Placenta previa, placenta accreta, and vasa previa are important causes of bleeding in the second half of pregnancy and in labor. Risk factors for placenta previa include prior cesarean delivery, pregnancy termination, intrauterine surgery, smoking, multifetal gestation, increasing parity, and maternal age. The diagnostic modality of choice for placenta previa is transvaginal ultrasonography, and women with a complete placenta previa should be delivered by cesarean. Small studies suggest that, when the placenta to cervical os distance is greater than 2 cm, women may safely have a vaginal delivery. Regional anesthesia for cesarean delivery in women with placenta previa is safe. Delivery should take place at an institution with adequate blood banking facilities. The incidence of placenta accreta is rising, primarily because of the rise in cesarean delivery rates. This condition can be associated with massive blood loss at delivery. Prenatal diagnosis by imaging, followed by planning of peripartum management by a multidisciplinary team, may help reduce morbidity and mortality. Women known to have placenta accreta should be delivered by cesarean, and no attempt should be made to separate the placenta at the time of delivery. The majority of women with significant degrees of placenta accreta will require a hysterectomy. Although successful conservative management has been described, there are currently insufficient data to recommend this approach to management routinely. Vasa previa carries a risk of fetal exsanguination and death when the membranes rupture. The condition can be diagnosed prenatally by ultrasound examination. Good outcomes depend on prenatal diagnosis and cesarean delivery before the membranes rupture.
Good outcomes with vasa previa depend primarily on prenatal diagnosis and cesarean delivery at 35 weeks of gestation or earlier should rupture of membranes, labor, or significant bleeding occur.
Placental abruption complicates about 1% of pregnancies and is a leading cause of vaginal bleeding in the latter half of pregnancy. It is also an important cause of perinatal mortality and morbidity. The maternal effect of abruption depends primarily on its severity, whereas its effect on the fetus is determined both by its severity and the gestational age at which it occurs. Risk factors for abruption include prior abruption, smoking, trauma, cocaine use, multifetal gestation, hypertension, preeclampsia, thrombophilias, advanced maternal age, preterm premature rupture of the membranes, intrauterine infections, and hydramnios. Abruption involving more than 50% of the placenta is frequently associated with fetal death. The diagnosis of abruption is a clinical one, and ultrasonography and the Kleihauer-Betke test are of limited value. The management of abruption should be individualized on a case-by-case basis depending on the severity of the abruption and the gestational age at which it occurs. In cases where fetal demise has occurred, vaginal delivery is preferable. Disseminated intravascular coagulopathy should be managed aggressively. When abruption occurs at or near term and maternal and fetal status are reassuring, conservative management with the goal of vaginal delivery may be reasonable. However, in the presence of fetal or maternal compromise, prompt delivery by cesarean is often indicated. Similarly, abruption at extremely preterm gestations may be managed conservatively in selected stable cases, with close monitoring and rapid delivery should deterioration occur. Most cases of placental abruption cannot be predicted or prevented. However, in some cases, maternal and infant outcomes can be optimized through attention to the risks and benefits of conservative management, ongoing evaluation of fetal and maternal well-being, and through expeditious delivery where appropriate.
Temporal trends in preterm birth varied substantially based on underlying subtype and maternal race. The recent increase in medically indicated preterm birth was associated with a favorable reduction in perinatal mortality.
Postpartum hemorrhage (PPH) is a leading cause of death and morbidity relating to pregnancy. Uterine atony is the leading cause of PPH, and trauma, including iatrogenic trauma, increases the risk for postpartum hemorrhage. Women with PPH in a pregnancy are at increased risk of PPH in a subsequent pregnancy. Awareness of these facts, and anticipation and prevention of uterine atony, as well as avoiding unnecessary cesareans, episiotomies, and other genital tract trauma have the potential to significantly reduce the mortality and morbidity from postpartum hemorrhage. The epidemiology of postpartum hemorrhage, including the incidence and temporal trends as well as the causes and risk factors associated with it are presented.
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