Chorionic bumps in early pregnancy and their link to miscarriage.

INTRODUCTION: Chorionic bumps are a rare first‑trimester ultrasound finding with uncertain prognostic significance. OBJECTIVE: To estimate the risk of miscarriage in pregnancies with a chorionic bump compared with the institutional baseline miscarriage rate in our Early Pregnancy Unit (EPU). METHODS: Retrospective cohort of consecutive pregnancies with a sonographically confirmed chorionic bump (January 2020-May 2025). Outcomes were benchmarked against the EPU's baseline miscarriage rate derived from all attendances during the study period. Prespecified secondary analyses explored whether maternal age, subchorionic haematoma (SCH), or bump size predicted outcome. RESULTS: Among 151 pregnancies with a chorionic bump, 81 miscarried (53.6%). This was substantially higher than the EPU baseline of 14.2% (2,295 miscarriages among 16,115 patients), corresponding to a near‑sevenfold increase in odds (OR 6.99; z = 9.72; p < 0.0001). Bump size and the presence of SCH were not associated with outcome. Increasing maternal age had a modest effect (OR 1.09 per year, p = 0.014). Outcomes following IVF conception were similar to, or slightly better than, spontaneous conception. CONCLUSION: The presence of a chorionic bump is a clinically important prognostic marker of miscarriage, independent of bump size or SCH.