Third trimester bleeding

Revision as of 16:15, 19 March 2026 by Danbot (talk | contribs) (Formatting: removed bold)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)

Background

  • Third trimester bleeding (also termed antepartum hemorrhage) refers to vaginal bleeding occurring after 28 weeks gestational age through delivery[1]
  • Complicates 2–5% of all pregnancies[1]
  • Is an obstetric emergency associated with significant maternal and fetal morbidity and mortality[2]
  • The two most common causes — placental abruption and placenta previa — account for approximately half of all cases[2]
  • The remaining cases are attributable to less common etiologies (vasa previa, uterine rupture, cervical pathology) or remain unexplained
  • The physiologic hypervolemia of pregnancy (30–50% increase in blood volume) may mask early signs of hemorrhagic shock, and clinicians should be aware that significant blood loss can occur before vital sign derangements appear[3]

Clinical Features

General

  • Vaginal bleeding — ranges from light spotting to massive hemorrhage; may be bright red, dark, or mixed with amniotic fluid
  • Bleeding may be partially or completely concealed (e.g. in abruption)
  • Abdominal or pelvic pain, uterine tenderness, or contractions may be present depending on etiology
  • Signs of hemodynamic instability (tachycardia, hypotension, pallor, altered mental status) in severe cases
  • Abnormal fetal heart rate patterns

By Etiology

Placental Abruption

  • Most common cause of painful third trimester bleeding
  • Classic triad: vaginal bleeding, abdominal/uterine pain, uterine contractions[4]
  • Uterus often tender and hypertonic ("woody" or "board-like")
  • Concealed hemorrhage may present without vaginal bleeding but with pain, uterine irritability, and fetal distress[4]
  • May be complicated by DIC in ~10% of cases (more common with fetal death)[1]
  • Risk factors: hypertension/preeclampsia, trauma, cocaine use, tobacco use, prior abruption, PPROM, advanced maternal age, multiparity

Placenta Previa

  • Classic presentation is painless, bright red vaginal bleeding
  • May have an initial "sentinel bleed" that is not immediately life-threatening[1]
  • Bleeding may become profuse without warning
  • Uterus is typically soft and non-tender
  • Risk factors: prior cesarean delivery, prior previa, multiparity, advanced maternal age, smoking, IVF, multiple gestation

Vasa Previa

  • Rare (~1 per 2,500 deliveries) but carries very high fetal mortality when undiagnosed[5]
  • Onset of vaginal bleeding typically coincides with rupture of membranes
  • Bleeding is of fetal origin; even small-volume blood loss can cause rapid fetal exsanguination
  • Fetal heart rate tracing may show sinusoidal pattern or acute bradycardia
  • Risk factors: velamentous cord insertion, bilobed/succenturiate placenta, low-lying placenta, IVF, multiple gestation[5]

Uterine Rupture

  • Most commonly occurs in women with prior uterine surgery (especially prior cesarean section) during trial of labor[6]
  • Presentation may include sudden severe abdominal pain, vaginal bleeding, loss of fetal station, cessation of contractions, and maternal hemodynamic instability
  • Fetal bradycardia is often the earliest and most consistent sign[7]
  • Fetal parts may become palpable through the abdomen
  • Risk factors: prior cesarean section (especially classical incision), myomectomy, uterine instrumentation, labor induction/augmentation, grand multiparity

Differential Diagnosis

Evaluation

Workup

  • Primary survey and maternal stabilization
    • ABCs; two large-bore IVs, crystalloid resuscitation[3]
    • Continuous maternal vital sign monitoring
    • Left lateral uterine displacement
  • Laboratory studies
    • CBC (serial hematocrit)
    • Type and crossmatch (or at minimum type and screen)
    • Coagulation panel: PT/INR, PTT, fibrinogen — screen for DIC
      • Fibrinogen < 200 mg/dL is concerning for consumptive coagulopathy
    • Metabolic panel
    • Kleihauer-Betke test — especially if Rh-negative to calculate RhoGAM dosing
  • Fetal assessment
    • Continuous electronic fetal heart rate monitoring and tocometry
    • Category III fetal heart rate tracings (absent variability with recurrent late/variable decelerations, bradycardia, or sinusoidal pattern) warrant emergent delivery
  • Imaging
    • Transabdominal ultrasound to assess:
      • Placental location (rule out previa before any digital vaginal exam)
      • Retroplacental hematoma (though sensitivity for abruption is limited)
      • Fetal presentation, viability, and amniotic fluid volume
    • Transvaginal ultrasound with color Doppler if vasa previa suspected[5]

Diagnosis

  • Placental abruption is primarily a clinical diagnosis; ultrasound has poor sensitivity (25–50%) because acute hemorrhage may be isoechoic to placental tissue[4]
  • Placenta previa is diagnosed on ultrasound (transabdominal or transvaginal)
  • Vasa previa is diagnosed by transvaginal ultrasound with color Doppler demonstrating fetal vessels over the internal os, confirmed with pulse-wave Doppler showing fetal heart rate waveform[5]
  • Uterine rupture is a clinical diagnosis; ultrasound may show free fluid, abnormal fetal lie, or absent myometrium, but operative findings are often required for confirmation[7]
  • Apt test (alkali denaturation test) can distinguish fetal from maternal blood when the source of bleeding is uncertain; fetal hemoglobin (HbF) resists alkali denaturation and remains pink, while adult hemoglobin (HbA) denatures and turns brown

Critical Rule

  • Do NOT perform a digital vaginal examination until placenta previa has been excluded by ultrasound — digital exam in the setting of previa can precipitate catastrophic hemorrhage[1]
  • Sterile speculum exam may be performed to evaluate the cervix and assess the source/quantity of bleeding

Management

  • Resuscitation
    • IV access with two large-bore (16–18 gauge) catheters
    • Aggressive crystalloid resuscitation; initiate massive transfusion protocol if hemodynamically unstable
    • Correct coagulopathy with blood products (pRBCs, FFP, cryoprecipitate, platelets) as indicated
  • Rh immunoglobulin
    • Administer RhoGAM (300 mcg) to all Rh-negative mothers
    • Additional doses guided by Kleihauer-Betke quantification
  • Fetal monitoring
    • Continuous electronic fetal monitoring; ensure immediate operative delivery capability
  • Condition-specific management
    • Placental abruption
      • Mild, with reassuring fetal status and preterm gestation: close inpatient observation, serial labs, consider antenatal corticosteroids if < 37 weeks
      • Moderate-to-severe abruption, maternal instability, or nonreassuring fetal status: emergent delivery[4]
      • If fetal demise has occurred, vaginal delivery is generally preferred to minimize maternal surgical morbidity[1]
      • DIC: correct coagulopathy aggressively; target fibrinogen > 150–200 mg/dL
    • Placenta previa
      • If stable, not actively hemorrhaging, and preterm: inpatient observation, antenatal corticosteroids, plan for cesarean delivery at 36–37 weeks[1]
      • Active hemorrhage or maternal/fetal instability: emergent cesarean delivery
      • Tocolysis may be considered cautiously if preterm with contractions contributing to bleeding[1]
    • Vasa previa
      • Known diagnosis: planned cesarean delivery at 34–37 weeks of gestation[8]
      • Acute bleeding with rupture of fetal vessels: emergent cesarean delivery and preparation for neonatal transfusion
    • Uterine rupture
      • Emergent cesarean delivery/laparotomy[7]
      • Uterine repair versus hysterectomy depending on extent of injury, hemodynamic stability, and future fertility desires
      • Aggressive resuscitation and blood product administration
  • Antenatal corticosteroids
    • Administer betamethasone or dexamethasone for fetal lung maturity if 23–36+6 weeks gestation and delivery is anticipated, but do not delay emergent delivery for steroid administration[9]
  • MgSO4 for neuroprotection
    • Consider magnesium sulfate for fetal neuroprotection if < 32 weeks gestation and delivery is imminent

Disposition

  • All patients with third trimester bleeding require emergent OB consultation
  • Admit for observation at minimum; most patients will require inpatient monitoring
  • Indications for emergent delivery include:
    • Maternal hemodynamic instability despite resuscitation
    • Category III fetal heart rate tracing in a viable fetus
    • Massive hemorrhage
    • Suspected uterine rupture
    • Ruptured vasa previa
  • If at a facility without obstetric/surgical capability, stabilize and arrange emergent transfer
  • Ensure neonatal resuscitation team (NICU) is available or on standby for all deliveries
  • Social work and emotional support services as needed, particularly in cases of fetal demise

See Also

External Links

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Sakornbut E, Leeman L, Fontaine P. Late pregnancy bleeding. Am Fam Physician. 2007;75(8):1199-1206.
  2. ↑ 2.0 2.1 Gandhi M, Guo W. Prompt evaluation and treatment of third-trimester bleeding. Clin Obstet Gynecol. 2020;63(4):751-760. PMID 33332831.
  3. ↑ 3.0 3.1 Muench MV, Canterino JC. Vaginal bleeding in late pregnancy. Emerg Med Clin North Am. 2019;37(2):251-264. PMID 30940370.
  4. ↑ 4.0 4.1 4.2 4.3 Brandt JS, Ananth CV. Placental abruption at near-term and term gestations: pathophysiology, epidemiology, diagnosis, and management. Am J Obstet Gynecol. 2023;228(5S):S1313-S1329. PMID 37164498.
  5. ↑ 5.0 5.1 5.2 5.3 Oyelese Y, Javinani A, Shamshirsaz AA. Vasa previa. Obstet Gynecol. 2023;142(3):503-518. PMID 37590981.
  6. ↑ Tanos V, Toney ZA. Uterine scar rupture – Prediction, prevention, diagnosis, and management. Best Pract Res Clin Obstet Gynaecol. 2019;59:115-131.
  7. ↑ 7.0 7.1 7.2 Patel RM, Kaler M, Al-Soufi S, et al. Diagnosis and management of uterine rupture in the third trimester of pregnancy: a case series and literature review. Cureus. 2023;15(6):e40060. PMID 37431303.
  8. ↑ Society for Maternal-Fetal Medicine (SMFM); Sinkey RG, Odibo AO, Dashe JS. #37: Diagnosis and management of vasa previa. Am J Obstet Gynecol. 2015;213(5):615-619. PMID 26292048.
  9. ↑ Gyamfi-Bannerman C. Society for Maternal-Fetal Medicine (SMFM) Consult Series #44: Management of bleeding in the late preterm period. Am J Obstet Gynecol. 2018;218(1):B2-B8.
Retrieved from "https://www.wikem.org/w/index.php?title=Third_trimester_bleeding&oldid=386258"