Chorionic bump

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 1.

  • irregular, convex soft tissue bulge projecting from the choriodecidual surface into the gestational sac
  • 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 a 62-65% live birth rate (83% if no other abnormalities) 5,7, but some have suggested that the risk may be overestimated 7. There is one case report of an association with neural tube defects (acrania) 6 which could be related to decreased folate levels.

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Article information

rID: 29910
System: Obstetrics
Section: Signs
Synonyms or Alternate Spellings:
  • Chorionic bumps

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