EP21.14: Chorionic bump: a misfortunate encounter?

Abstract

Chorionic bump (CB) is a rare abnormal condition of the gestational sac seen in the first trimester. It was first reported in 2006 as an important finding in early first trimester sonography. CB appears as a bulge from the choriodecidual surface into the gestational sac (GS). It is typically located within the thickest part of the developing placenta, chorion frondosum. Due to its low prevalence rate (1.5/1000 to 7/1000 pregnancies), its etiology and its significance in relation to pregnancy outcome remains unclear. We report a case of a pregnant woman with a history of infertility, diagnosed in the first trimester with a CB. A 30-year-old G1P0 consulted for an abnormal vaginal bleeding. She had a history of infertility of 18 months. The gestational age was 5 weeks. The transvaginal US demonstrated an intrauterine GS with no embryo. On the follow-up US performed 10 days later, a yolk sac was observed with a CRL of 2.3mm without heartbeat, with one convex CB protruding from the choriodecidual surface inside the GS non-vascularised. It was 23 *15mm.It had a hypoechoic centre and echogenic periphery.US performed a week later showed a CRL of 4.4 mm. The CB‘s size became 30.7*25mm.On the next flow-up the diagnosis of a terminated pregnancy was retained. The pathological exam of the abortus showed large areas of hemorrhage. In conclusion, CB is an under-researched phenomenon in early pregnancy ultrasound. Although seen infrequently, CBs have a striking and characteristic appearance, but when seen for the first time they can present a diagnostic dilemma. The most important task for the sonographer is being aware of their typical appearances and correctly differentiating them from an early embryonic demise. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.