Content area
Full Text
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 3.8cm. 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 may significantly increase the likelihood of fetal chromosomal abnormality among pregnancies with increased aneuploidy risk; this can be important for counselling the patient. 7
In spite of the haematoma hypothesis and findings of coagulation issues in some...