Chorionic bump

Last revised by Khalid Alhusseiny on 24 Sep 2023

Chorionic bump is a finding that can be uncommonly seen in a first-trimester scan. It may represent a small hematoma bulging into the gestational sac or an anembryonic (failed) second pregnancy that is being resorbed. It is also seen in some patients undergoing infertility treatment.

It is an uncommon sign, seen in about 0.7% of pregnancies <10 weeks 1.

A chorionic bump represents an arterial hematoma in the chorionic plate.

  • irregular, convex soft tissue bulge projecting from the choriodecidual surface into the gestational sac

  • isoechoic to chorion

  • avascular on Doppler mapping

  • may show T1 hyperintensity 1

A chorionic bump has been associated with a guarded prognosis for early pregnancy where the rate of miscarriage has been considered twice the normal rate 2.

Studies have suggested 62-65% overall live birth rate (83% if no other abnormalities) 5,7, but some have suggested that the risk may be overestimated 7. All pregnancies with multiple chorionic bumps ended in demise (100%) 5.

There is one case report of an association with neural tube defects (acrania6 which could be related to decreased folate levels.

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