In critically ill (preterm) neonates, central venous catheters (CVCs) are increasingly used for administration of medication or parenteral nutrition. A serious complication, however, is the development of catheter-related thrombosis (CVC-thrombosis), which may resolve by itself or cause severe complications. | NEOnatal Central-venous Line Observational study on Thrombosis (NEOCLOT): Evaluation of a national guideline on management of neonatal catheter-related thrombosis