Rungjirajittranon T, et al. - Researchers determined the prevalence and features of thrombosis and bleeding among patients with newly-diagnosed myeloproliferative neoplasm (MPN). In this systematic review and meta-analysis, they analyzed data from 29 cohort studies (8 prospective and 21 retrospective) with 13,436 patients with MPN identified from the MEDLINE and EMBASE databases from inception to August 2018 when searched using the terms for myeloproliferative neoplasms, thrombosis, and bleeding. At diagnosis, 20.0% was the estimated pooled prevalence of overall thrombosis among patients; pooled prevalence of arterial thrombosis and of venous thrombosis was 16.2% and 6.2%, respectively. Cerebrovascular disease/transient ischemic attack, coronary heart disease, and deep venous thrombosis were documented as the commonly developed thrombotic events. Among patients who were newly diagnosed with MPN, the pooled prevalence of hemorrhagic complications was 6.2%. Gastrointestinal, mucosal, and cutaneous bleeding were commonly encountered. Overall, MPN was commonly seen with thrombosis and bleeding, initially. For patients who present with unexplained thrombosis or abnormal bleeding, MPN should be considered.