Uterine carcinosarcoma is a rare, aggressive tumor with several cases in the literature reporting cardiac tumor thrombus involvement. In this case report, we describe a 72-year-old female with a history of uterine carcinosarcoma, who presented with extensive thrombus in the Inferior Vena Cava (IVC) and right atrium. The patient underwent an aspiration thrombectomy which aided in intravascular debulking of the thrombus. Histopathological analysis of the thrombus revealed tumor thrombus. In cryptic cases of tumor thrombus, thrombectomy with histopathological analysis can help confirm the diagnosis of metastatic disease and help guide oncologic staging and further therapy.