Reasons for exclusion from primary outcome analyses as well as the secondary outcome concerning ultrasound examination
pain, tCDC

The patient is unable to perform a follow-up CT venography. Reasons for this include, but is not limited toAn estimated glomerular filtration rate < 15 ml/min without ongoing dialysis treatment at the time for the CT scanThe patient dies before follow-upThe tCDC is in situ for < 7 daysAn additional central venous catheter is placed in the right-sided subclavian or internal jugular vein before the follow-up CT. Vein punctures without catheterisation are accepted (e.g. for myocardial biopsies after heart transplant surgery)Reasons for exit from the trial and for exclusion in any of the analyses will be collected and reported. Data from the questionnaire about discomfort and pain during the catheterisation procedure will be used regardless and the questionnaire about discomfort and pain during the use of the tCDC will be used if the tCDC has been in situ for ≥ 7 days.