Latest SMFM Guidelines: Third Trimester Bleeding Between 34w0d and 36w6d Gestation

SUMMARY:

SMFM provides guidance on the management of patients who present with bleeding in the late preterm period (34w0d to 36w6d).  The following are the key highlights and recommendations:

Placenta Previa

• Stable and no other obstetric complications: Deliver between 36w0d to 37w6d (Grade1B)
• Mild late preterm bleeding with 1 or more prior bleeding episodes that occurred <34 weeks of gestation: Consider delivery due to risk of recurrent bleeding
• Mild bleeding 34 to 35 weeks with resolution by time of evaluation: Management is less clear
• Do not perform routine cervical length screening to determine who will bleed in late preterm period as data in limited on appropriate management (Grade 2C)

Placenta Accreta

• Definition: Abnormal trophoblast infiltration beyond the fibrinoid Nitabuch layer
  • Placenta increta: Placenta invades myometrium
  • Placenta percreta: Placenta invades beyond the myometrium
• Incidence: <1% (in absence of placenta previa unless > 5 prior cesareans
• Risk factors
  • Placenta previa and previous cesarean (most common)
  • Uterine surgery | Advanced maternal age | Smoking | Multiparity
• Stable: Deliver between 34 to 37 weeks (Grade 1C)
  • If patient is stable, it is reasonable to briefly delay delivery to coordinate requisite multidisciplinary team
• ACOG/SMFM recommendations (2019)
  • Delivery for suspected accreta, increta or percreta at 34w0d to 35w6d

Vasa Previa

• Definition: Placental implantation that overlies or abuts the internal cervical os
• Presentation: Painless bleeding
• Incidence
  • Seen in 1 to 4% of second trimester ultrasound exams
  • 10 to 20% of previas diagnosed at 20 weeks gestation will remain a previa in the late 3rd trimester
• Stable: Deliver between 34 to 37 weeks (Grade 1C)

Placental Abruption

• Definition: Placental separation, either partial or complete, prior to delivery
• Incidence: 0.5 to 1%
• Classic presentation
  • Abdominal pain and bleeding
  • Nonreassuring fetal heart rate tracing (approximately 60%)
• Risk factors: Hypertension | Smoking | PPROM | Cocaine abuse | Uterine myomas, and previous abruption
• No clinical trials regarding ideal timing for delivery
  • Stable with high clinical index of suspicion: Delivery in late preterm or early term (expert opinion)
  • Diagnosis unclear, minimal bleeding, both mother and fetus stable: Delivery may be delayed with close surveillance and ongoing fetal testing
  • Active bleeding: Delivery as with any other active hemorrhage case

KEY POINTS:

Delivery Considerations

• If patient actively bleeding, delivery is indicated if the following are present
  • Significant vaginal bleeding
  • Abnormal laboratory results including such as acute anemia or coagulopathy
  • Abnormal fetal heart tracing
  • Maternal status unstable
• If actively hemorrhaging, do not delay delivery for purpose of administering antenatal corticosteroids (Grade 1B)
• Do not perform fetal lung maturity testing in late preterm period to guide management if there is an indication for delivery (Grade 1B)
• Administer antenatal corticosteroids if (Grade 1A)
  • Delivery expected within 7 days
  • Gestational age is between 34w0d to 36w6d
  • Antenatal corticosteroids have not previously been administered
• Cesarean section for placenta previa, vasa previa or accreta
  • For other clinical scenarios, vaginal delivery may be appropriate if
    • No contraindication for vaginal delivery
    • Fetal status is stable
  • Small amount of late preterm bleeding that has resolved by the time the patient presents may be treated expectantly if the following conditions met (no evidence-based recommendations currently available)
    • Both mother and fetus stable
    • Absence of active bleeding or contractions
    • Patient lives close to the hospital

Ultrasound Evaluation

• Perform ultrasound exam to evaluate placental location prior to digital vaginal exam
  • Placental previa: Use transvaginal ultrasound
  • Vasa previa: Pulsed-wave Doppler may help identify a fetal arterial vessel (with FH rate) or fetal vessels with venous flow
• Placenta accreta: Ultrasound can be used, but sensitivity (89 to 92%) and specificity (92 to 97%) less than that of placenta previa and vasa previa
• Placental abruption: Use clinical suspicion/judgement to determine management as ultrasound can miss this diagnosis in 20 to 50% of the cases
• MRI in women who are actively bleeding is not recommended

Laboratory Evaluation

• Depends on clinical status and may include
  • CBC and platelets
  • Type and cross
  • Coag studies: PT/PPT/INR/fibrinogen
  • If transfusion likely: BUN, Cr and lytes
• Wall clot test
  • Place blood in plain (red top) tube
  • Normal expectation is clot within 6 min
• Rh negative patient
  • Assess maternal-fetal hemorrhage
    • Quantitative rosette test
    • Qualitative Kleihauer-Betke stain
    • Flow cytometry
  • Administer standard Rh immunoglobulin dose of 300 μg
    • Increase as needed based on quantitative testing

Initial Stabilization for Delivery

• 2 large-bore intravenous lines
• Obtain results from lab testing above, especially blood type
  • O-neg blood may need to be identified and prepared in the interim
• Crossmatch for an initial 2 to 4 U of blood
• Utilize hemorrhage protocol in units where available
• Fetal heart monitoring is indicated

Evidence Grading System

• 1A: Strong recommendation | High-quality evidence
• 1B: Strong recommendation | Moderate-quality evidence
• 2C: Weak recommendation | Low-quality evidence

Learn More – Primary Sources:

Society for Maternal-Fetal Medicine (SMFM) Consult Series #44: management of bleeding in the late preterm period

ACOG SMFM Committee Opinion 831: Medically Indicated Late-Preterm and Early-Term Deliveries