Arterial Thrombosis Following Umbilical Artery Catheterization: Visualising Uncommon Neonatal Intensive Care Unit (NICU) Complications.

Background: Right internal iliac artery (RIIA) thrombosis is an extremely rare but serious complication associated with umbilical artery catheter (UAC) malposition in neonates in the Neonatal Intensive Care Unit (NICU). Timely diagnosis and appropriate management are essential to prevent long-term sequelae. Case Report: We present the case of a term neonate with hypoxic-ischaemic encephalopathy (HIE), who developed RIIA thrombosis secondary to UAC malposition, highlighting the role of bedside Doppler ultrasound in diagnosis and monitoring, and the success of a conservative therapeutic approach. Discussion: A term male neonate with HIE was undergoing therapeutic hypothermia when violaceous macular skin lesions appeared on the right buttock and loin shortly after UAC insertion. Imaging confirmed malposition of the catheter in the RIIA. The catheter was promptly removed, and the patient was closely monitored both clinically and with serial Doppler ultrasounds. Approximately 6 h after catheter removal, Doppler ultrasound revealed a clot in the RIIA. The patient was managed conservatively with continuous infusion of unfractionated heparin (10 IU/kg/h) and topical anti-inflammatory therapy. The skin lesions resolved within 36 h, and Doppler at 48 h post-removal confirmed re-established arterial flow. No invasive interventions were required. This case underscores the importance of careful catheter placement and the utility of bedside Doppler ultrasound in detecting and monitoring vascular complications. Moreover, prompt recognition and conservative treatment of arterial thrombosis can result in optimal outcomes, even in neonates with complex clinical conditions such as birth asphyxia.