The treatment of atrial-extention Wilms` tumor thrombus is surgical excision after chemotherapy. Atriotomy with cardiovascular by-pass is the one of the most common method for this procedure. Herein, we aimed to present a case of Wilms` tumor with a tumor thrombus extending into the right atrium totally excised with retrohepatic cavatomy. A 3.5 year-old girl was admitted with the symptom of dysuria. The examinations revealed a mass consistent with Wilms` tumor in the middle and lower poles of the left kidney. Doppler ultrasound and Echocardiographic examinations showed a tumor thrombus extending into the right atrium and some pulmonary nodules which were interpreted to be metastasis. Wilms` tumor was histopathologically diagnosed by an open biopsy. After three courses of chemotherapy imaging studies revealed that the atrial axtention of the tumor thrombus persisted. The tumor thrombus was found to be fibrotic on the magnetic resonance imaging scan of the patient. Therefore, nephroureterectomy along with the excision of the tumor thrombus from the inferior vena cava was done with intraoperative continuous trans-esophageal echocardiography (TEE). The suprarenal and retrohepatic vena cava were exposed by dissecting and ligating all short hepatic veins and completely mobilizing the right lobe of the liver. The thrombus was dissected out via Vertical cavatomy at the retrohepatic level. TEE confirmed complete removal of the thrombus from the atrium; Vena cava was then repaired. There was no need for a blood transfusion, or cardiovascular by-pass (CPB) during the operation. Total exposure of the retrohepatic and subdiaphragmatic vena cava using transplantation techniques is an effective method for the excision of a tumor thrombus without sternotomy, atriotomy and CPB, avoiding possible intra- and postoperative complications in selected cases of Wilms` tumor with intraatrial thrombus extension. The case emphasises the importance of multidisciplinary communication and collaboration.

Keywords: Wilms` tumor thrombus, children, retrohepatic vena cava disection