The chorionic bump: Etiologic insights from two pathologic pregnancies

New insight on etiology: A chorionic bump with partial mole pregnancy case report from Syria

This case report presents the association of a chorionic bump with a partial mole pregnancy in a 37-year-old G3P2 woman. The differential diagnosis of a partial mole was considered after transvaginal ultrasonography revealed a chorionic bump. Subsequent pathological analysis confirmed the diagnosis. While the etiology of the chorionic bump remains dubious, we hypothesize an alternative explanation for chorionic bump formation based on the presence of three unique pathological features: necrosis, edema, and hemorrhage.

Case report: Chorionic bump detected in the third trimester

A chorionic bump (CB) is a focal irregular bulge in the surrounding choriodecidual due to hematoma. The incidence of CB is between 1.5 and 7 per 1000 pregnancies. The presence of a chorionic bump is associated with a significantly higher risk of adverse perinatal outcomes. CB often decreases in size with time and rarely persists beyond the first trimester. Our case report presents and discusses a chorionic bump diagnosed in the third trimester. To our knowledge, this is the first case of CB to reported in the third trimester.

Chorionic bump at 11 to 13 weeks' gestation: Prevalence and clinical significance

OBJECTIVE

To gather additional data on pregnancy outcome when a chorionic bump is detected at the time of the 11- to 13-week scan.

METHODS

The presence of a chorionic bump was prospectively recorded in a database of women presenting for their first-trimester sonographic screening. Clinically relevant information was obtained by reviewing ultrasound reports and medical records or contacting the referring obstetrician or the parents themselves.

RESULTS

During a 4.5-year study period from June 2014 to December 2018, a chorionic bump was identified in 23 out of 3375 pregnancies, for a prevalence of 1/147 or 0.7%. All women were asymptomatic at the time of evaluation. The chorionic bump was single in 21 (91%) cases, located in the central part of the placenta in 17 (74%) cases, and the median largest diameter was 20 mm (range, 10-43). Although the placenta was low-lying in 14 (61%) cases, all but one patient had a normally located placenta at the midtrimester anatomy scan. With the exception of one pregnancy complicated with trisomy 21, the outcome was universally good.

CONCLUSION

Our experience suggests that a chorionic bump detected during the 11- to 13-week scan is usually a transient, is incidental finding, and probably has no clinical significance.

First-trimester chorionic bump--Association with fetal aneuploidy in a high-risk population

PURPOSE

To determine the relationship between the first-trimester chorionic bump and fetal aneuploidy.

METHODS

This retrospective cohort study included all singleton pregnancies with chromosomal analysis and sonographic examination performed between 5 0/7 and 13 6/7 weeks from January 1, 2010 through August 15, 2015. Interobserver and intraobserver agreement for identifying a chorionic bump was evaluated by the Kappa statistic. Pregnancies with and without a chorionic bump were compared regarding patient characteristics and fetal karyotypes.

RESULTS

Six hundred ninety subjects were included, 16 (2.3%) having a bump. The kappa coefficients for interobserver agreement were 0.88 (95% confidence interval [CI]: 0.71-1.00) and 0.94 (95% CI: 0.82-1.00); those for intraobserver agreement were 0.81 (95% CI: 0.61-1.00) and perfect agreement. One hundred seventeen fetuses (16.9%) were aneuploid, of which five (4.3%) had a bump. The odds of aneuploidy in the presence of a chorionic bump were higher than those in the absence of a chorionic bump, although this difference was not statistically significant (odds ratio [OR] 2.3, 95% CI: 0.8-6.7). In subgroup analyses, odds of aneuploidy were four times higher in the bump group than in the no bump group among those with a sonographically isolated bump (OR 4.5, 95% CI: 1.5-13.5) and 15 times higher among those with an isolated bump and increased first-trimester aneuploidy risk (OR 15.0, 95% CI 2.4-93.3).

CONCLUSIONS

Agreement in identifying chorionic bumps is near-perfect. A sonographically nonisolated chorionic bump is not associated with significant additional aneuploidy risk, whereas a sonographically isolated chorionic bump confers a significantly increased likelihood of aneuploidy in high-risk fetuses. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 45:3-7, 2017.