Obstetric Topic 32. Placental abruption

I. Definition and Risk Factors

Definition

• Placental abruption / abruptio placentae: premature separation of a normally implanted placenta from the uterine wall before delivery, usually after 20 weeks.
• Main danger: maternal hemorrhage + reduced uteroplacental perfusion → fetal hypoxia/death.

Risk Factors

• Hypertension / preeclampsia.
• Previous abruption.
• Multiple pregnancy or uterine overdistension: polyhydramnios.
• PROM/PPROM.
• Trauma: accident, fall, domestic violence, procedures.
• Smoking, cocaine or other vasoconstrictive drugs.
• Placental ischemic disease / FGR and thrombophilia are additional risks.

II. Types and Pathophysiology

Types

• Revealed hemorrhage: blood dissects downward through cervix → visible vaginal bleeding.
• Concealed hemorrhage: blood trapped behind placenta → little/no vaginal bleeding despite severe shock.
• Partial vs complete abruption: complete separation causes severe fetal compromise/death.
• Acute vs chronic: acute pain/bleeding/fetal distress; chronic/recurrent bleeding may cause FGR or preterm birth.

Pathomechanism

• Rupture of maternal decidual vessels → bleeding into decidua basalis → retroplacental hematoma.
• Placental separation → reduced uteroplacental perfusion → fetal hypoxia, acidosis or death.
• Disrupted placenta releases tissue factor/thromboplastin → consumptive coagulopathy → DIC.
• Couvelaire uterus: blood infiltrates myometrium/serosa → poor uterine contraction and PPH risk.

III. Clinical Features, Diagnosis and Complications

Clinical Features

• Classic triad: painful 3rd-trimester bleeding + tender/rigid uterus + non-reassuring or absent FHR.
• Pain: acute, severe, continuous abdominal or back pain.
• Uterus: tender, hypertonic, "board-like" / rock-hard.
• Bleeding: visible in revealed abruption; absent/minimal in concealed abruption.
• Maternal signs: tachycardia, hypotension, hemorrhagic shock, oliguria, DIC bleeding.

Diagnosis

• Diagnosis is mainly clinical; do not wait for ultrasound if mother/fetus is unstable.
• Physical examination: rock-hard/tender uterus.
• CTG/FHR monitoring: fetal distress or fetal death.
• Labs: Hb/Hct, platelets, blood group/crossmatch, PT/aPTT, fibrinogen, renal function.
• DIC signs: thrombocytopenia, prolonged PT/aPTT, low fibrinogen, increased D-dimer/FDP.
• Ultrasound: may show retroplacental hematoma and helps exclude placenta previa, but normal US does not rule out abruption.

Complications

• Maternal: hemorrhagic shock, DIC, acute renal failure, postpartum hemorrhage, Couvelaire uterus.
• Late maternal: Sheehan syndrome after severe obstetric hemorrhage.
• Fetal/neonatal: hypoxia/asphyxia, preterm birth, FGR in chronic abruption, stillbirth/neonatal death.

IV. Management

Initial Stabilization

1. Call senior obstetric/anesthesia/neonatal team; prepare operating theatre and blood bank.
2. Maternal ABCs: oxygen if needed, left lateral tilt, 2 large-bore IV lines, IV fluids and blood products.
3. Monitor BP, pulse, oxygen saturation, urine output, bleeding, uterine tone and CTG if fetus viable.
4. Repeat labs: CBC, platelets, PT/aPTT, fibrinogen, renal function, crossmatch.
5. Correct coagulopathy: packed RBC, FFP, cryoprecipitate/fibrinogen and platelets according to bleeding/labs.

Delivery Decision

• Maternal instability, major bleeding or DIC: aggressive resuscitation + urgent delivery.
• Alive fetus + non-reassuring fetal heart rate: emergency cesarean unless vaginal birth is imminent.
• Stable mother + stable fetus + mild/preterm abruption: hospital observation, serial labs and fetal monitoring; corticosteroids if preterm delivery risk.
• Stable mother and vaginal delivery expected soon: induction/amniotomy/oxytocin may be used carefully.
• Dead fetus: vaginal delivery/induction preferred if mother is stable; cesarean only for maternal indications.
• Prepare for postpartum hemorrhage after any delivery.