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.
- 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