A one-piece catheter (30) and manufacturing method therefor are disclosed. The catheter (30) includes a catheter tube (33) and an adapter (31). The catheter catheter tube (33) includes a tip (331) at one end and an end portion (332) at another other end. The adapter (31) can be configured for receiving a septum (402). The adapter (31) includes a narrow opening. The end portion (332) of the catheter tube (33) is connected to the adapter (31 ) at the narrow opening for fluid communication between the catheter tube (33) and the adapter (31 ). The catheter tube (33) and adapter (31) are formed as a one-piece element that is preferably injection molded in a single-shot process. Additional elements, such as one or more retention tabs (313) for attaching to a base can be formed on the catheter (30). The one-piece catheter (30) can be made by a single-shot injection molding process. Additional structures, such as a base can be attached to the catheter (30) by a second-shot injection molding process.