Introduction

Placental abruption is one of the conditions in pregnancy that poses a major threat to the pregnant person and baby. The consequences of the condition can bring the excitement of pregnancy to an abrupt end. Placental abruption is the complete or partial separation of a normally sited placenta from the uterine wall before delivery.¹

It is a potential complication in the second half of pregnancy and a major emergency that requires prompt intervention to save the lives of the baby and the pregnant person. Placental abruption can be either revealed or concealed. It can also be a mixture of the two. 

How does placental abruption occur?

Abruption occurs when there is bleeding between the placenta and the wall of the uterus (womb). This bleeding causes the detachment of the placenta from the wall of the womb.  Initially, the bleeding may be small in amount and may not be noticed. Over time, bleeding increases and the pressure may lead to partial or complete separation of the placenta from the attachment site.² This may remain concealed if the edge of the placenta is not separated. If the edge of the placenta separates, however, it manifests as revealed bleeding, often manifesting as vaginal bleeding.

This blood may seep into the muscles of the womb (Couvelaire uterus). It may even pass through the muscles into the abdominal cavity. The placenta is essential to the survival of the baby, therefore, the separation cuts off the blood supply to the baby, leading to a drop in oxygen. This may lead to the death of the baby. The separation of the placenta may happen so rapidly that if no intervention is instituted on time, the health of the baby and the pregnant person will be jeopardised.

Classification of placental abruption

Abruption can be classified into three different types: 

Revealed

The placenta separates and the blood collects between the placenta and the wall of the womb and then flows out through the vagina. Revealed bleeding is seen in about 80% of placental abruptions. When revealed it manifests as vaginal bleeding usually in the last trimester of pregnancy.

Concealed

The placenta separates, but the blood is retained between the placenta and the wall of the womb.

Mixed abruptio

Mixed abruptio manifests as separation of the placenta where some of the blood is trapped and some is revealed as vaginal bleeding  

Placental abruption can also be classified into four grades according to the severity.

What are the risk factors for placental abruption?

The major cause of abruption is unknown, but some risk factors have been linked to its occurrence. 

These risk factors include:

• Previous history of placental abruption
  • The rate of placental abruption recurrence is up to 19-25%
• High blood pressure
  • Chronic hypertension or preeclampsia (hypertension in pregnancy) 
  • This is the most common risk factor³
• Advanced age of the pregnant person (>35 years)
• Pregnant person less than 20 years of age
• Presence of fibroids at the  point of placental attachment
• Substance abuse
  • Cigarettes, alcohol and Illicit drugs can affect the blood supply to the placenta, increasing the risk of detachment
• Sudden reduction in the size of the womb e.g., after delivery of the first twin, a sudden reduction in the size of the womb can lead to detachment of the placenta
• Trauma: A fall or any other trauma to the abdomen increases the risk of placental detachment⁴
• Short umbilical cord
• Chorioamnionitis (Infection of the amniotic sac)
• Premature rupture of membranes (breaking of the amniotic sac), especially in cases of polyhydramnios (too much amniotic fluid)

Other risk factors include:

• Folic acid deficiency
• Thrombophilia (diseases associated with increased blood clotting)⁵
• Assigned male at birth (AMAB)
• Low socioeconomic condition

Who does placental abruption affect?

• Worldwide, placental abruption occurs in about 1% of pregnancies^6,7
• In the USA, it is commonly seen among minority racial groups like African-Americans
  • This may be due to a combination of many risk factors
• It is more common at the extremes of reproductive age, i.e. less than 20 and greater than 35 years

What are the symptoms and signs of placental abruption?

 A person with revealed abruption may report any of these symptoms: 

• Vaginal bleeding - this blood is usually dark coloured
  • Seen in about 80% of cases
• Abdominal pain may be severe and constant
  • Seen in about 70% of cases
• Rapid contraction of the muscles of the womb
• Reduced or absent movement of the baby
• Low back pain

When examined, she may have any of the following ;

• Palour - due to reduced blood volume
• Signs of shock (raised pulse rate with low blood pressure)
• Tenderness (pain on the abdomen when touched)
• Contractions
• Hard, board-like abdomen, though this is usually seen in concealed abruption
• Baby’s heart rate is abnormal or absent
• Bleeding through the cervix on vaginal examination
  • The cervix may also be dilated(open) if the patient is already in labour
  • The blood is usually dark red
• If the membrane (amniotic sac) has broken, the fluid will be port wine coloured

How is revealed placental abruption diagnosed?

The diagnosis is usually made through;

History and examination findings 

The symptoms and signs observed in abruption are usually enough to make a diagnosis.⁷

Suspicion of placenta abruption should be high in a pregnant person in the third trimester who presents with vaginal bleeding, uterine contractions and uterine hypertonus (hard, rigid uterine wall).

Ultrasound

Ultrasound is not usually helpful when diagnosing the early stages of bleeding as it is difficult to differentiate between the placenta and blood. Bleeding behind the placenta is only seen in 2-25% of abruptions. However, ultrasound helps differentiate abruption from other causes of vaginal bleeding in pregnancy. 

If the location of the placenta is unknown before the onset of bleeding, then the ultrasound scan should be done before vaginal examination.

Blood tests

Some blood tests are useful in the management of patients with abruption of the placenta:

• Full blood count - checks the blood percentage and the count of the blood cells
• Kidney function test - checks the effect of the  placental abruption on the kidneys
• Blood grouping - there may be a mixture of the baby's and the pregnant person's blood during an abruption. If the mother is rhesus-negative, she will need to receive anti-D immunoglobulin
• Clotting profile - This is used to check the effect of placental abruption on blood clotting

Monitoring of the baby’s heart rate

An abnormal foetal heart rate whena pregnant personis bleeding is suggestive of placental abruption.

Since placental abruption is not the only cause of bleeding in pregnancy, efforts should be made to rule out similar conditions.²

These include:

• Placenta praevia
• Vasa praevia
• Uterine rupture
• Vaginal injuries
• Tumours in the vagina or cervix

What are the complications of placental abruption?

Complications of placental abruption can be to the pregnant person and/or baby.

Complications to the pregnant person:

• Haemorrhagic shock (shock due to bleeding)
• Kidney failure
• Blood clotting abnormalities
• Risk of postpartum haemorrhage (bleeding after birth)³ 
• Risk of surgical intervention⁵ 
• Need for blood transfusions¹ 
• Death

Complications to the baby:

• Prematurity due to preterm delivery¹
• Low birth weight
• Stillbirth
• Birth asphyxia (lack of oxygen to the brain and other vital organs before, during or after birth)
• Newborn death

How is placental abruption managed?

Placental abruption is managed based on its severity, the age of the pregnancy, and whether the baby is alive or dead.

Mild abruption

If the abruption is mild, the pregnant person and baby are not in immediate danger. If the baby is premature and the hospital has the necessary facilities for close monitoring of both the pregnant person and the baby, the pregnant person will be admitted. Monitoring is done through serial ultrasound and observing the baby’s heart rate until the bleeding resolves. 

Severe abruption 

• This is the most common form of presentation. Revealed abruption, when severe, is an emergency and an urgent response is needed to be able to save the lives of the pregnant person and baby. Management involves immediate and definitive management:

Immediate management

The immediate response is to assess the condition of the pregnant person and baby.

If the pregnant person is in shock or the baby is in distress, the following will be done:

• Infusion of  intravenous fluid
• Collection of blood samples for urgent investigation
• Type and cross-match blood for transfusion
• Oxygen therapy

Definitive management

Definitive management involves:

• Making a birth plan
• Management of the precipitating condition

Birth plan

Depends on the condition of the mother and baby.

Vaginal delivery is the preferred option if:

• The baby is dead
• The baby is alive and the pregnant person is in advanced labour

Caesarean delivery would  be required if:

• The baby is in distress and vaginal birth is not imminent
• If the pregnant person has another condition that precludes vaginal delivery
• If there is significant ongoing bleeding

Management of precipitating conditions

This involves the management of the conditions that led to the placental abruption, like the control of hypertension if elevated.

Can placental abruption be prevented?

Though placental abruption cannot be completely prevented, some of the risk factors can be controlled or modified.

This includes:

• Proper treatment for high blood pressure and other chronic illnesses
• Avoiding smoking, alcohol, and drug use before and during pregnancy
• Regular antenatal care to detect and treat risk factors at an early stage
• Taking precautions to avoid falls and any other trauma to the abdomen

Summary

Placental abruption is a serious pregnancy complication of the third trimester. This condition can lead to severe bleeding and jeopardise the lives of both pregnant person and baby. Revealed abruption presents with symptoms such as vaginal bleeding, abdominal pain, and uterine contractions. Risk factors include hypertension, advanced age of the birthing parent, substance misuse, and trauma. The management of abruption depends on the severity and includes monitoring, fluid resuscitation, blood transfusion and possibly early delivery. Preventive measures involve managing hypertension, avoiding substance use, and ensuring regular prenatal care.