Prospective cohort study of hematoma incidence after ultrasound-guided vacuum-assisted breast excision

Ultrasound-guided vacuum-assisted excision (US-VAE) is increasingly preferred for benign and B3 breast lesions, yet post-procedural hematoma remains the commonest early complication. To prospectively quantify the 7-day incidence of clinically relevant hematoma after US-VAE, describe its clinical course, and identify independent risk factors. Consecutive women ≥ 18 years undergoing US-VAE were enrolled in this single-center prospective study (November 2022 - November 2024). The analytic cohort comprised 672 procedures in 658 women (97.5% follow-up). Standard US-VAE was performed with 7-, 9-, or 12-gauge probes. Peri-procedural compression time, lesion metrics, and anticoagulant exposure were recorded prospectively. Clinically relevant hematoma was predefined as an ultrasound-visible post-excision collection > 20 mm, or any symptomatic or intervention-requiring ultrasound-visible collection within 7 days. Associations with 7-day hematoma were evaluated using multivariable logistic regression with bootstrap internal validation. Secondary outcomes were time to ultrasound-confirmed resolution, need for intervention, and pain. The final cohort comprised 672 procedures in 658 women (mean age 47.7 ± 11.1 years); race/ethnicity was not routinely recorded. A total of 103 clinically relevant hematomas were observed, giving a 7-day incidence of 15.3% (95% CI 12.6–18.1). Median hematoma resolution time was 16 days (95% CI 14–18); 93% resolved by day 30. Minor intervention was required in 10.7% of hematomas; no surgical evacuations occurred. Multivariable logistic regression identified four independent predictors: lesion diameter > 20 mm (adjusted OR 2.43, 95% CI 1.47–4.02), lesion depth < 10 mm (OR 1.93, 95% CI 1.18–3.17), peri-procedural anticoagulant use (OR 2.57, 95% CI 1.61–4.17), and compression time < 5 min (OR 1.73, 95% CI 1.08–2.78). The risk model showed good discrimination (bootstrap-corrected C-statistic 0.79) and calibration (slope 0.94). Clinically relevant hematoma complicates approximately one in six US-VAE procedures but is usually self-limiting and rarely requires invasive management. Larger or shallow lesions, peri-procedural anticoagulant exposure, and brief post-procedure compression significantly increase risk. Extending compression duration and optimizing anticoagulant management may further reduce complications. These data also support counseling higher-risk patients that most hematomas resolve within 30 days and only a minority require minor nonoperative intervention.