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.