Antepartum hemorrhage (APH) is vaginal bleeding that occurs after the 20th week of pregnancy but before labor begins. This symptom complicates about 2-5% of pregnancies and requires immediate medical evaluation to determine its cause. The bleeding can range from light spotting to a severe hemorrhage, so prompt medical attention is necessary for a proper diagnosis and management plan.
Primary Causes of Bleeding
The most significant causes of antepartum hemorrhage involve the placenta. Placenta previa is a condition where the placenta partially or completely covers the cervix. As the cervix thins and opens later in pregnancy, this can disrupt the placental attachment and cause bleeding that is typically bright red and painless.
Another primary cause is placental abruption, the premature separation of the placenta from the uterine wall. This separation can disrupt the flow of oxygen and nutrients to the fetus and cause significant bleeding. Unlike placenta previa, placental abruption often causes uterine tenderness, contractions, and abdominal or back pain. The bleeding may be visible or concealed behind the placenta.
A less common cause is vasa previa, where fetal blood vessels cross near the internal opening of the uterus, unprotected by the umbilical cord or placental tissue. When the membranes rupture, these vessels can tear, leading to rapid fetal blood loss. While this may not involve heavy maternal bleeding, it is a direct threat to the baby. Other sources of bleeding can include local causes like cervical polyps, but placental issues remain the most frequent reason for significant hemorrhage.
Medical Evaluation and Diagnosis
When a pregnant individual presents with bleeding, a medical evaluation begins with a detailed history. A clinician will ask about the gestational age, the amount and nature of the bleeding, and any associated symptoms like pain or contractions. They will also review the patient’s medical history for conditions that might increase risk, such as hypertension.
An ultrasound examination is the primary diagnostic tool. A transabdominal ultrasound is performed first to determine the location of the placenta and check for evidence of placenta previa. It can also identify large blood clots that might suggest an abruption. A transvaginal ultrasound may follow for a clearer view of the cervix and lower uterus.
Continuous fetal heart rate monitoring is used to assess the baby’s well-being, as the heart rate pattern can indicate if the fetus is in distress. A speculum examination may be performed to visually inspect the cervix and vagina for other sources of bleeding. Digital vaginal exams are avoided until an ultrasound has ruled out placenta previa, as such an exam could provoke severe hemorrhaging.
Management and Treatment Approaches
Management of antepartum hemorrhage is individualized based on the cause of the bleeding, its severity, gestational age, and the stability of the mother and fetus. The goal is to maintain the mother’s hemodynamic stability while monitoring the baby for distress. This often involves establishing intravenous (IV) access for fluids and potential blood transfusions.
For cases where bleeding is minor and both mother and baby are stable, a “watchful waiting” approach may be adopted. This involves hospitalization for close observation, bed rest, and repeated monitoring. If the pregnancy is preterm (before 34 weeks), a course of corticosteroids is often administered to help accelerate the baby’s lung development.
In situations with severe, ongoing bleeding, or if the mother or fetus becomes unstable, active management is necessary. For conditions like a complete placenta previa or a significant placental abruption causing distress, immediate delivery is the safest option. A Cesarean section is required for placenta previa and vasa previa and is also the quickest route for delivery in cases of severe placental abruption.
Impact on Mother and Fetus
For the mother, substantial blood loss can lead to anemia or hypovolemic shock, a life-threatening condition where severe blood loss prevents the heart from pumping enough blood to the body. Blood transfusions are sometimes necessary to replace lost blood volume and prevent these outcomes.
For the fetus, consequences relate to the underlying cause of the bleeding and the timing of delivery. Placental abruption can deprive the fetus of oxygen, leading to fetal distress. The most common fetal complication is premature birth, which brings its own set of risks like low birth weight and respiratory difficulties. In severe instances of placental abruption or a ruptured vasa previa, the risk of fetal death is high if not managed immediately.