Balloon catheter system for sealing puncture points or openings in body cavities, hollow organs or in percutaneous drainage operations in mammals, comprising: a filling catheter for filling medium comprising: a shaft having a lumen extending there through; a first balloon, positioned on the distal end of the shaft; and a second balloon arranged proximally spaced apart from the first balloon; wherein the first and second balloons (20, 22) can be filled with the filling medium; wherein the first and second balloons (20, 22) are suitably arranged to close said puncture point or opening in the body when positioned on the two sides of said puncture point or the opening in the body and filled with the filling medium; wherein the shaft comprises a first opening (23.2) and a second opening (23.1), in fluid communication with the first and second balloons (20, 22) respectively; and wherein the shells of the two balloons (20, 22) enclose the shaft of the filling catheter; and a hollow needle; wherein the hollow needle is suitably arranged to be guided in the lumen of the shaft of the filling catheter for filling the first and second balloons (20, 22) with the filling medium; whereby, the first balloon may be firstly filled with the filling medium via the first opening (23.2) of the filling catheter using the hollow needle; and thereafter when the hollow needle is drawn back through the filling needle to the proximally situated second balloon, the second balloon may then be filled with the filling medium via the second opening (23.1) of the filling catheter; characterised in that the balloon catheter system further includes an infusion catheter arranged on the filling catheter, wherein the infusion catheter comprises a distal end that passes through the two balloons (20, 22); and wherein the shells of the two balloons (20, 22) also enclose the infusion catheter. a filling catheter for filling medium comprising: a shaft having a lumen extending there through; a first balloon, positioned on the distal end of the shaft; and a second balloon arranged proximally spaced apart from the first balloon; wherein the first and second balloons (20, 22) can be filled with the filling medium; wherein the first and second balloons (20, 22) are suitably arranged to close said puncture point or opening in the body when positioned on the two sides of said puncture point or the opening in the body and filled with the filling medium; wherein the shaft comprises a first opening (23.2) and a second opening (23.1), in fluid communication with the first and second balloons (20, 22) respectively; and wherein the shells of the two balloons (20, 22) enclose the shaft of the filling catheter; and a hollow needle; wherein the hollow needle is suitably arranged to be guided in the lumen of the shaft of the filling catheter for filling the first and second balloons (20, 22) with the filling medium; whereby, the first balloon may be firstly filled with the filling medium via the first opening (23.2) of the filling catheter using the hollow needle; and thereafter when the hollow needle is drawn back through the filling needle to the proximally situated second balloon, the second balloon may then be filled with the filling medium via the second opening (23.1) of the filling catheter; characterised in that the balloon catheter system further includes an infusion catheter arranged on the filling catheter, wherein the infusion catheter comprises a distal end that passes through the two balloons (20, 22); and wherein the shells of the two balloons (20, 22) also enclose the infusion catheter.