Late Pregnancy Bleeding.

Late pregnancy bleeding, any vaginal bleeding that occurs after 20 weeks' gestation, can be due to obstetric emergencies or benign etiologies. The amount of blood loss does not always correlate with seriousness of the etiology, and the source of bleeding is often not immediately obvious. Even small amounts of blood loss should be evaluated carefully because this may be the initial symptom of emergent bleeding. Emergent obstetric etiologies include placental abruption, placenta previa, vasa previa, and uterine rupture. Placental abruption rarely presents with the classic triad of vaginal bleeding, pain, and uterine hypertonicity; vaginal bleeding with abnormal fetal heart rate is more common. Placenta previa is usually diagnosed on ultrasonography but can present with intermittent painless vaginal bleeding. A digital cervical examination should be avoided in patients with placenta previa, but a sterile speculum examination and transvaginal ultrasonography are safe regardless of placental location. Vasa previa, the presence of unprotected vessels outside the placenta running through membranes over or near the cervix, can cause rapidly emergent fetal bleeding. Uterine rupture is an immediate threat to the fetus that requires urgent cesarean delivery. Causes of bleeding that are not emergent include bloody show from labor, bleeding ectropion, cervical polyp, cervicitis, and vaginal infections. Performing ultrasonography to locate the placenta is key in making a diagnosis in patients with late pregnancy bleeding. Frequent vital signs, fetal monitoring, and serial laboratory tests will help identify those at high risk for complications.