Antepartum Hemorrhage

Learning objectives

After completing this chapter, you should be able to differentiate placenta previa, placental abruption, vasa previa, uterine rupture, and placenta accreta spectrum; recognize concealed blood loss; identify findings that make digital vaginal examination unsafe; explain maternal and fetal consequences; interpret uterine tone and fetal-heart changes; anticipate coagulopathy; and choose when transport should continue, divert, or transition to immediate delivery capability.

Opening transport scenario

A 38-year-old patient at 35 weeks with two prior cesarean births develops bright-red vaginal bleeding. She initially has no pain and a soft uterus. Ultrasound records indicate an anterior low-lying placenta. During transport she develops abdominal pain, a firm tender uterus, tachycardia, and recurrent fetal late decelerations. The team must avoid assuming that one diagnosis explains every change and must recognize that previa, accreta, abruption, and uterine rupture can overlap in a high-risk patient.

1. First actions for bleeding after 20 weeks

1. Assess airway, ventilation, circulation, mental status, perfusion, and shock.
2. Position to avoid aortocaval compression and provide oxygen for maternal hypoxemia.
3. Quantify visible bleeding without delaying resuscitation; inspect beneath the patient.
4. Obtain large-bore vascular access and prepare blood products early when bleeding is significant.
5. Assess uterine tone, tenderness, contractions, pain, membrane status, and fetal heart rate.
6. Review placental location, prior cesarean or uterine surgery, trauma, hypertension, and previous accreta or abruption.
7. Avoid digital vaginal examination until placenta previa has been excluded by an appropriate clinician.
8. Identify the closest facility capable of immediate cesarean delivery, massive transfusion, anesthesia, and neonatal resuscitation.

2. Placenta previa

Placenta previa occurs when placental tissue overlies or approaches the internal cervical os. Classic bleeding is painless, bright red, and associated with a soft, nontender uterus, but real presentations may vary. Contractions can coexist, and substantial hemorrhage may develop without warning.

• Do not perform a digital vaginal examination when previa is possible.
• Review the most recent ultrasound because placental location can change as pregnancy progresses.
• Prepare for recurrent or sudden severe bleeding even if the first episode stops.
• Prior cesarean birth plus placenta previa markedly increases placenta accreta-spectrum risk.
• Choose a destination with obstetric surgery and blood-bank capability.

3. Placental abruption

Abruption is premature separation of the placenta. Bleeding may be external, concealed behind the placenta, or both. Typical findings include sudden abdominal or back pain, uterine tenderness, hypertonicity, frequent contractions, maternal shock, and fetal distress. The quantity of vaginal blood does not reliably indicate severity.

Ultrasound may support the diagnosis but is not sufficiently sensitive to exclude abruption. A reassuring image must not override the clinical pattern.

4. Vasa previa

Vasa previa occurs when unprotected fetal vessels cross or lie near the cervical os. Vessel rupture—often with membrane rupture—can cause rapid fetal exsanguination while maternal vital signs remain normal. The classic emergency pattern is vaginal bleeding after rupture of membranes with abrupt fetal bradycardia or a sinusoidal pattern.

• Treat the fetal-heart change as a surgical emergency.
• Do not assume maternal stability means the bleeding is minor.
• Notify the receiving team that the blood may be fetal and neonatal transfusion may be required.
• Prioritize immediate cesarean-capable destination rather than prolonged transfer to a more distant center.

5. Uterine rupture

Uterine rupture is disruption of the uterine wall and is most often associated with a previous uterine scar, though it can occur in an unscarred uterus. Fetal bradycardia is often the earliest and most consistent finding. Other clues include sudden pain, loss of fetal station, abnormal fetal parts on abdominal examination, cessation or change in contractions, vaginal bleeding, maternal shock, or fetal movement outside the uterine contour.

Definitive treatment is immediate surgery. Continue maternal resuscitation, activate blood products, and use the closest appropriate surgical obstetric destination.

6. Placenta accreta spectrum

Placenta accreta spectrum describes abnormal placental attachment and invasion into or through the uterine wall. Risk is highest with placenta previa and previous cesarean delivery. Bleeding can become catastrophic when placental separation is attempted. Known or suspected cases should be managed at a center with multidisciplinary obstetric surgery, anesthesia, massive transfusion, critical care, and often interventional radiology.

Do not manually pull on a placenta that does not separate normally. During postpartum transport, clarify whether the placenta remains in situ, whether accreta is suspected, and what surgical plan has been established.

7. Maternal shock and coagulopathy

Pregnancy may delay obvious hypotension. Use trend, shock index, mental status, skin perfusion, pulse pressure, EtCO₂ when appropriate, urine output, fetal status, hemoglobin trend, fibrinogen, platelets, and coagulation. Abruption is particularly associated with rapid fibrinogen consumption and disseminated intravascular coagulation.

• Activate blood products early rather than relying on repeated crystalloid.
• Prevent hypothermia and monitor ionized calcium during transfusion.
• Recognize that a single normal hemoglobin does not exclude acute blood loss.
• Prepare for postpartum hemorrhage after delivery.

8. Focused transport examination

9. Continue, divert, or prepare for delivery

• Continue: stable maternal and fetal status, controlled bleeding, appropriate monitoring, and a clearly superior destination within a safe travel time.
• Divert: worsening shock, persistent or recurrent fetal compromise, rapidly increasing bleeding, suspected rupture, vasa previa, or inadequate reserve for the remaining route.
• Prepare for emergency delivery: imminent vaginal birth when stopping is unavoidable, while recognizing that many hemorrhage diagnoses require operative rather than field delivery.
• Pause departure: when immediate surgery at the sending facility is safer than movement.

10. Evolving case study

Phase 1

The initial painless bright-red bleeding and low-lying placenta suggest previa. Digital examination is avoided, blood is prepared, and the surgical receiving center is activated.

Phase 2

New pain, uterine firmness, and recurrent fetal decelerations raise concern for superimposed abruption or uterine rupture. Visible blood remains modest, but shock index rises and fibrinogen falls.

Phase 3

Fetal bradycardia persists. The original destination is 30 minutes away, while a cesarean-capable obstetric facility with blood products is 7 minutes away. The team diverts and reports possible previa/accreta with acute abruption or rupture.

11. High-yield summary

• Placenta previa classically causes painless bright-red bleeding and makes digital examination unsafe.
• Abruption may be painful, tender, hypertonic, and largely concealed.
• Ultrasound cannot reliably exclude abruption.
• Vasa previa can cause fetal exsanguination with normal maternal vital signs.
• Fetal bradycardia is a common early sign of uterine rupture.
• Prior cesarean plus previa markedly increases accreta-spectrum risk.
• Bleeding amount does not reliably predict severity.
• Destination and diversion decisions must prioritize immediate operative and transfusion capability.

References

1. American College of Obstetricians and Gynecologists. Placenta Previa and Placenta Accreta Spectrum.
2. Society for Maternal-Fetal Medicine. Consult Series #44: Management of bleeding in the late preterm period. Reaffirmed 2024.
3. Society for Maternal-Fetal Medicine. Consult Series #37: Diagnosis and management of vasa previa. Reaffirmed 2024.
4. American College of Obstetricians and Gynecologists. Guidance on placental abruption and uterine rupture.
5. International Board of Specialty Certification. Maternal Fetal Transport Microcredential Candidate Handbook. Updated April 2026.