The present invention relates to a novel type of tubular insert 28 for connecting an extra-corporeal circuit 26 to a peristaltic pump 22. This tubular insert 28 comprises a loop 32 formed by a tube portion 20; the loop 32 comprises a curve 38 which extends around an axis X. The tube 20 which forms the curve 38 has an oval cross-section with a major axis M and a minor axis m perpendicular to each other, where the major axis M is longer than the minor axis m. Finally, in the tubular insert 28 according to the invention, the minor axis m of each cross-section of the tube 20 along the curve 38 is parallel to the axis X. The invention further relates to a method for producing the tubular insert 28 and to a peristaltic pump 22 suitable for operating with tubular inserts according both to the invention and to the prior art.