Silva, LJunqueira, AFPato, RFarraposo, SCruz, ARRocha, T2022-12-222022-12-222022Cureus . 2022 Sep 2;14(9):e28700.http://hdl.handle.net/10400.17/4316Cannulation of the internal jugular vein is often necessary for the management of critically ill patients. Despite being a very common procedure and performed more and more safely, several complications still occur. Horner's Syndrome (HS) is one of those complications described before the use of ultrasound as a method of guidance. HS is caused by functional interruption of sympathetic nerve supply to the eye, leading to a classic triad of ipsilateral ptosis, miosis, and anhidrosis. We present the case of a patient, in need of emergent surgery to control the hemorrhagic focus after delivery, with a transient HS secondary to internal jugular vein cannulation under real-time ultrasound guidance.engCHLC ANSCatheterizationHorner’s SyndromeInternal Jugular VeinObstetrics AnesthesiaPostpartumPtosisjournal article10.7759/cureus.28700.