ISUOG Recommendations: Fetal Ultrasound Follow-Up for Women with Established Preeclampsia

SUMMARY:

The ISUOG Clinical Standards Committee has released practice guidelines reviewing the latest evidence and provides recommendations regarding the role of ultrasound in follow-up for women diagnosed with preeclampsia.

KEY POINTS:

  • Close fetal surveillance is warranted as deteriorating fetal status may be an indication for earlier delivery
  • Sonographic follow up of PE should include
    • Fetal growth
    • Biophysical profile
    • Fetal Doppler assessments
  • Frequency and impact of sonographic follow up has yet to be determined by large-scale clinical trials

Role of B-mode Ultrasound

Ultrasound assessment should include

  • Fetal growth
    • Rule out impaired growth
  • Biophysical profile
    • BPP of >8: Normal – manifestation of fetal wellbeing
    • BPP of 6: Inconclusive – repeat test
    • BPP of ≤4: Non-reassuring – consider delivery
  • Amniotic fluid volume
    • Ensure presence of MVP >2 cm and/or AFI >5 cm
    • Evidence that MVP may result in fewer interventions (see ‘Related ObG Topics’ below)
  • Placentation
    • Thickness | Echogenicity | Uteroplacental interface
    • Severe PE may be associated with
      • Placental edema and diffuse echogenicity due to edema
      • Thick placenta and reduced vascularization
      • Cystic regions (infarctions/ hematomas)
    • Abruption (poor sensitivity with 50 to 75% missed on ultrasound
      • Hematoma (preplacental and retroperitoneal) | Subchorionic and marginal blood | Increased placental thickness and echogenicity

Role of Doppler Studies

  • 4 major Doppler exams
    • Umbilical artery (UA)
    • Fetal middle cerebral artery (MCA)
    • Fetal ductus venosus
    • Uterine arteries

Especially in the presence of maternal headache, abdominal pain, bleeding and/or reduced fetal movements consider

  • *UA
    • absent or reversed end-diastolic flow is strongly associated with poor perinatal outcomes
    • Increased resistance in the uterine arteries is not a useful indicator for timing of delivery
  • *Fetal MCA PI
    • Reduced MCA-PI <10th percentile (cephalization) may precede abnormal UA indices, and warrants close fetal surveillance
  • *Cerebroplacental ratio (CPR)
    • CPR: MCA PI / UA PI
    • CPR<10th percentile may represent hemodynamic redistribution
    • Warrants close fetal surveillance
  • Fetal ductus venosus
    • Unlike the above 3 indices (marked with *), ductus venosus is not included in ultrasound recommendation list (‘Good Practice Points’) for preeclampsia follow up
    • However, the guideline does point out that a reversed a-wave is strongly association with fetal cardiac deterioration

Note: ISUOG states that the above tests should also “be considered for women admitted for PE or with suspected PE, as well as for those with severe PE or HELLP syndrome” as a ‘Good Practice Point’.

Impact of Medications on Ultrasound Indices

  • Antihypertensives
    • Not associated with changes in maternal and fetal Doppler indices
  • Antenatal steroids
    • Associated with a transient decrease in vascular resistance in the UA and ductus venosus
  • Magnesium sulfate
    • Unclear

Learn More – Primary Sources:

ISUOG Practice Guidelines: role of ultrasound in screening for and follow up of pre-eclampsia