This newest member of the SOMATEX line of soft drainage sets features a drainage loop the can be completely closed through use of an attached fixing thread. This minimizes any risk of drainage placement while at the same time offering superior drainage efficiency. The opening holes in the unit can be secured in an optimal position for effective drainage,. At the same time the unit is axially secured so as to prevent any chance of its dislocation. When the thread has been separated the catheter can be removed without causing trauma to the patient while the drainage is either being removed or replaced. The drainage catheter itself has been constructed of a soft, non-folding material, yet is has been designed for safe insertion and the ability to maintain its position with absolute reliability.