A catheter for guiding a body fluid of a subject, comprising: an elongated body having a proximal tip, a distal tip and further including a first portion , a second portion and a flexible portion between the first and the second portions, and the second portion includes a circumferential wall defining a passageway for the body liquid, the passageway further includes an inlet and an outlet ; and an adjusting mechanism with two opposite ends, the first end engages the first portion and the second end engages the second portion proximate to the inlet of the passageway, the adjusting mechanism is adapted to alter between different states; wherein the adjusting mechanism is in a first state when the flexible portion expands to anchor the catheter inside the subject, and the adjusting mechanism alters to a second state when the flexible portion retracts to allow insertion or withdrawal of the catheter to/from the subject; wherein the body fluid is directed to enter the passageway via the inlet of the second portion and exit via the outlet of the second portion, characterised in that the second end of the adjusting mechanism comprises a first valve mechanism proximate to the inlet of the passageway, the body fluid can enter the passageway via the inlet when the first valve mechanism is opened and the body fluid is blocked from entering the passageway when the first valve mechanism is closed, wherein the adjusting mechanism comprises a controlling wire configured to open or close the first valve mechanism , and the flexible portion further expands such that the flexible portion and the first portion are more securely anchored within the subject when the controlling wire is pulled to open the first valve mechanism . an elongated body having a proximal tip, a distal tip and further including a first portion , a second portion and a flexible portion between the first and the second portions, and the second portion includes a circumferential wall defining a passageway for the body liquid, the passageway further includes an inlet and an outlet ; and an adjusting mechanism with two opposite ends, the first end engages the first portion and the second end engages the second portion proximate to the inlet of the passageway, the adjusting mechanism is adapted to alter between different states; wherein the adjusting mechanism is in a first state when the flexible portion expands to anchor the catheter inside the subject, and the adjusting mechanism alters to a second state when the flexible portion retracts to allow insertion or withdrawal of the catheter to/from the subject; wherein the body fluid is directed to enter the passageway via the inlet of the second portion and exit via the outlet of the second portion, characterised in that the second end of the adjusting mechanism comprises a first valve mechanism proximate to the inlet of the passageway, the body fluid can enter the passageway via the inlet when the first valve mechanism is opened and the body fluid is blocked from entering the passageway when the first valve mechanism is closed, wherein the adjusting mechanism comprises a controlling wire configured to open or close the first valve mechanism , and the flexible portion further expands such that the flexible portion and the first portion are more securely anchored within the subject when the controlling wire is pulled to open the first valve mechanism . <EOS>