A catheter device (1) for providing access to a body cavity of a patient comprises a tube (10) and an inserting shell (11) arranged on the tube (10) and constituted to be fastened to an insertion guide (3) for inserting the catheter device (1) into a body opening (C) of a patient (P). Herein, the inserting shell (11) comprises an opening (111) into which a thread (300) of the insertion guide (3) is insertable for fastening the catheter device (1) to the insertion guide (3). In this way, a catheter device is provided which, in an easy and efficient manner, allows for the fastening to an insertion guide.