Understanding Placental Problems, Diagnosis, Monitoring & Treatment

The placenta plays a vital role throughout pregnancy. It develops inside the uterus and provides oxygen and nutrients to the developing baby while helping remove waste products from the baby’s circulation.

Most pregnancies progress without significant placental problems. However, certain conditions can affect the location, attachment, blood supply, or separation of the placenta. Some of these conditions may cause vaginal bleeding, affect the baby’s growth or oxygen supply, or increase the risk of complications during delivery.

Placental problems can range from conditions that simply require additional ultrasound monitoring to situations that require urgent medical care or planned delivery in a specialist hospital.

Early identification, appropriate monitoring, and individualized delivery planning are important when a placental abnormality is suspected.

What Is the Placenta?

The placenta is a temporary organ that develops during pregnancy and attaches to the wall of the uterus.

It performs several important functions:

• Supplies oxygen to the baby
• Transfers nutrients to the baby
• Removes waste products
• Produces important pregnancy hormones
• Provides an interface between maternal and fetal circulation
• Supports fetal growth and development

The placenta is connected to the baby through the umbilical cord.

After the baby is born, the placenta normally separates from the uterine wall and is delivered as the afterbirth.

What Are Placenta Issues?

“Placenta issues” refers to a group of conditions in which the placenta:

• Is positioned unusually close to or over the cervix
• Separates from the uterus too early
• Attaches too deeply into the uterine wall
• Has abnormal blood vessels near the cervix
• Does not function adequately to support fetal growth
• Does not separate or deliver normally after birth

Some placental conditions are detected incidentally during an ultrasound, while others may present with symptoms such as bleeding, abdominal pain, contractions, or problems with fetal growth.

Common Placental Problems During Pregnancy

The major placental conditions include:

1. Low-Lying Placenta

The placenta is located close to the cervix.

2. Placenta Previa

The placenta partially or completely covers the cervix.

3. Placental Abruption

The placenta separates from the uterine wall before the baby is born.

4. Placenta Accreta Spectrum

The placenta attaches abnormally deeply into the uterine wall or surrounding structures.

5. Vasa Previa

Unprotected fetal blood vessels run through the membranes near or over the cervix.

6. Placental Insufficiency

The placenta may not provide adequate blood flow and nutrients to support expected fetal growth and well-being.

7. Retained Placenta

Part or all of the placenta does not separate and deliver normally after birth.

1. Low-Lying Placenta

A low-lying placenta means that the placenta is positioned in the lower part of the uterus and is close to the cervix.

A commonly used definition is a placental edge within 20 mm of the cervix later in pregnancy.

A low-lying placenta identified during the mid-pregnancy ultrasound does not necessarily remain low until delivery.

As the uterus grows, the relationship between the placenta and cervix usually changes, and in many pregnancies the placenta is no longer low later in pregnancy.

Why does it matter?

If the placenta remains very close to the cervix later in pregnancy, there may be an increased risk of:

• Vaginal bleeding
• Heavy bleeding
• Preterm birth
• Emergency delivery
• Difficulty with vaginal delivery

The final delivery plan depends on the placental location and the individual clinical situation.

2. Placenta Previa

Placenta previa occurs when the placenta lies over the cervix, partially or completely obstructing the normal route through which the baby would be born.

Placenta previa can cause sudden, painless vaginal bleeding, particularly during the later stages of pregnancy. The bleeding can sometimes be heavy.

Symptoms may include:

• Bright-red vaginal bleeding
• Bleeding without significant abdominal pain
• Recurrent episodes of bleeding
• Occasionally contractions

Any vaginal bleeding during pregnancy should be medically assessed.

How is placenta previa diagnosed?

Placental position is routinely assessed during the mid-pregnancy ultrasound.

If the placenta appears low, a follow-up ultrasound may be recommended later in pregnancy.

A transvaginal ultrasound may be used to accurately determine the distance between the placenta and cervix. This examination is considered safe when appropriately performed.

Can placenta previa resolve?

Yes.

A placenta that appears low in the middle of pregnancy may no longer be low later in pregnancy as the uterus grows.

Therefore, the final diagnosis and delivery plan are generally based on the placental position later in pregnancy rather than solely on the mid-pregnancy scan.

3. Placental Abruption

Placental abruption occurs when the placenta partially or completely separates from the wall of the uterus before the baby is born.

It can reduce the baby’s oxygen and nutrient supply and can cause significant maternal blood loss.

Possible symptoms include:

• Vaginal bleeding
• Sudden or persistent abdominal pain
• Back pain
• Frequent uterine contractions
• A tender or firm abdomen
• Reduced fetal movements in some cases

Importantly, visible vaginal bleeding may be absent, particularly when blood remains trapped behind the placenta.

Risk factors may include:

• High blood pressure
• Previous placental abruption
• Abdominal trauma
• Smoking
• Certain substance exposures
• Premature rupture of membranes
• Other pregnancy-related conditions

Placental abruption can also occur without an identifiable risk factor.

How is it managed?

Management depends on:

• Gestational age
• Amount of bleeding
• Maternal condition
• Fetal condition
• Severity of placental separation
• Presence of labour or other complications

If the mother or baby is unstable, urgent delivery may be required.

If the abruption is limited and both mother and baby are stable, close monitoring may sometimes be appropriate.

4. Placenta Accreta Spectrum

Placenta accreta spectrum (PAS) describes conditions in which the placenta becomes abnormally attached to or grows into the uterine wall.

The spectrum includes:

Placenta Accreta

The placenta is abnormally attached to the uterine wall.

Placenta Increta

The placenta grows more deeply into the uterine muscle.

Placenta Percreta

The placenta grows through the uterine wall and may involve nearby organs, such as the bladder.

Placenta accreta spectrum can cause severe bleeding during delivery and may require major surgical management.

Who Is at Higher Risk of Placenta Accreta Spectrum?

Important risk factors include:

• Previous caesarean delivery
• Placenta previa, particularly when combined with a previous caesarean
• Previous uterine surgery
• Certain uterine abnormalities
• Some fertility treatments
• Increasing maternal age

The risk of placenta accreta spectrum increases with the number of previous caesarean deliveries, particularly when placenta previa is also present.

Why Is Placenta Accreta Serious?

Normally, the placenta separates from the uterine wall after the baby is born.

With placenta accreta spectrum, the placenta may not separate normally.

Attempting to remove an abnormally adherent placenta can result in severe haemorrhage.

For suspected placenta accreta spectrum, delivery planning may therefore involve a multidisciplinary team, appropriate surgical expertise, anaesthesia support, and access to blood products.

How Is Placenta Accreta Diagnosed?

The primary imaging method for antenatal assessment is obstetric ultrasound, particularly when clinical risk factors are present.

Ultrasound may identify features suggesting abnormal placental attachment.

In selected cases, MRI may provide additional information, particularly when the anatomy is complex.

However, imaging does not detect every case, so the patient’s risk factors and clinical history remain important.

How Is Placenta Accreta Managed?

If placenta accreta spectrum is suspected before delivery, management should be carefully planned.

Depending on the individual situation, planning may include:

• Specialist obstetric consultation
• Detailed ultrasound assessment
• Anaesthetic planning
• Blood-bank preparation
• Multidisciplinary surgical planning
• Appropriate neonatal support
• Delivery at a suitably equipped centre

The exact surgical approach depends on the severity and location of placental invasion and the patient’s individual circumstances.

A commonly accepted approach for significant placenta accreta spectrum is planned caesarean delivery followed by hysterectomy with the placenta left in place rather than attempting forcible removal.

5. Vasa Previa

Vasa previa is a rare but potentially serious condition in which fetal blood vessels run through the membranes close to or over the cervix without the protection normally provided by the umbilical cord or placental tissue.

If these vessels rupture when the membranes break, the blood loss is from the baby, making the condition an obstetric emergency.

Risk factors may include:

• Low-lying placenta
• Multiple pregnancy
• Certain placental abnormalities
• Abnormal umbilical cord insertion

Diagnosis

Vasa previa can sometimes be identified during ultrasound, particularly with appropriate Doppler assessment.

When vasa previa is diagnosed before labour, the pregnancy can be carefully monitored and delivery planned before the membranes rupture.

The exact timing and management are individualized according to gestational age, symptoms, bleeding, and other clinical factors.

6. Placental Insufficiency

The placenta is responsible for supplying oxygen and nutrients to the developing baby.

In some pregnancies, placental function may not adequately support fetal growth and well-being.

This may be associated with:

• Fetal growth restriction
• Reduced amniotic fluid
• Abnormal Doppler findings
• Hypertension or preeclampsia
• Reduced fetal movements
• Other maternal or fetal conditions

Placental insufficiency is generally not diagnosed through one test alone. The overall clinical picture is considered.

How Is Placental Function Monitored?

Depending on the pregnancy, monitoring may include:

Ultrasound

Used to assess:

• Fetal growth
• Placental location
• Amniotic fluid
• Fetal anatomy when appropriate

Doppler Studies

Doppler ultrasound can assess blood flow through selected maternal and fetal blood vessels.

It may be particularly useful when fetal growth restriction or placental blood-flow problems are suspected.

Fetal Heart-Rate Monitoring

Depending on gestational age and clinical circumstances, tests such as NST or CTG may be recommended.

Maternal Assessment

Monitoring may include:

• Blood pressure
• Urine testing
• Symptoms
• Maternal weight
• Relevant blood investigations

The frequency of monitoring depends on the suspected condition and level of risk.

7. Retained Placenta

After delivery of the baby, the placenta normally separates from the uterus and is delivered.

A retained placenta occurs when all or part of the placenta remains inside the uterus after birth.

This can cause significant postpartum bleeding and requires prompt medical assessment.

Treatment may include:

• Medication to encourage uterine contraction
• Monitoring
• Manual removal of the placenta
• Additional procedures or surgery if necessary

The appropriate treatment depends on the patient’s condition and the cause of the retained placenta.

What Symptoms May Indicate a Placental Problem?

Placental problems do not always cause symptoms.

However, important symptoms include:

• Vaginal bleeding
• Sudden abdominal pain
• Persistent abdominal or back pain
• Uterine contractions
• Reduced fetal movements
• Feeling faint or unusually weak
• Severe pelvic discomfort
• Fluid leakage accompanied by bleeding or pain

The type of symptom can sometimes provide clues about the underlying problem, but only medical assessment can determine the cause.

Vaginal Bleeding During Pregnancy

Vaginal bleeding can occur for many different reasons.

Placental causes include:

• Placenta previa
• Placental abruption
• Vasa previa

Other causes include cervical changes, miscarriage, ectopic pregnancy, infection, and other pregnancy-related conditions.

Therefore, all significant bleeding during pregnancy should be evaluated rather than assuming that it is caused by the placenta.

When Is Placental Bleeding an Emergency?

Seek urgent medical attention if you experience:

• Heavy vaginal bleeding
• Sudden severe abdominal pain
• Persistent abdominal pain with bleeding
• Fainting or severe dizziness
• Rapid deterioration or extreme weakness
• Reduced or absent fetal movements
• Bleeding accompanied by strong contractions
• Severe pain even without visible bleeding

Placental abruption can sometimes occur without obvious vaginal bleeding, while placenta previa can cause sudden and heavy bleeding.

How Are Placental Problems Diagnosed?

Depending on the suspected condition, assessment may include:

Clinical History

Your doctor may ask about:

• Bleeding
• Pain
• Contractions
• Previous caesarean deliveries
• Previous uterine surgery
• Previous placental problems
• Medical conditions
• Pregnancy history

Physical Assessment

Your vital signs and overall condition may be assessed.

Ultrasound

Ultrasound may assess:

• Placental location
• Placental appearance
• Fetal growth
• Amniotic fluid
• Blood flow
• Possible abnormal placental attachment

Doppler Ultrasound

May be used to assess maternal and fetal circulation when clinically indicated.

Blood Tests

Depending on the situation, tests may include:

• Complete blood count
• Blood group and Rh status
• Crossmatching
• Coagulation studies
• Other investigations based on clinical circumstances

MRI

MRI may be considered in selected cases, particularly when placenta accreta spectrum is suspected and additional anatomical information is needed.

Does a Low-Lying Placenta Mean I Will Need a Caesarean?

Not necessarily.

A placenta that is low in the middle of pregnancy may move away from the cervix as the uterus grows.

If the placenta remains very close to or covers the cervix later in pregnancy, vaginal delivery may not be safe and a caesarean may be recommended.

The delivery plan is based on the placental position later in pregnancy, bleeding history, gestational age, and other individual factors.

Can Placenta Problems Be Prevented?

Not all placental conditions can be prevented.

Some risk factors cannot be changed, and placental abnormalities can sometimes occur without an identifiable cause.

However, appropriate antenatal care can help with:

• Early identification
• Risk assessment
• Appropriate ultrasound monitoring
• Management of maternal conditions
• Anaemia prevention and treatment
• Delivery planning
• Emergency preparedness when necessary

Women with previous caesarean deliveries or uterine surgery may benefit from careful assessment of placental location and attachment during pregnancy.

What Happens If I Have a Placental Problem?

The management depends entirely on the type of placental condition.

If the placenta is low:

You may require repeat ultrasound and monitoring.

If placenta previa persists:

Your doctor may recommend additional precautions and plan the safest method and timing of delivery.

If placental abruption is suspected:

Urgent assessment is required, and delivery may be necessary depending on maternal and fetal condition.

If placenta accreta is suspected:

Specialist imaging, multidisciplinary planning, blood-bank preparation, and delivery at an appropriately equipped centre may be recommended.

If vasa previa is diagnosed:

Careful monitoring and planned delivery before rupture of the membranes may be recommended.

Pregnancy and Delivery Planning With Placental Problems

The goal of management is to minimize risks to both mother and baby.

Depending on the condition, your care plan may include:

• More frequent antenatal appointments
• Repeat ultrasound examinations
• Doppler studies
• Fetal growth monitoring
• Blood tests
• Monitoring for anaemia
• Advice regarding symptoms requiring urgent assessment
• Hospital admission in selected circumstances
• Planning the timing of delivery
• Planning the mode of delivery
• Anaesthesia consultation
• Blood-bank preparation
• Neonatal team involvement where appropriate

The plan is individualized according to the specific placental condition.

Placenta Issues and High-Risk Pregnancy

Some placental conditions can make a pregnancy high-risk.

This does not mean that complications will definitely occur.

It means that the pregnancy may require:

Closer monitoring + Specialist assessment + Appropriate investigations + Careful delivery planning

Early diagnosis can help the medical team anticipate potential complications and organize appropriate care.

Why Specialist Care Matters

Placental conditions can range from relatively common findings that resolve during pregnancy to rare conditions associated with significant bleeding.

Appropriate management requires:

• Accurate diagnosis
• Understanding of the placental location
• Assessment of maternal and fetal well-being
• Identification of risk factors
• Timely repeat imaging
• Individualized delivery planning
• Access to emergency care when necessary

For suspected placenta accreta spectrum or other complex placental conditions, care may involve a multidisciplinary team with appropriate surgical, anaesthetic, neonatal, imaging, and blood-bank support.