Complex Venous Thromboembolism in a Young Woman With Multisystem Manifestations: A Case Report.

Venous thromboembolism (VTE) in adolescents is rare and often necessitates a comprehensive evaluation for both inherited and acquired prothrombotic conditions. We report the case of an 18-year-old female who initially presented with cerebral venous sinus thrombosis (CVST). Anticoagulation with warfarin was complicated by massive gastrointestinal bleeding, followed by deep vein thrombosis (DVT) and recurrent thrombotic events, including superior mesenteric venous thrombosis with bowel infarction. Laboratory investigations revealed sickle cell trait (HbS 38.3%), heterozygous mutations in lymphotoxin alpha (LTA C804A), Factor V R2 (H1299R), and methylenetetrahydrofolate reductase (MTHFR C677T), with normal homocysteine levels. The autoimmune panel was negative apart from borderline high cardiolipin immunoglobulin G (IgG). Owing to recurrent bleeding, anticoagulation proved challenging, and she was ultimately managed with apixaban and clopidogrel. This case illustrates the synergistic impact of multiple mild thrombophilic factors and sickle cell trait, underscores the need to consider mesenteric venous thrombosis in abdominal emergencies, and highlights the clinical challenge of balancing thrombosis prevention with bleeding risk.