We're heading down the Taco Aisle at Twins R' Us this week as we dive into sIUGR also known as selective intrauterine growth restriction. Join us this week as we discuss the following: 

• Defining sIUGR in monochorionic twins
  • Must meet at least two of the following four criteria
    • Smaller twin must be less than 10th percentile for EFW by ultrasound
    • And/Or the smaller twin’s AC must be less than 10th percentile for gestational age
    • More than 25% difference of smaller twin and the bigger twin EFW
    • UA Doppler of the smaller twin has a pulsatility index greater than 95th percentile for gestational age
• Doppler measurements and why we do them
  • UA Doppler – surrogate marker for placental resistance & placental territory or how much placenta each baby has
    • Pulsatility index = (systolic velocity – diastolic velocity) / mean
    • AEDF – high resistance in the placenta
    • REDF – if the blood ‘bounces’ off the placenta from the UA
• Defining sIUGR in dichorionic twins
  • Must meet at least two of the following three criteria
    • Smaller twin must be less than 10th percentile for EFW by ultrasound
    • More than 25% difference of smaller twin and the bigger twin EFW
    • UA Doppler of the smaller twin has a pulsatility index grea ter than 95th percentile for
• How often sIUGR occurs in monochorionic twins
• The three subtypes of sIUGR described by Dr. Eduard Gratacos & their rate of occurrence
  • Type 1 – positive EDF in smaller twin
    • 29% of sIUGR cases
  • Type 2 – Absent or reversed EDF in smaller twin
    • 22% of sIUGR cases
  • Type 3 – Absent or reversed EDF in smaller twin alternating with positive diastolic flow
    • 49% of sIUGR cases
• The placental vessel anastomoses types & their frequency in each subtype of sIUGR
  • Arterial to arterial (AA)
  • Arterial to venous (AV)
  • Venous to arterial (VA)
  • Venous to venous (VV)
  • ‘Spiders’
• Umbilical artery cord Doppler physiology differences between singleton pregnancies and monochorionic twin pregnancies
• Ductus venosus Doppler as surrogate marker for fetal cardiac function
• Defining a cotyledon
• Outcomes based on sIUGR subtypes
• Typical gestational age at delivery for each subtype
• Management, possible complications & outcomes for each subtype of sIUGR

 

Glossary of Abbreviations 

• sIUGR – selective intrauterine growth restriction
• FGR – fetal growth restriction
• SGA – small for gestation