The chorionic bump: a first-trimester pregnancy sonographic finding associated with a guarded prognosis.

OBJECTIVE We describe a series of patients with a previously unreported sonographic finding, the chorionic "bump," which is an irregular, convex bulge from the choriodecidual surface into the first-trimester gestational sac. The pregnancy outcome is investigated in this series of patients and compared with the general population and infertility first-trimester control groups. METHODS We prospectively noted a cohort of 15 cases with the chorionic bump on first-trimester sonograms (in a total of 2178 patients) performed over 3 years at our institution (prevalence, 0.7%). We then compared pregnancy outcomes against 2 pregnant control groups (15 general, noninfertility patients and 15 infertility patients) who were maternal age and gestational age matched to our patient group. RESULTS The difference in outcomes between the patients with bumps and the healthy control subjects was statistically significant (7 live births versus 13 live births; P < .03), but the difference in outcomes between the patients with bumps and infertility control subjects was not statistically significant (7 live births versus 11 live births; P = .1). Bump size was not correlated with pregnancy outcome. In most patients with serial sonograms, the bump showed evolutionary changes typical for hematoma. CONCLUSIONS The finding of a chorionic bump on the first-trimester sonogram is associated with a guarded prognosis for the early pregnancy (live birth rate <50%); it probably represents a small hematoma that bulges into the gestational sac, and, in our series, most patients had a history of infertility treatments.