Marginal cord insertion (MCI)

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  Umbilical cord inserts within 2 cm of placenta edge

Velamentous cord insertion (VCI)

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  Umbilical cord inserts on membranes

MCI: All branching vessels are on surface of placenta

VCI: Cord inserts on membranes and at variable distance from placental margin

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  VCI vessels often diverge and travel separately beneath membranes toward placenta

  
  
  
  
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    This has been called “mangrove tree” sign

  
  

VCI in lower uterine segment may cause vasa previa

MCI can progress to VCI if placental margin absorbs

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  Reasons for peripheral atrophy include abruption and poor vascularity of placental margin

Submembranous vessels from succenturiate lobe

VCI incidence: 1-2% singleton, 7% dichorionic twins, up to 40% monochorionic twins

VCI associated with ↑ risk for adverse perinatal outcome

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  Submembranous vessels not protected by Wharton jelly and are susceptible to injury

MCI and VCI are associated with fetal growth restriction

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  3rd trimester follow-up growth scan indicated

Document placental cord insertion site in all cases

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  Especially multiple gestations (can see at time of nuchal translucency)

Rule out vasa previa if VCI is in lower uterus

Do not confuse surface fetal vessels for cord insertion

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  See convergence of vessels into true cord insertion