Placental Abruption



Placental Abruption


Yinka Oyelese

Cande V. Ananth

Anthony M. Vintzileos



Introduction

In normal pregnancy, the placenta separates from the wall of the uterus after delivery of the baby. In the setting of abruption, the placenta separates from the uterine wall prior to delivery of the baby.1,2 This deprives the fetus of oxygen and nutrients and may lead to death or serious morbidity of the baby and the mother. Placental abruption is an important cause of bleeding in the second half of pregnancy and is associated with greatly increased risks of stillbirth, neonatal death, preterm delivery, and long-term neurodevelopmental disability.1,2,3,4,5,6,7,8 In addition, abruption carries increased risks for maternal hemorrhage, hypovolemia, coagulopathy, cesarean delivery, intensive care unit admissions, and even maternal death.1,2,3,4,5,6,7,8 Emerging data suggest that women with abruption suffer from increased risk of premature death and substantial morbidity from cardiovascular and cerebrovascular complications later in life.9,10



Clinical Significance

Abruption may vary widely in degree and severity and on its impact on the mother and fetus. The effects of abruption depend primarily on the extent of placental separation, the rapidity at which it separates, and the gestational age at which it occurs.1,11,12 Ananth and colleagues13 carried out a retrospective cohort analysis of 27,796,465 singleton births in the United States between 2006 and 2012 and recommended using at least one of several adverse maternal, fetal, and neonatal outcomes to define severe placental abruption: disseminated intravascular coagulopathy (DIC), hypovolemic shock, blood transfusion, hysterectomy, renal failure, and in-hospital death as criteria for the mother and nonreassuring fetal status, intrauterine growth restriction, fetal death, neonatal death, preterm delivery, or small-for-gestational age as criteria for the fetus and neonate. Any cases where none of these outcomes were present were considered “mild” abruption. They found that two-thirds of cases of all abruptions were classified as “severe” and that the rate of serious maternal medical conditions was 141.7 per 10,000 severe abruption cases, compared with 15.4 per 10,000 pregnancies without abruption.13


Incidence

A US national population-based study between 2006 and 2012 reported an overall prevalence of abruption of 9.6 per 1000 births.13 A population-based study from Finland for 1980 to 2005 found an overall incidence of placental abruption of 3.95/1000 (0.4%) births.14 In twin pregnancies, the rate is approximately double as compared to the rate in singletons.15 The exact incidence will vary in different populations due to heterogeneity in demographics and risk factors.15,16

Several factors may affect the reported incidence of the condition. These include the prevalence of different risk factors for abruption in the studied populations (discussed later), as well as the degree of ascertainment of the diagnosis. The observed incidence of abruption has increased for
several years in the United States and Canada.16 Conversely, studies from Scandinavia have found a decreasing rate of placental abruption.14 A retrospective national cohort study from the Netherlands reported on 1,570,635 women and found that 3496 (0.22%) of them experienced a placental abruption.17 A comparison of abruption rates in seven developed countries (the United States, Canada, Finland, Norway, Sweden, Denmark, and Spain) showed differing rates of abruption, ranging from 3 to 10 per 1000 births.16 After 2000, abruption rates have declined in most of the studied Western countries, whereas rates in the United States rose until 2000 and since then have plateaued. The temporal trends in risk factors, such as the declining prevalence of smoking, may play an important role in the decreasing incidence of abruption.


Risk Factors

Several risk factors for placental abruption have been identified. These include chronic hypertension, preeclampsia, smoking, cocaine use, abdominal trauma, polyhydramnios, oligohydramnios, extremes of maternal age, intrauterine infection, and preterm premature rupture of the membranes.1,2,18,19,20 There is a dose-dependent increased risk of abruption in smokers.2 Other risk factors include congenital uterine/Müllerian anomalies and uterine fibroids.21,22 Vigorous physical exertion has also been linked to an increased risk for abruption.23

The strongest risk factor for placental abruption is a history of abruption in a prior pregnancy.17 Although some studies have found a relationship between inherited thrombophilias and placental abruption, most recent studies and recommendations fail to find such an association.24



Clinical Presentation

Placental abruption typically presents with vaginal bleeding, abdominal pain, contractions, and fetal distress1,3,13,35; however, not all of these symptoms have to be present to make a diagnosis.1 For example, abruption may present with fetal death alone. In addition, abruption may present acutely, with massive vaginal bleeding, severe abdominal pain and contractions, and fetal distress or even death but may also present with minimal vaginal spotting, maternal abdominal discomfort, threatened preterm labor, or even backache.1


Clinical Assessment

The diagnosis of placental abruption is classically based on a presentation of vaginal bleeding in the second half of pregnancy, often with abdominal pain, uterine tenderness, tetanic contractions, and, frequently, fetal distress, or even fetal death.1 When all these signs are present, the diagnosis of abruption is fairly straightforward. Arriving at a diagnosis when some of these signs or symptoms are absent may be more challenging. It is important to realize that not all these findings are present in a significant proportion of cases of abruption, and, as such, making the diagnosis depends on a high degree of suspicion. Making a prompt diagnosis of abruption may lead to timely institution of appropriate treatment, prevent fetal death or severe morbidity, and avoid major morbidity to the mother.

The differential diagnosis includes other causes of bleeding in pregnancy: placenta previa; bleeding from cervical conditions, such as cervicitis,
ectropion, and varices; and preterm labor. An ultrasound examination is useful in distinguishing between abruption and placenta previa. The sensitivity of transvaginal ultrasound for the diagnosis of placenta previa approaches 100%.36 The finding of a placenta covering or close to the internal cervical os makes abruption unlikely. However, a clot/hematoma arising from an abruption that overlies the internal os may be mistaken for a placenta previa. When ultrasound examination shows evidence of abruption, it has an extremely high positive predictive value.37 Conversely, a normal appearing placenta on ultrasound does not preclude abruption (see later for detailed discussion).1,37

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Jun 19, 2022 | Posted by in OBSTETRICS | Comments Off on Placental Abruption
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