Bilobed placenta

Last revised by Joshua Yap on 8 May 2023

A bilobed placenta also referred to as bipartite placenta, is a variation in placental morphology and refers to a placenta separated into two near equal-sized lobes. If more than two lobes are present, it is termed a trilobed, four-lobed, and so on. If the second lobe is smaller than the main lobe (with the umbilical cord insertion), then the smaller lobe is termed a succenturiate lobe.

The estimated incidence is at up to ~4% of pregnancies.

It is thought to result from localized placental atrophy as a result of poor decidualisation or vascularization of a part of the uterus (dynamic placentation theory) 5.

May be sonographically seen as two separate placental discs of nearly equal size. The cord usually attaches to a thin connecting rim of chorionic tissue that bridges the two lobes. Less commonly the cord may insert into one of the lobes.

  • it carries an increased incidence of type II vasa previa

  • it may increase the incidence of postpartum hemorrhage due to retained placental tissue

If more than one lobe of the placenta is seen in an antenatal scan consider:

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Cases and figures

  • Figure 1: bilobed placenta
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  • Figure 2: bilobate placenta with velamentous cord insertion
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  • Case 1
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