Background: Thromboembolism (TE) in pediatric population is rare but may be a fatal situation. There is a lack of clinical guidelines to help decision making for the use of prophylactic measures in pediatrics. This study was designed to evaluate current guidelines and risk factors for the prevention of venous thrombosis and pulmonary embolism (DVT/PE) in children.
Materials and Methods: This cross-sectional, prospective, and observational study was done between October 2014 and April 2017 in Mofid Children Hospital, Tehran, Iran. All children between 40 days to 8 years old admitted to the pediatric critical care unit (PICU) were evaluated for DVT/PE risk factors such as Glasgow coma score (GCS)< 9,complete bed rest, and central venous access catheter (CV line). 
Results: For 3 years, 1080 children aged from 40 days to 8 years who hospitalized in PICU were studied. The mean duration of ICU stay was 6 ± 1.1 days. Three hundred and forty (31.5 %) patients had at least 4 risk factors for DVT/PE. Thirty nine (11%) patients with 4 or more risk factors had diagnosed DVT/PE. Among 39 patients with thromboembolic events, 11 (1%) children died. Congenital heart disease was the independent risk factor for DVT and PE. DVT was the most common type of thrombosis (69%). 
Conclusion: This study suggested that TE is multi-factorial in children and anticoagulation therapy can be considered in hospitalized children with at least 4 risk factors. It seems that it is necessary to develop new strategies for thromboprophylaxis in PICU.