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