Chorionic bump

A chorionic bump is a finding that can be uncommonly seen in a first trimester scan (0.7% of pregnancies 1). It may represent a small haematoma 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.

Radiographic features

Ultrasound 
  • irregular, convex soft tissue bulge projecting from the choriodecidual surface into the gestational sac
MRI
  • may show T1 hyperintensity 1

Treatment and prognosis

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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