Pregnancy is a multifactorial process that involves several organs and mechanisms to continue, and when one of these factors is disrupted, the pregnancy will also be affected. 

One of these essential organs is the placenta.  The placenta can undergo a serious complication called placental abruption. This complication is a dangerous threat to both the foetus and mother and needs immediate intervention.

What is placental abruption?

The placenta is an organ that is formed only during pregnancy, attaches itself to the wall of the uterus and connects to the foetus through the umbilical cord (a tube-like structure). Its job is to provide the foetus with oxygen and necessary nutrients, in addition to removing waste from their blood.

Placental abruption is a rare but serious condition in which the placenta separates, partially or completely, from the uterine lining during pregnancy.¹ It occurs in 0.4-1% of all pregnancies, and it’s responsible for about 10% of perinatal deaths in developing countries.²

Types of placental abruption

Placental abruption can be divided into 4 types:

• Revealed placental abruption: It’s characterised by visible, moderate-to-severe vaginal bleeding
• Concealed placental abruption: The bleeding here is scarce or non-visible because the blood is trapped between the uterine wall and the placenta
• Complete placental abruption: The placenta detaches completely from the uterine wall and usually causes more vaginal bleeding
• Partial placental abruption: The placenta here doesn’t entirely detach from the uterine wall

Causes

Multiple factors relate to the occurrence of placental abruption and may manifest as a result of impaired placental function, such as preeclampsia and foetal growth restriction.¹

Placental abruption occurs due to two pathways: long-standing chronic processes and acute triggers, in addition to the interaction between them both. Chronic processes include:

• Inflammation
• Infection
• Thrombosis
• Decidual and uteroplacental vasculopathy, and they, in turn, lead to placental hypoperfusion, 
• Defective spiral artery remodelling
• Placental infarction
• Shallow trophoblast invasion

These chronic changes often occur weeks or months before the manifestations of the abruption. Sometimes genes play a role in the chronic path by causing inadequate placental attachment.³

Acute triggers are mostly driven by applying shearing and mechanical forces on the abdomen, and sometimes by rapid decompression of the uterine cavity after vaginal delivery of a first twin or amniotomy.³

Risk factors

Many factors can contribute to the agitation of placental abruption:³

• Chronic and gestational hypertension
• Pregestational and gestational diabetes
• Preeclampsia and eclampsia
• Polyhydramnios and oligohydramnios
• Premature rupture of membranes
• Chorioamnionitis
• Multiple pregnancies
• Thrombophilia
• Genetic risk factors
• Hyperhomocysteinemia
• Alcohol and drug use
• Smoking during pregnancy
• Infertility
• Iron deficiency anaemia and folic acid (folate) deficiency
• Depression, anxiety, and anger
• Advanced maternal age (≥35)
• Black race

Symptoms and outcomes: Maternal symptoms and outcomes:⁴

• Vaginal bleeding
• Abdominal pain
• Contractions
• Foetal distress
• Hypertensive disorders of pregnancy
• Gestational diabetes
• Pulmonary edema
• Placenta previa
• Hysterectomy because of severe blood loss
• Venous thromboembolism
• Diffuse intravascular coagulation (DIC)
• Sepsis and acute kidney injury
• Postpartum haemorrhage

Neonatal outcomes include: 

• Asphyxia
• Preterm birth
• Acidosisevere respiratory disorder
• Encephalopathy
• Cerebral palsy
• And foetal death⁴

Diagnosis

Four grades of placental abruption have been described to diagnose the stage of it:⁵

• Grade 0: It’s asymptomatic with a small retroplacental clot
• Grade 1: Placental abruption is found in about 40% of cases with vaginal bleeding, uterine irritability, tenderness, and no signs of maternal or foetal distress
• Grade 2: Placental abruption is found in approximately 45% of cases with vaginal bleeding, uterine contractions, no signs of maternal shock, and the presence of signs of foetal distress
• Grade 3: Placental abruption is found in about 15% of cases with severe present or concealed bleeding, uterine hypertonus, extremely tender uterine, persistent abdominal pain, maternal shock, maternal coagulopathy, and foetal distress or death

The bleeding can be in different areas; it can be retroplacental (between the myometrium and the placenta), subchorionic (between the myometrium and the placental membranes), or preplacental (between the placenta and amniotic fluid).⁵

A total examination of your placenta is used to confirm placental abruption. In recent abruptions, the specialist can find a crater-like slip covered by dark clotted blood called “delle” on the maternal surface of the placenta. In older abruptions, they find fibrin deposits on the site of the abruption. Sometimes, the bleeding can occur into the uterine myometrium, causing a purple-coloured uterus and leading to a massive postpartum haemorrhage.⁵

When a placental abruption is suspected based on your signs and symptoms, the specialist will perform an ultrasound to visualise a retroplacental or subchorionic hematoma. However, sometimes placental abruption can be diagnosed with an ultrasound, even if it’s asymptomatic. The ultrasonographic manifestation of the abruption depends on the location, size, and age of the hematoma. Acute or small, revealed abruptions are difficult to detect by ultrasound, while concealed haemorrhage might be easier to see. Ultrasound diagnosis abruption correctly only in 15-25% of cases, regardless of the improvements that have been made to the sonographic equipment. On the other hand, the positive predictive value for abruptions increases to 88% when a clot is seen by ultrasound.⁵

When the case of placental abruption is severe, the foetus presents with heart rate abnormalities. There are a lot of foetal cardiotocographic (CTG) patterns that have been associated with placental abruption and foetal distress, such as repetitive late or variable decelerations, decreased beat-to-beat variability, bradycardia, or sinusoidal foetal heart rate patterns. In this case, an emergent action is needed to save the fetus.⁵

Treatment and management

The management of placental abruption depends on the presentation, the gestational age, and the maternal and foetal status. In case of severe abruption with foetal death and the mother is stable regardless of gestational age, the patient can have a vaginal delivery as long as the uterus is contracting vigorously. However, the patient must undergo extremely excessive monitoring in addition to taking into account the blood loss that the patient has suffered from. If there are any problems during the vaginal delivery, a caesarean delivery is performed. After the delivery, the patient should be monitored closely in addition to observing the uterus that must remain contracted; sometimes a hysterectomy is necessary. It’s critical to monitor the patient for any signs of preeclampsia because it can be masked, in some cases, due to the hypovolemia that makes the patient’s pressure normal in this situation.⁶

In the case of a near-term or at-term patient with a live foetus, immediate delivery is required. The type of delivery is determined depending on the situation of both the mother and the foetus. The labour should be performed under intensive monitoring, and the heart condition of the foetus should be observed closely.⁶

When the gestational age is between 20 and 34 weeks with a partial placental abruption and the condition of both the mother and the foetus is stable, then the patient must be managed conservatively. It’s critical to be aware that preterm birth is the leading cause of perinatal death in mothers with abruption, and it’s normal to say that those patients need close monitoring as well.⁶

When there is a suspicion of an abruption after an incidental finding on ultrasound, the case should be managed properly by taking a thorough history and physical examination to find out any possible induction. If the abruption was in a term foetus, then delivery is recommended, while in preterm gestations and the foetus condition is stable, conservative management is recommended. When conservative management is applied, the patient must be hospitalised for further evaluation and assessment.⁶

Summary

Pregnant women are prone to various complications during pregnancy, and some of them might be extremely dangerous and could lead to death for both the mother and the foetus. Placental abruption is one of these conditions that could lead to significantly dangerous manifestations. Many causes and risk factors can contribute to this condition, which could be acute or chronic. Numerous outcomes could occur due to this disorder, and it needs emergency management. Its similarity to many other conditions makes it hard to diagnose, and the treatment is decided according to the patient and the foetus' situation.