Deep venous thrombosis (DVT) and pulmonary thromboembolism (PTE) are serious problem of total knee replacement(TKR). These diseases may be caused by a thrombus formed during the TKR operation. Therefore, understanding the flow volume of thrombus is important for curing and preventing PTE. In this paper, we tried to understanding the situation of theflow of thrombus by using transesophageal echocardiography movies. We applied the signal processing technique the FSET toextract the anomalous information from ultrasonic echo image. As a result of processing, the time change of the flow volume of thrombus was confirmed.