A catheter for guiding a body fluid of a subject includes an elongated body, an adjusting mechanism, and a valve mechanism. Moreover, the elongated body further includes a first portion, a second portion and a flexible portion between the first and the second portions. The second portion includes a passageway for the body liquid. The valve mechanism closes to the inlet of the passageway. Furthermore, the flexible portion expands when the adjusting mechanism is in a first state to prevent the catheter from being removed from the subject, and the flexible portion retracts when the adjusting mechanism alters to a second state to allow the catheter to be removed from or inserted into the subject. Hence, the body fluid is directed to enter the passageway via the inlet and exit via the outlet when the adjusting mechanism is not in the second state.一種可引流個體內體液之導管，其包含：長形本體、調整機構、閥門機構。而且長形本體還包含：第一部分、第二部分、介於第一部分與第二部分間的可撓部分。第二部分具有一個可讓體液流過之通道。閥門機構位於接近通道之入口。而且當可撓部分展開以將導管錨定於個體內時，調整機構是處於第一狀態，並且當可撓部分縮回而使得導管可插入或拔出個體時，調整機構改變為處於第二狀態。因此，當調整機構不是處於第二狀態時，體液被導引經由第二部分之入口進入通道並經由第二部分之出口離開。
