Chorionic bump in a pregnant patient with a history of infertility

Correspondence to Dr Rita Simões Carvalho, [email protected]

Background  

Chorionic bump is a rare sonographic finding, in the form of an irregular, convex bulge from the choriodecidual surface that protrudes inside the gestational sac in the first trimester.¹

Literature on the chorionic bump is limited, and because of its low prevalence rate (estimated to be between 1.5/1000 to 7/1000 pregnancies),^{1 2} obstetricians may not be familiar with it.

The aetiology remains uncertain but it may represent a haematoma.^{1 2} This can be asymptomatic or be accompanied by symptoms like pelvic pain or vaginal bleeding.³ There was a significant association between the presence of a chorionic bump and the performance of ultrasound examination for bleeding during the first trimester, indirectly supporting the prevailing theory that bumps may represent haematoma.⁴

In some reports, it is associated with a twofold to fourfold increased risk of early miscarriage,^{1–3 5} but its prognosis and the relationship with spontaneous abortion have not been clearly explained.^{2 6}

The chorionic bump arises within the chorion (ie, trophoblast) immediately beneath the chorionic membrane. It is typically located within the chorion frondosum, the thickest part of the developing placenta, around 7–8   weeks’ gestation, once the umbilical cord  can be seen.⁵

Until date, there have been no ultrasound or clinical markers (like size of the bump) that can predict a difference in outcome. The largest bump described was 3.8 cm.² Besides, there has been no difference in pregnancy outcome as a result of location of the bump, that is, under or away from the cord insertion.⁵

Additionally, it appears that the chorionic bump number matters, but not the size. The majority of the pregnancies described had a single bump. When the described pregnancies had more than one bump, the outcome was demise.^{2 3}

The latest described mean gestational age of diagnosis of chorionic bump is around 11 weeks, later than first described by Harris et al.⁴

Wax et al suggest that a sonographically isolated chorionic bump...