Background: Tumour thrombus is a serious complication associated with cancers. This condition often involves the inferior vena cava and pulmonary arteries, leading to significant morbidity and mortality. Traditional treatment modalities, carry inherent risks and may not be suitable for all patients. Consequently, there is a growing interest in minimally invasive techniques to manage tumour thrombus effectively. Purpose: This study aims to review our institution's experience with inadvertent tumour thrombus retrieval during computer-assisted vacuum thrombectomy (CAVT) procedures and to contextualize these findings within the existing literature. Methodology: A retrospective review was conducted of patients who underwent CAVT at our institution between 2023 and June 2025. Cases were identified where histopathological analysis of the retrieved specimen confirmed the presence of malignant cells. A comprehensive literature review was also undertaken to compare our findings with existing reports. Results: A total of five cases were identified. The cohort included one arterial and four venous thrombectomies. Final histopathological diagnoses were renal cell carcinoma, embryonal carcinoma, endometrial carcinosarcoma, and metastatic poorly differentiated carcinoma. Of these, one was an expected tumour thrombus, two had known malignancies, and two were new malignancy diagnoses identified during the same admission, with the CAVT finding supporting the initial diagnosis. Notably, our series includes arterial tumour emboli, a rarity in published literature and the use of CAVT for tumour thrombectomy appears to be a novel application with only a single case previously reported. Conclusion: Our centre’s experience demonstrates that malignant thrombus can be an unexpected finding in both arterial and venous systems during CAVT procedures. These findings underscore the critical importance of routine histopathological analysis of unusual retrieved endovascular specimens to avoid missing or delaying a diagnosis of malignancy.