Microwave Cauterisation After Tumour Biopsy Shows Promise for Children at High Bleeding Risk

For children with suspected abdominal tumours, the biopsy needle that delivers a diagnosis can also, in rare cases, deliver serious complications. Two risks loom largest: bleeding from the punctured organ, and the seeding of tumour cells along the needle track as it is withdrawn. Now a team at Hong Kong Children’s Hospital has reported an early but striking solution. In a study published in CVIR Oncology, interventional radiologists describe cauterising the biopsy tract with a microwave ablation antenna immediately after sampling, and they recorded a 100 percent technical success rate with no haemorrhage, no skin burns and no tumour seeding across seventeen lesions in eleven paediatric patients.

The technique builds on a concept that has gained traction in adult interventional radiology over the past two decades. When a core biopsy needle pierces a hypervascular organ such as the liver or spleen, it leaves behind a channel that can continue to ooze after the procedure. Plugging that channel with embolic materials such as gelatin sponge slurry is one option, but thermal cauterisation offers a different mechanism: instead of mechanically blocking the tract, it coagulates the tissue along it, producing a zone of necrotic, sealed tissue that resists bleeding. Radiofrequency electrodes have been used for this purpose in adults, with studies reporting technical success rates as high as 98 percent and no major bleeding complications.

What has been missing, the Hong Kong team notes, is evidence in children. Paediatric oncology patients present particular challenges: smaller organs, thinner capsules, and tumours such as hepatoblastoma and hepatocellular carcinoma that can be both hypervascular and prone to seeding. The researchers therefore designed a retrospective review of consecutive patients aged eighteen or younger who underwent image-guided biopsy of a suspected intraabdominal tumour followed by tract cauterisation at their tertiary paediatric oncology centre between May 2019 and May 2024. The decision to cauterise was made at the operator’s discretion, based on the perceived risk of post-biopsy bleeding or tumour seeding.

The technical execution is elegant in its simplicity. All procedures were performed under general anaesthesia by three interventional radiologists with ten to twenty-five years of experience. A fifteen-gauge coaxial cannula was advanced into the target lesion under imaging guidance, and a sixteen-gauge core biopsy needle was passed through it to obtain tissue samples, with a median of three cores per lesion. Then, immediately after sampling, a sixteen-gauge microwave ablation antenna was inserted through the very same coaxial cannula. The antenna delivered microwave energy at forty watts in pulsed mode for at least thirty seconds, all under real-time ultrasound guidance. The radiologists watched for an echogenic zone, the bright cloud of microbubbles and tissue change that signals thermal coagulation, to spread until it fully covered the biopsied area. The antenna was then gradually withdrawn to the organ capsule, cauterising the entire tract on the way out.

The choice of a sixteen-gauge microwave antenna rather than a slimmer radiofrequency applicator was deliberate. International guidelines for paediatric liver tumour biopsies, including those from the Pediatric Hepatic International Tumour Trial, recommend obtaining at least ten cores of tissue with a sixteen-gauge device, which requires a robust outer cannula. Recent advances in microwave technology have allowed effective energy delivery through progressively smaller antennae, making it possible to match the calibre of the coaxial system already in place. Microwave energy also has physical advantages: it heats tissue faster and less dependently on tissue conductivity than radiofrequency current, producing broader coagulation zones in less time.

The results were unambiguous. Eleven patients, with a mean age of nine years and ranging from four months to eighteen years, underwent cauterisation of seventeen lesions, the vast majority in the liver. Every patient carried at least one risk factor for post-biopsy bleeding, such as a subcapsular lesion lying within a centimetre of the organ capsule, an avidly enhancing hypervascular mass, renal insufficiency, or cirrhosis. Technical success, defined as the absence of bleeding within the first twenty-four hours, was achieved in all seventeen procedures. Haemoglobin levels before and after the procedures were statistically indistinguishable, and follow-up extending to a mean of 562 days revealed no cases of tumour seeding along the biopsy tract.

Perhaps the most compelling evidence came from a single patient’s before-and-after experience. A seventeen-year-old girl with cirrhosis, portal hypertension and thrombocytopenia had previously undergone a biopsy of a hepatic lesion with the tract plugged using gelatin sponge slurry. Roughly thirty minutes later she developed massive haematemesis, vomiting around 450 millilitres of fresh blood. Contrast-enhanced CT revealed haemobilia, with contrast extravasating into the biliary tree, and her haemoglobin fell from 10.3 to 7.3 grams per decilitre, requiring two units of packed red cells and intensive care monitoring. When the lesion enlarged over the following year and a repeat biopsy was needed, the team used microwave tract cauterisation instead. This time there were no haemorrhagic complications at all, and the biopsy confirmed well-differentiated hepatocellular carcinoma.

The case illustrates why the authors argue that thermal cauterisation may outperform embolic plugging. Gelatin sponge can stop bleeding across the organ capsule, but it cannot necessarily control bleeding within the lesion itself or into the biliary system. Animal studies have shown radiofrequency cauterisation outperforming both gelatin sponge and histoacryl-lipiodol embolisation in reducing post-biopsy bleeding, including in coagulopathic subjects. Thermal ablation also sidesteps two other hazards of embolic agents: the risk of inadvertent non-target embolisation when liquid agents migrate, and the possibility of severe anaphylaxis, which has been reported with gelatin-based haemostatic materials. A recent meta-analysis further found that concurrent ablation of the biopsy tract combined with a coaxial technique reduces the rate of needle tract seeding in liver biopsies, and one laboratory study showed that cauterisation cut the proportion of viable tumour cells clinging to a biopsy needle from 17.9 percent to zero.

The authors are candid about the limitations. The cohort is small, the follow-up period is limited for assessing tumour seeding, and there is no control group, so the study should be read as an exploratory feasibility and safety assessment rather than definitive proof of superiority. There is also the question of cost: each microwave ablation antenna costs roughly 1,000 euros in the team’s locality, and only about 6.7 percent of the 165 intraabdominal tumour biopsies performed during the study period actually required tract cauterisation. The researchers suggest that the patients most likely to benefit are those with consumptive thrombocytopenia, coagulopathy, or tumours with high seeding risk such as hepatocellular carcinoma, and they point to newer, lower-profile microwave antennae designed for thyroid nodule ablation as potential lower-cost alternatives.

Even with those caveats, the study marks a meaningful step for paediatric interventional radiology. It demonstrates that a procedure refined in adults can be adapted to children using equipment already compatible with standard paediatric biopsy protocols, and that it can do so with an unblemished safety record in a deliberately high-risk cohort. For the small subset of children whose tumours and physiology make a routine biopsy genuinely dangerous, microwave tract cauterisation may offer a way to obtain the tissue that diagnosis demands while keeping the needle’s parting footprint sealed, sterile of viable tumour cells, and dry.

Subject of Research: Microwave ablation tract cauterisation after percutaneous biopsy of intraabdominal tumours in children

Article Title: Tract cauterisation by microwave ablation following percutaneous biopsy of intraabdominal tumour in children

Article References: Chen, W. L. J., Fung, K. F. K., Liu, A. P. Y., Chung, H. Y. P., Chiang, A. K. S., Cho, H. Y. D., & Kan, Y. L. E. (2025). Tract cauterisation by microwave ablation following percutaneous biopsy of intraabdominal tumour in children. CVIR Oncology, 1(1), Article 13. https://doi.org/10.1007/s44343-025-00015-1

Image Credits: AI Generated

DOI: 10.1007/s44343-025-00015-1

Keywords: microwave ablation, tract cauterisation, percutaneous biopsy, paediatric oncology, interventional radiology, liver tumours, hepatoblastoma, tumour seeding, post-biopsy haemorrhage, coaxial technique, ultrasound guidance, CVIR Oncology