Objectives: Sickle cell disease (SCD) is well recognized as a hypercoagulable state, however venous thromboembolism (VTE) risk factors in children remain largely unknown. In this study, we aim to describe the clinical characteristics, outcomes and recurrence of hospital acquired VTE in patients younger than 21 years of age. Study Design/Methods: Data were extracted from electronic medical records over a 10-year period (2011-2021). Data regarding sickle cell genotype, demographics, reason for admission, location of thrombus, presence of central venous catheter (CVC), intensive care unit (ICU) admission, presence of thrombophilia risk factors, resolution of VTE, mortality, and bleeding outcomes on anticoagulation were collected. Recurrence of VTE at 1 and 5 years was assessed. Descriptive statistics were used as indicated. Results: We identified a total of 21 VTE events over the ten-year study period. Six of these events occurred in those younger than 12 years of age. Fifteen (71%) VTE events occurred in the HbSS or HbSβThal 0 genotypes compared to 8 (29%) in HbSC. Eleven (52%) patients were admitted with acute chest syndrome (ACS). Most VTE events were associated with ICU admissions (n=13, 62%) and presence of central venous catheter (n=12, 57%). Major bleeding on anticoagulation occurred in 10%.All patients had resolution of index VTE at 12 weeks. Recurrence rate for VTE at 5 years was 13%. One patient died from the VTE event. Conclusions: Our study highlights that VTE can complicate SCD in children and young adults. Hospital acquired VTE were most associated with ICU admission, CVC, and ACS, but larger studies are indicated to validate our findings.

Heterozygous mutations in Factor V Leiden (FVL) or prothrombin G20210A (PT-G20210A) are relatively common; the presence of double-heterozygosity for these mutations is rare but may be as high as 5% in patients with deep vein thrombosis (DVT). Antiphospholipid syndrome (APS) is a rare autoimmune disorder and commonly presents in adolescents and young adults. This report describes the diagnosis, treatment, and outcome for acute presentation of extensive lower extremity DVT and saddle pulmonary embolism (PE) in a previously healthy 17-year-old male found to have multiple genetic risk factors including double-heterozygosity for FVL/PT-G20210A and concurrent APS, which is rare and not well-described.