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
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.
- 1. Harris RD, Couto C, Karpovsky C et-al. The chorionic bump: a first-trimester pregnancy sonographic finding associated with a guarded prognosis. J Ultrasound Med. 2006;25 (6): 757-63. J Ultrasound Med (full text) - Pubmed citation
- 2. Sana Y, Appiah A, Davison A et-al. Clinical significance of first-trimester chorionic bumps: a matched case-control study. Ultrasound Obstet Gynecol. 2013;42 (5): 585-9. doi:10.1002/uog.12528 - Pubmed citation
- 3. Tan S, Ipek A, Akın Sivaslıoğlu A et-al. The chorionic bump: Radiologic and pathologic correlation. J Clin Ultrasound. 2011;39 (1): 35-7. doi:10.1002/jcu.20755 - Pubmed citation
- 4. Northrup BE, Harris RD. The chorionic bump in an ectopic pregnancy. J Clin Ultrasound. 2009;37 (5): 292-4. doi:10.1002/jcu.20544 - Pubmed citation
- 5. Arleo EK, Troiano RN. Chorionic bump on first-trimester sonography: not necessarily a poor prognostic indicator for pregnancy. J Ultrasound Med. 2014;34 (1): 137-42. doi:10.7863/ultra.34.1.137 - Pubmed citation
- 6. Wegrzyn P, Brawura-Biskupski-Samaha R, Borowski D et-al. The chorionic bump associated with acrania-case report. Ginekol. Pol. 2014;84 (12): 1055-8. Pubmed citation
- 7. Arleo EK, Dunning A, Troiano RN. Chorionic Bump in Pregnant Patients and Associated Live Birth Rate: A Systematic Review and Meta-analysis. J Ultrasound Med. 2015;34 (4): 553-7. doi:10.7863/ultra.34.4.553 - Pubmed citation