Placenta previa

Placenta praevia is when the placenta attaches inside the uterus but near or over the cervical opening. Symptoms include vaginal bleeding in the second half of pregnancy. The bleeding is bright red and tends not to be associated with pain. Complications may include placenta accreta, dangerously low blood pressure, or bleeding after delivery. Complications for the baby may include fetal growth restriction. Placenta praevia is when the placenta attaches inside the uterus but near or over the cervical opening. Symptoms include vaginal bleeding in the second half of pregnancy. The bleeding is bright red and tends not to be associated with pain. Complications may include placenta accreta, dangerously low blood pressure, or bleeding after delivery. Complications for the baby may include fetal growth restriction. Risk factors include pregnancy at an older age and smoking as well as prior cesarean section, labor induction, or termination of pregnancy. Diagnosis is by ultrasound. It is classified as a complication of pregnancy. For those who are less than 36 weeks pregnant with only a small amount of bleeding recommendations may include bed rest and avoiding sexual intercourse. For those after 36 weeks of pregnancy or with a significant amount of bleeding, cesarean section is generally recommended. In those less than 36 weeks pregnant, corticosteroids may be given to speed development of the baby's lungs. Cases that occur in early pregnancy may resolve on their own. It affects approximately 0.5% of pregnancies. After four cesarean sections, however, it affects 10% of pregnancies. Rates of disease have increased over the late 20th century and early 21st century. The condition was first described in 1685 by Paul Portal. Women with placenta previa often present with painless, bright red vaginal bleeding. This commonly occurs around 32 weeks of gestation, but can be as early as late mid-trimester. More than half of women affected by placenta praevia (51.6)% have bleeding before delivery. This bleeding often starts mildly and may increase as the area of placental separation increases. Placenta praevia should be suspected if there is bleeding after 24 weeks of gestation. Bleeding after delivery occurs in about 22% of those affected. Women may also present as a case of failure of engagement of fetal head. The exact cause of placenta previa is unknown. It is hypothesized to be related to abnormal vascularisation of the endometrium caused by scarring or atrophy from previous trauma, surgery, or infection. These factors may reduce differential growth of lower segment, resulting in less upward shift in placental position as pregnancy advances.