Placental abruption

1. History

• Onset and character of bleeding: Quantity, color (typically dark), duration, intermittent vs. continuous; note that bleeding is concealed in ~18% of cases [1]
• Pain: Abdominal pain, back pain, uterine tenderness; ask about sudden onset vs. gradual
• Contractions: Frequency, regularity, and intensity; uterine irritability or hypertonia
• Fetal movement: Decreased or absent fetal movement
• Precipitating events: Trauma (even minor, e.g., MVA, fall), cocaine/methamphetamine use, recent intercourse
• Gestational age and obstetric history: Prior abruption, prior cesarean, preeclampsia history
• Important negatives: Absence of pain (seen in previa), absence of visible bleeding (concealed abruption), no rupture of membranes

2. Alarm Features

• Hemodynamic instability: Tachycardia, hypotension, signs of hemorrhagic shock [1][5]
• Rigid, "board-like" uterus (uterine hypertonia/tetanic contractions)
• Nonreassuring fetal heart rate tracing (late decelerations, bradycardia, sinusoidal pattern)
• Absent fetal heart tones — abruption involving >50% of the placenta is frequently associated with fetal death [3]
• Signs of DIC: Oozing from IV sites, petechiae, mucosal bleeding — DIC occurs in up to 23% of severe (Stage III) abruptions [6-7]
• Couvelaire uterus (uterine apoplexy) — blood infiltrates the myometrium
• Significant hemorrhage can lead to consumptive coagulopathy, renal failure, and maternal death [5][8]

3. Medications

• Relevant contributors: Cocaine, methamphetamines, and other sympathomimetics are strongly associated with abruption [3][9]
• Anticoagulant therapy may worsen hemorrhage in the setting of abruption
• Treatments:
  • Antenatal corticosteroids (betamethasone 12 mg IM × 2 doses, 24 hours apart) between 24–34 weeks if delivery is anticipated; can be considered 34 0/7–36 6/7 weeks if not previously given [1]
  • RhoGAM (Rho(D) immune globulin) for Rh-negative patients, dosed based on Kleihauer-Betke results [1]
  • Oxytocin for labor augmentation if vaginal delivery is planned
  • Blood products (pRBCs, FFP, cryoprecipitate, platelets) for hemorrhage and coagulopathy management [8][10]
• Tocolytics are generally contraindicated in acute abruption; however, emerging data suggest atosiban may have a role in selected cases for fetomaternal resuscitation prior to cesarean [11]

4. Diet

• Not directly applicable in the acute setting
• Long-term: Adequate folate intake and avoidance of alcohol may reduce general placental pathology risk
• Hydration is critical during resuscitation

5. Review of Systems

• OB/GYN: Vaginal bleeding, leaking fluid (PPROM), contractions, fetal movement
• GI: Nausea/vomiting (can accompany severe abruption), abdominal pain
• GU: Hematuria (may indicate renal involvement or urinary source of bleeding)
• Heme: Easy bruising, bleeding from gums or IV sites (DIC)
• Neuro: Headache, visual changes, hyperreflexia (preeclampsia overlap)
• Constitutional: Lightheadedness, syncope, diaphoresis (hemorrhagic shock)

6. Collateral History and Family History

• Prior obstetric history: Previous abruption is the single strongest maternal risk factor (AOR 2.72) [9]
• History of hypertensive disorders in prior pregnancies
• Thrombophilia history (personal or family): Factor V Leiden, antiphospholipid syndrome [3]
• Social context: Tobacco use, substance use (cocaine, marijuana), intimate partner violence/trauma [9]
• Collateral from EMS/bystanders: Mechanism and severity of trauma if applicable

7. Risk Factors

A 2025 meta-analysis of 54 studies (>7.2 million pregnancies) identified 58 independent risk factors across three categories: [9]

• Maternal baseline: Previous abruption (AOR 2.72), maternal age ≥35, smoking, cocaine use, low BMI (<18.5), multiparity ≥3, anemia (Hgb <11), prior cesarean, prior stillbirth, ART/IVF, unmarried status
• Pregnancy complications: Placenta previa (AOR 7.31 — strongest overall), preeclampsia, gestational hypertension, PPROM, polyhydramnios, SGA, antepartum hemorrhage [9]
• Other: Abdominal trauma, multifetal gestation, intrauterine infection, cervical incompetence, uterine malformations [3][12]

8. Differential Diagnosis

Pearl: A normal ultrasound does NOT rule out abruption. Fresh retroplacental clot can be isoechoic with the placenta. [1][8]

9. Past Medical History

• Prior abruption — recurrence risk is 5–17% after one episode, up to 25% after two [3]
• Chronic hypertension or preeclampsia
• Thrombophilias (antiphospholipid syndrome, Factor V Leiden)
• Prior cesarean delivery or uterine surgery
• History of PPROM, preterm delivery, or stillbirth
• Substance use disorders (cocaine, tobacco)

10. Physical Exam

• Vital signs: Tachycardia and hypotension suggest significant hemorrhage (may be masked by physiologic hypervolemia of pregnancy) [1]
• Abdominal exam:
  • Uterine tenderness (often localized over abruption site)
  • Uterine hypertonia — "woody" or "board-like" uterus; high-frequency, low-amplitude contractions
  • Fundal height may be increasing (expanding concealed hemorrhage)
• Sterile speculum exam: Assess volume/source of bleeding; rule out cervical/vaginal lesions. Do NOT perform digital cervical exam until previa is excluded [1]
• Fetal assessment: Continuous electronic fetal monitoring — look for late decelerations, decreased variability, bradycardia, or sinusoidal pattern [1-2]

11. Lab Studies

• CBC with serial hemoglobin/hematocrit (may be initially normal due to hemoconcentration)
• Type and screen / crossmatch — prepare for transfusion
• Coagulation panel: PT, PTT, fibrinogen (most sensitive early marker of DIC; levels <200 mg/dL are concerning in pregnancy, where normal is 300–600 mg/dL), D-dimer, FDP [6][10]
• Comprehensive metabolic panel — assess renal function (BUN/Cr), LFTs (rule out HELLP)
• Kleihauer-Betke test — quantify fetomaternal hemorrhage in Rh-negative patients; also useful for assessing severity [1]
• Blood bank notification — ensure availability of pRBCs, FFP, cryoprecipitate, platelets
• Serial labs are essential: even with normal initial fibrinogen, progressive decline can occur rapidly [10]

12. Imaging

• First-line: Transabdominal ultrasound — assess placental location, retroplacental clot, fetal presentation, amniotic fluid volume [1][15]
  • Sensitivity is only ~57%; a negative ultrasound does NOT exclude abruption [1]
  • Acute clot may be isoechoic with placenta; older clots become more echo-free and easier to detect [8]
  • Sonographic findings (retroplacental, subchorionic, intraplacental hematomas) when present are associated with worse outcomes (aOR 8.79 for preterm birth) [16]
• Transvaginal ultrasound is safe and can be performed to evaluate placental location and cervical length [1]
• MRI: Sensitivity approaches 100% for abruption (vs. 52% for ultrasound in one study); consider when US is negative but clinical suspicion remains high and diagnosis would change management [17]
• Imaging should never delay delivery in an unstable patient

13. Special Tests

• Continuous electronic fetal monitoring (EFM): Most important real-time assessment tool; abnormal FHR tracing is the most common finding combined with bleeding (39% of cases) [1]
• Kleihauer-Betke test: Quantifies fetal cells in maternal circulation; guides RhoGAM dosing
• Bedside clot test (Lee-White): If coagulation studies are delayed, draw 5 mL of blood in a red-top tube — failure to clot within 6 minutes or clot dissolution suggests DIC
• DIC scoring systems (e.g., JSOG DIC score) — elevated scores on admission predict need for transfusion [10]
• Staging system (per emergency obstetric care guidelines): [6]
  • Stage 0: Asymptomatic (diagnosed retrospectively)
  • Stage I: Vaginal bleeding + abdominal pain, no shock or fetal distress
  • Stage II: Vaginal bleeding ± maternal shock absent, fetal distress present
  • Stage III: Maternal shock, intrauterine fetal demise, coagulopathy (~30%)

14. ECG

• Not a primary diagnostic tool for abruption
• Indications: Obtain ECG if maternal tachycardia, chest pain, or hemodynamic instability to rule out cardiomyopathy, amniotic fluid embolism, or myocardial ischemia from severe hemorrhage
• Sinus tachycardia is the most common finding in hemorrhagic shock
• ST changes may occur with severe anemia/hypovolemia

15. Assessment

Placental abruption is a clinical diagnosis characterized by vaginal bleeding, abdominal pain, uterine hypertonia, and fetal distress — though the classic triad occurs in only ~10% of cases. [1] Severity ranges from mild (incidental finding) to catastrophic (maternal DIC, fetal death). Two-thirds of abruption cases are classified as severe when accounting for maternal, fetal, and neonatal complications. [18]

16. Treatment Plan

17. Disposition

• Admit all patients with suspected or confirmed abruption for continuous monitoring [1]
• ICU/L&D admission for hemodynamic instability, active hemorrhage, DIC, or nonreassuring fetal status
• Transfer to a facility with massive transfusion capability, NICU, and surgical capacity if not available [1]
• Observation (minimum 4 hours) after minor trauma in pregnancy; if no uterine hyperactivity or fetal distress, may consider discharge with close follow-up [1]
• OB/MFM consultation is mandatory for all cases
• Neonatology should be notified for preterm gestations

18. Follow Up / Return Precautions

• If managed expectantly (mild, preterm, stable): Serial ultrasounds, twice-weekly NST/BPP, serial growth scans, serial labs (CBC, coagulation)
• Recurrence counseling: Risk of recurrence in subsequent pregnancies is 5–17% after one episode [3]
• Return precautions: Any vaginal bleeding, abdominal pain, decreased fetal movement, contractions, leaking fluid, lightheadedness, or syncope warrants immediate evaluation
• Postpartum: Monitor for delayed postpartum hemorrhage, anemia, renal function; pathology review of placenta for confirmation
• Future pregnancy planning: Smoking cessation, substance use treatment, blood pressure optimization, early prenatal care, and consideration of low-dose aspirin if preeclampsia risk factors are present [9]