinary team, blood-bank preparation, specialist anaesthesia, pelvic surgical expertise, critical care, neonatology, and a planned delivery environment. MRI can be helpful in selected cases, but it does not replace expert ultrasound and clinical risk assessment.
What the report should clarify
A useful specialist report describes placental location, the relationship to the cervix and previous scar, relevant ultrasound signs, the level of suspicion, limitations of the examination, and the next review or referral step. It should avoid presenting uncertain imaging as a confirmed pathology diagnosis.
When to seek urgent assessment
Any significant vaginal bleeding in pregnancy requires clinical advice, and heavy bleeding, pain, dizziness, collapse, or feeling very unwell requires emergency assessment. Patients with known placenta previa or PAS risk should follow the hospital-specific emergency plan and should not travel without understanding where urgent care will be available.