Placental disease, placenta previa, and accreta risk

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.