Obstetrics 7: Bleeding in the Second Half of Pregnancy Portal
The causes of vaginal bleeding in the second half of pregnancy range from normal events (such as bloody show caused by cervical dilation during labor) to life-threatening situations (such as placental abruption, placenta previa, or vasa previa). Placental abruption occurs in 1% to 2% of pregnancies, resulting in fetal mortality 0.2% of the time. Placenta previa occurs once in every 200 pregnancies. Conditions like bloody show are common; other conditions, like vasa previa, are rare. Treat bleeding with a systematic approach.
Placental abruption
Symptoms upon arrival: abdominal
pain, abdominal tenderness, and vaginal bleeding.
Description of pain varies from menstrual-like cramps to severe
abdominal or back pain
Contractions: usually present;
may seem tetanic to palpation
The intrauterine pressure monitor usually reveals high baseline
pressure with frequent low magnitude contractions superimposed.
If the placenta is distant from the cervical os (negating the possibility of placenta previa), placental abruption is indicated by a sonolucent area between the uterine wall and the placenta or within the substance of the placenta. Unfortunately, a diagnosis of placental abruption is often clinical and not always detectable with ultrasound. As many as 20% of women with a clinically significant abruption have a gross coagulopathy.
Much of the management of abruption is based on the presence or absence of a live fetus. Generally, the best management of abruption is delivery of the fetus. Absence of fetal distress does not assure fetal stability. If no signs of fetal distress or active maternal bleeding are present, delay delivery of a very premature fetus. Placental abruption often stimulates uterine contractions, and delaying delivery until the baby is full-term may not be possible. Routine use of intrauterine pressure monitoring is suggested as uterine hypertonicity often precedes fetal distress. There is no time limit for accomplishing vaginal delivery as long as progress is being made and no other contraindications exist. Fetal distress or massive maternal bleeding requires immediate Cesarean section.
Underestimation of blood loss due to partial or total concealment of maternal hemorrhage is common. Blood should be available in large amounts. In grade 3 abruption, the average blood loss is 2500 cc, and there is risk of coagulopathy. Treatment of coagulopathy includes the use of fresh frozen plasma, platelets, and possibly fibrinogen and cryoprecipitate. Normal increases in circulating blood volume that occur during pregnancy may delay vital sign changes such as tachycardia and hypotension and further complicate accurate assessment.
Placental Abruption Classifications
Grade 1: Diagnosed retrospectively (no special management)
Grade 2: Fetus
alive; mother has a tense, tender uterus
- Maternal support
- 2 IV lines with lactated Ringer’s
- Keep urine above 30 cc/hour.
- HCT, platelet count, urinalysis, clot test, PTT, PT, fibrinogen, type and cross 2 to 4 units packed RBCs
- HCT every hour, maintain at > 30%. Clot test every 2 hours (normal clot in 7 to 10 minutes), PT, PTT, fibrin split products, fibrinogen every 2 hours if initial labs are abnormal.
- Intrauterine pressure monitoring
- Early amniotomy
- Consultation—Evaluate transfer appropriateness for the patient.
- Avoid conduction anesthesia (sympathetic tone).
- Fetal support
- Notify neonatal resuscitation team or additional physician(s) to attend any delivery with abruption, whether vaginal or Cesarean section.
- Fetal scalp electrode: monitor for late decelerations, poor variability, sinusoidal pattern, tachycardia, bradycardia
- Immediate Cesarean section for signs of distress, unless delivery is imminent or fetus is too small to survive.
- Post delivery of infant
- Be prepared for postpartum hemorrhage. Remember Couvelaire uterus (extravasation of blood into the uterine musculature).
- Ascertain associated predisposing conditions and advise the patient of risk of reoccurrence.
Grade 3: Dead fetus
- Hct, platelet count, coagulation studies, clot test, urinalysis, type and cross, 6 units packed RBCs on admission, Hct, and clot test every hour. Treat shock with crystalloid and blood as appropriate. Maintain Hct at 30% and urine output at > 30 cc/hour.
- Consider central line and/or Swan-Ganz monitoring as needed.
- Early amniotomy to prevent amniotic fluid embolus. (This recommendation is controversial.)
- Try to deliver vaginally. Use IUPC (intrauterine pressure catheter) if labor is hypotonic and planning augmentation.
- Treat coagulopathy, if a Cesarean section is being considered. (Give fresh frozen plasma and platelets.)
- Weigh the risks and benefits of transfer for each patient and in each setting.
- In vaginal delivery, minimize the trauma (such as episiotomy).
- Indications for Cesarean section: excessive bleeding, failure of labor to progress, other complications of vaginal delivery.
Placenta Previa
Painless bleeding is the hallmark of placenta previa. The
average time of first bleeding is 27 to 32 weeks. Perform no vaginal
exams until the possibility of placenta previa has been eliminated in
all obstetrics patients who are more than 20 weeks and have vaginal
bleeding.
Direct management toward the safety of the mother; however, delay delivery if possible to ensure fetal maturity. Cesarean section has been shown to improve maternal mortality, but prenatal mortality remains high, mostly due to fetal prematurity.
Once fetal lung maturity has been determined or the patient is in labor, proceed with delivery preparation. If delivery is indicated clinically and the exact relationship of the placental edge to the cervix is unclear on ultrasound, prepare the mother for vaginal delivery in the operating room should Cesarean delivery be necessary.
Vasa Previa
Vasa previa is a rare cause of vaginal bleeding and occurs
when a velamentous insertion of the umbilical cord crosses the cervical
os ahead of the fetal presenting part. Abrupt onset of bleeding occurs
with the rupture of membranes. Rapid fetal exsanguination is a
possibility.
The modified apt test may be helpful in the diagnosis of vasa previa. Mix vaginal blood with a small amount of tap water. Centrifuge for a few minutes. Next add 1 cc of 1% sodium hydroxide (NaOH) (0.25 normal) for every 5 cc supernatant and wait 2 minutes. If the color remains pink, the hemoglobin is from the fetus. If the color is yellowish-brown, the hemoglobin is from the mother. Once a diagnosis is made, perform immediate Cesarean section.
Transfer Criteria
For patients with severe third trimester bleeding (especially
associated with prematurity of the fetus), consider transfer to a
tertiary care center. Do not transfer a patient with massive,
uncontrolled hemorrhage. Before transfer, consider clinical
circumstances such as resources available at the local hospital and
referral center, transfer time, and method of transport.
