Objective <p>The purpose of this study is to evaluate the feasibility and safety of using a 16-gauge microwave ablation (MWA) antenna for tract cauterisation after percutaneous biopsy of suspected intraabdominal tumours in children who have higher perceived bleeding risk or tract seeding.</p> Materials and methods <p>Retrospective review of patients aged ≤ 18&#xa0;years who underwent image-guided biopsy of suspected intraabdominal tumour followed by tract cauterisation with microwave ablation (MWA). Immediately following biopsy, a 16G MWA antenna was inserted through the same coaxial cannula to cauterise the biopsied site under real-time ultrasound guidance. Bleeding risk factors, technical success and adverse events were recorded.</p> Results <p>Seventeen lesions in 11 paediatric patients (0.4–18 years, 8 female) were included. The technical success rate was 100% (17/17). The majority (10/11, 90.9%) of patients had suspected hepatic malignancy. All patients had at least one risk factor for increased bleeding. The average tumour volume was 323.11 ± 788.9 cm³ (range, 0.4–1144.4 cm³). The median number of cores obtained was 3 (range, 2–11). There was no statistically significant difference between the mean haemoglobin (Hb) level before or after procedure (pre-procedural Hb = 9.7 ± 2.0 g/dL vs post-procedural Hb = 9.5 ± 1.5 g/dL, <i>P</i> = 0.4). No complications, including post-procedural haemorrhage, skin burn or tumour seeding along biopsy tract, were detected. The mean duration from biopsy and tract cauterisation to last clinical follow-up was 562.0 ± 291.6 days (range, 88–1018 days).</p> Conclusion <p>Tract cauterisation using a 16-gauge MWA antenna was effective in preventing haemorrhagic complications and needle tract seeding following percutaneous biopsy of intraabdominal tumour in children.</p>