Snap Shot A 33-year-old G4P3 presents at 29 weeks gestation by dates with painless vaginal bleeding. The bleeding began two hours ago and has delivered a substantial amount of blood with clots. She is having no uterine contractions and the fetal heart rate is 150. Her last pregnancy was delivered by emergency cesarean at 37 weeks due to double-footing breech presentation during labor. Introduction Placenta Abrupto and Placenta Previa are the two most common causes of third trimester bleeding In Placenta Previa, the placenta is implanted over internal cervical os Classified as total partial marginal low lying Incidence is 1/200 Risk factors include prior cesarean sections grand multiparous advanced maternal age Presentation Symptoms painless bright red bleeding at 29-30 weeks of note abruptio is painful bleeding often stops in 1-2 hours with or without uterine contractions usually no fetal distress (vs. vasa previa which normally presents with fetal heart deccelerations due to compression of umbilical vessels) Evaluation Transabdominal ultrasound to look for abnormally positioned placenta Vaginal exam and transvaginal ultrasound are contraindicated due to risk of placental disruption Differential Abruptio placentae Treatment Stablize patient with premature fetus treatment pelvic rest tocolytics (magnesium sulfate) amniocentesis to check fetal lung maturity Proceed with delivery (Caesarean section) if persistant labor blood loss > 500 mL coagulation defects documented fetal lung maturity L:S ratio > 2 > 36 weeks gestation Prognosis, Prevention, and Complications Associated with 2-fold increase in congenital malformations Placenta accreta Vasa previa rupture of fetal vessels that cross the membranes covering the cervix treat with C-section Increases risk of postpartum hemorrhage