Patient: Male, 63-year-old Final Diagnosis: Spontaneous knot formation in central venous catheter Symptoms: Central venous catheter whit any flow • associated with pain at the insertion site of the access Medication: — Clinical Procedure: Central venous catheterization Specialty: General and Internal Medicine • Surgery Objective: Challenging differential diagnosis Background: Central venous catheterization (CVC) is indispensable in the management of critically ill patients in the emergency room and intensive care units, either to avoid the various peripheral punctures and vasoactive drugs administration in decompensated patients, or even to administer parenteral nutrition. CVC is an invasive procedure with possible mechanical, infectious, and thrombotic complications. The complete knotting of a catheter is a rare complication. The aim of this study is to report a case of a simple tight knot 2 cm from the catheter tip. We provide insights for early identification of catheter knotting, as well as its management. Case Report: A 63-year-old man with a previous history of angioplasty and non-pharmacological coronary stent in a marginal branch of the circumflex coronary artery evolved to junctional bradycardia and cardiogenic shock and was transferred to the reference hospital. He had a CVC inserted in the right jugular vein; however, it did not have any blood flow. The hypothesis of catheter knotting was suggested and confirmed through a chest X-ray. Venotomy was performed and it was successfully removed. Conclusions: Knotting in CVC obstruction is a rare complication. Recognition of this complication is essential to avoid major complications, such as catheter fragmentation and venous injury. Radiological follow-up after the procedure in patients with difficult anatomy is essential, and echo-guided catheterization should be encouraged when available. Despite the rarity of a knotted intravascular catheter, it is important to note this possible late complication that must be considered in the absence of catheter blood flow.