Obstetrics and Gynecology/Hemorrhage in the Late Third Trimester and Parturition

Epidemiology 5% of pregnancies are affected by hemorrhage, and 10% of maternal deaths in the developed world are the result of bleeding. Etiology Abruption of the placenta (prematue separation of the placenta from the uterine wall) Complicates 1% of pregnancies and is the major cause of antepartum bleeding. These are very difficult to identify and diagnose. May be caused by trauma, cocaine use, and sudden uterine decompression. Smoking, hypertension, and history of previous placental abruption increase the risk of future abruption. Placenta previa Placenta covering or in close proximity to the internal cervical canal. Placenta previa is responsible for approximately 20% of bleeding in late pregnancy; less than abruption of the placenta. 0.5% of pregnancies will be affected at term. Some may start as previa but migrate away from the cervix with pregnancy. Risk increases with previous placenta previa, cesarian section, advancing maternal age, multiparity, smoking, and prior abortions. Uterine rupture Vasa previa Lower genital tract bleeding from laceration, iatrogenesis, cervical cancer. Gastointestinal or urinary tract bleeding confused with genital bleeding. Placental morphology may facilitate bleeding. Pathophysiology Placental abruption: hemorrhage into the basal decidua of the placenta, coupled with uterine contractions leads to placental separation. Further hemorrhage exacerbates prostaglandin formation and separation of the placenta. Placenta previa: bleeding can create abruption. Clinical Presentation Abruption of the placenta Bleeding Cramps/pain Absent contractions Non-reassuring fetal heart rate Placenta previa Will usually present initially with an asymptomatic bleed that resolves spontaneously. Diagnosis must be made by transvaginal ultrasound. Make sure that it is not vasa previa: test nucleated blood cells with a sodium hydroxide dilution test. Complications Abruption of the placenta Hypovolemia Post-partum pituitary insufficiency (Sheehan's syndrome) ARDS Cardiac arrest Fetal death (11% in developed countries) Prematurity/intrauterine growth retardation Management Abruption of the placenta ABC's, hemodynamic stability Prep for operating room Blood transfusion and or clotting factor replacement Rapid exsanguination indicates cesarian section and hysterectomy; stable bleeding indicates delivery; mild bleeding indicates conservative observation with steroids for fetal lung development. Placenta previa ABC's and hemodynamic stability Cesarian section unless unviable pregnancy There is a risk of fetal hemorrhage and perinatal mortality of >10%. Stable with ongoing bleeding: admission, tocolysis for contractile cessation, and steroids for fetal development Unstable mother or fetus: cesarian section unless nonviable No hemorrhage warrants assessment of fetal lung function