Placental abruption

Template:Distinguish Template:Infobox medical condition (new) Placental abruption is when the placenta separates early from the uterus, in other words separates before childbirth.<ref name=Tik2011>Template:Cite journal</ref> It occurs most commonly around 25 weeks of pregnancy.<ref name=Tik2011/> Symptoms may include vaginal bleeding, lower abdominal pain, and dangerously low blood pressure.<ref name=Merck2017/> Complications for the mother can include disseminated intravascular coagulopathy and kidney failure.<ref name=Tik2011/> Complications for the baby can include fetal distress, low birthweight, preterm delivery, and stillbirth.<ref name=Tik2011/><ref name=Sax2014>Template:Cite book</ref>

The cause of placental abruption is not entirely clear.<ref name=Tik2011/> Risk factors include smoking, pre-eclampsia, prior abruption (most important and predictive risk factor), trauma during pregnancy, cocaine use, and previous cesarean section.<ref name=Tik2011/><ref name=Merck2017/> Diagnosis is based on symptoms and supported by ultrasound.<ref name=Merck2017>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> It is classified as a complication of pregnancy.<ref name=Merck2017/>

For small abruption, bed rest may be recommended, while for more significant abruptions or those that occur near term, delivery may be recommended.<ref name=Merck2017/><ref>Template:Cite book</ref> If everything is stable, vaginal delivery may be tried, otherwise cesarean section is recommended.<ref name=Merck2017/> In those less than 36 weeks pregnant, corticosteroids may be given to speed development of the baby's lungs.<ref name=Merck2017/> Treatment may require blood transfusion or emergency hysterectomy.<ref name=Tik2011/>

Placental abruption occurs in about 1 in 200 pregnancies.<ref name="Shef2014">Template:Cite book</ref> Along with placenta previa and uterine rupture it is one of the most common causes of vaginal bleeding in the later part of pregnancy.<ref>Template:Cite journal</ref> Placental abruption is the reason for about 15% of infant deaths around the time of birth.<ref name=Tik2011/> The condition was described at least as early as 1664.<ref>Template:Cite book</ref>

Signs and symptoms

In the early stages of placental abruption, there may be no symptoms.<ref name=Merck2017/> When symptoms develop, they tend to develop suddenly. Common symptoms include:

• sudden-onset abdominal pain<ref name="Shef2014" /><ref name=":1">Template:Cite journal</ref>
• contractions that seem continuous and do not stop<ref name="Shef2014" />
• vaginal bleeding<ref name="Shef2014" /><ref name=":1" />
• enlarged uterus (disproportionate to the gestational age of the fetus)<ref name="Shef2014" />
• decreased fetal movement<ref name="Shef2014" />
• decreased fetal heart rate.<ref name="Shef2014" />

Vaginal bleeding, if it occurs, may be bright red or dark.<ref name=Merck2017/>

A placental abruption caused by arterial bleeding at the center of the placenta leads to sudden development of severe symptoms and life-threatening conditions including fetal heart rate abnormalities, severe maternal hemorrhage, and disseminated intravascular coagulation (DIC). Those abruptions caused by venous bleeding at the periphery of the placenta develop more slowly and cause small amounts of bleeding, intrauterine growth restriction, and oligohydramnios (low levels of amniotic fluid).<ref name=":0" />

Risk factors

• Pre-eclampsia<ref name=":1" /><ref name="patient">{{#invoke:citation/CS1|citation

|CitationClass=web }}</ref>

• Chronic hypertension<ref name=":1" /><ref name="ReferenceA">Template:Cite journal</ref>
• Short umbilical cord<ref>Template:Cite journal</ref>
• Premature rupture of membranes<ref name=":1" />
• Prolonged rupture of membranes (>24 hours).<ref name="ReferenceA" />
• Thrombophilia<ref name="patient" />
• Polyhydramnios<ref name=":1" />
• Multiparity<ref name="patient" />
• Multiple pregnancy<ref name="patient" />
• Maternal age: pregnant women who are younger than 20 or older than 35 are at greater risk

Risk factors for placental abruption include disease, trauma, history, anatomy, and exposure to substances. The risk of placental abruption increases sixfold after severe maternal trauma. Anatomical risk factors include uncommon uterine anatomy (e.g. bicornuate uterus), uterine synechiae, and leiomyoma. Substances that increase risk of placental abruption include cocaine and tobacco when consumed during pregnancy, especially the third trimester. History of placental abruption or previous Caesarian section increases the risk by a factor of 2.3.<ref name="ReferenceA" /><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref name=":0" />

Pathophysiology

File:Gross pathology of placental abruption.jpg

Gross pathology of a uterus which has been opened to show a placental abruption, with a hematoma separating the placenta from the uterus.

In the vast majority of cases, placental abruption is caused by the maternal vessels tearing away from the decidua basalis, not the fetal vessels. The underlying cause is often unknown. A small number of abruptions are caused by trauma that stretches the uterus. Because the placenta is less elastic than the uterus, it tears away when the uterine tissue stretches suddenly. When anatomical risk factors are present, the placenta does not attach in a place that provides adequate support, and it may not develop appropriately or be separated as it grows. Cocaine use during the third trimester has a 10% chance of causing abruption. Though the exact mechanism is not known, cocaine and tobacco cause systemic vasoconstriction, which can severely restrict the placental blood supply (hypoperfusion and ischemia), or otherwise disrupt the vasculature of the placenta, causing tissue necrosis, bleeding, and therefore abruption.<ref name=":0" />

In most cases, placental disease and abnormalities of the spiral arteries develop throughout the pregnancy and lead to necrosis, inflammation, vascular problems, and ultimately, abruption. Because of this, most abruptions are caused by bleeding from the arterial supply, not the venous supply. Production of thrombin via massive bleeding causes the uterus to contract and leads to DIC.<ref name=":0" />

The accumulating blood pushes between the layers of the decidua, pushing the uterine wall and placenta apart. When the placenta is separated, it is unable to exchange waste, nutrients, and oxygen, a necessary function for the fetus's survival. The fetus dies when it no longer receives enough oxygen and nutrients to survive.<ref name=":0" />

Diagnosis

File:Ultrasound Scan ND 370.jpg

Ultrasound showing placental abruption

Placental abruption is suspected when a pregnant mother has sudden localized abdominal pain with or without bleeding. The fundus may be monitored because a rising fundus can indicate bleeding. An ultrasound may be used to rule out placenta praevia but is not diagnostic for abruption.<ref name=":1" /> The diagnosis is one of exclusion, meaning other possible sources of vaginal bleeding or abdominal pain have to be ruled out in order to diagnose placental abruption.<ref name=Shef2014/> Of note, use of magnetic resonance imaging has been found to be highly sensitive in depicting placental abruption, and may be considered if no ultrasound evidence of placental abruption is present, especially if the diagnosis of placental abruption would change management.<ref>Template:Cite journal</ref>

Classification

Based on severity:Template:Cn

• Class 0: Asymptomatic. Diagnosis is made retrospectively by finding an organized blood clot or a depressed area on a delivered placenta.
• Class 1: Mild and represents approximately 48% of all cases. Characteristics include the following:
  • No vaginal bleeding to mild vaginal bleeding
  • Slightly tender uterus
  • Normal maternal blood pressure and heart rate
  • No coagulopathy
  • No fetal distress
• Class 2: Moderate and represents approximately 27% of all cases. Characteristics include the following:
  • No vaginal bleeding to moderate vaginal bleeding
  • Moderate-to-severe uterine tenderness with possible tetanic contractions
  • Maternal tachycardia with orthostatic changes in blood pressure and heart rate
  • Fetal distress
  • Hypofibrinogenemia (i.e., 50–250 mg/dL)
• Class 3: Severe and represents approximately 24% of all cases. Characteristics include the following:
  • No vaginal bleeding to heavy vaginal bleeding
  • Very painful tetanic uterus
  • Maternal shock
  • Hypofibrinogenemia (i.e., <150 mg/dL)
  • Coagulopathy
  • Fetal death

Prevention

Although the risk of placental abruption cannot be eliminated, it can be reduced. Avoiding tobacco, alcohol and cocaine during pregnancy decreases the risk. Staying away from activities which have a high risk of physical trauma is also important. Women who have high blood pressure or who have had a previous placental abruption and want to conceive must be closely supervised by a doctor.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

The risk of placental abruption can be reduced by maintaining a good diet including taking folate, regular sleep patterns and correction of pregnancy-induced hypertension.Template:Cn

Use of aspirin before 16 weeks of pregnancy to prevent pre-eclampsia also appears effective at preventing placental abruption.<ref>Template:Cite journal</ref>

Management

Treatment depends on the amount of blood loss and the status of the fetus.<ref>Template:Citation</ref> If the fetus is less than 36 weeks, and neither mother or fetus are in any distress, then they may simply be monitored in hospital until a change in condition or fetal maturity whichever comes first.Template:Cn

Immediate delivery of the fetus may be indicated if the fetus is mature or if the fetus or mother is in distress. Blood volume replacement to maintain blood pressure and blood plasma replacement to maintain fibrinogen levels may be needed. Vaginal birth is usually preferred over Caesarean section unless there is fetal distress. Caesarean section carries an increased risk in cases of disseminated intravascular coagulation. The mother should be monitored for 7 days for postpartum hemorrhage. Excessive bleeding from uterus may necessitate hysterectomy. The mother may be given Rhogam if she is Rh negative.Template:Cn

Prognosis

The prognosis of this complication depends on whether treatment is received by the patient, on the quality of treatment, and on the severity of the abruption. Outcomes for the baby also depend on the gestational age.<ref name=Shef2014/>

In the Western world, maternal deaths due to placental abruption are rare. The fetal prognosis is worse than the maternal prognosis; approximately 12% of fetuses affected by placental abruption die. 77% of fetuses that die from placental abruption die before birth; the remainder die due to complications of preterm birth.<ref name=":0">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Without any form of medical intervention, as often happens in many parts of the world, placental abruption has a high maternal mortality rate.Template:Cn

Mother

• A large loss of blood may require a blood transfusion.<ref name=Tik2011/>
• If the mother's blood loss cannot be controlled, an emergency hysterectomy may become necessary.<ref name=Tik2011/>
• The uterus may not contract properly after delivery so the mother may need medication to help her uterus contract.
• The mother may develop a blood clotting disorder, disseminated intravascular coagulation.<ref name=Tik2011/>
• A severe case of shock may affect other organs, such as the liver, kidney, and pituitary gland. Diffuse cortical necrosis in the kidney is a serious and often fatal complication.<ref name=Tik2011/>
• Placental abruption may cause bleeding through the uterine muscle and into the mother's abdominal cavity, a condition called Couvelaire uterus.<ref>Template:Cite journal</ref>
• Maternal death.<ref name=Tik2011/>

Baby

• The baby may be born at a low birthweight.<ref name=Tik2011/>
• Preterm delivery (prior to 37 weeks gestation).<ref name=Tik2011/>
• The baby may be deprived of oxygen and thus develop asphyxia.<ref name=Tik2011/>
• Placental abruption may also result in death of the baby, or stillbirth.<ref name=Tik2011/>
• The newborn infant may have learning issues at later development stages, often requiring professional pedagogical aid.

Epidemiology

Placental abruption occurs in approximately 0.2–1% of all pregnancies.<ref name=":1" /> Though different causes change when abruption is most likely to occur, the majority of placental abruptions occur before 37 weeks gestation, and 12–14% occur before 32 weeks gestation.<ref name=":1" /><ref name=":0" />