Purpose or Case Report: Slow-flow vascular malformations, most commonly multifocal or diffuse venous (VM), venous-lymphatic (VLM) and capillary-lymphatic-venous malformations (CLVM), are associated with coagulation abnormalities affecting hemostasis and thrombosis and increase risk of hematological complications with procedural interventions. Although not completely understood, pathogenesis of this coagulopathy, termed localized intravascular coagulopathy (LIC), is presumed secondary to stagnant blood in abnormal vessels and consumption of coagulation factors. LIC is characterized by elevated D-dimer, low fibrinogen, and/or mild thrombocytopenia and may progress to disseminated intravascular coagulopathy following surgical procedures. In patients with high-risk malformations, hematologic complications of sclerotherapy and use of low molecular weight heparin (LMWH) as a preventative measure have not been well studied.
Methods & Materials: This study reviewed medical records of patients with slow-flow vascular malformations who underwent sclerotherapy at our institution from July 2008 to December 2016 with LIC as defined by high D-dimer (5 times upper limit of normal), fibrinogen <150mg/dL and/or platelet count <150K/mcL. Hematologic complications included any clinically relevant bleeding or clotting abnormality that occurred 2 weeks post-sclerotherapy and/or while on LMWH prophylaxis, up to 2 weeks, prior to sclerotherapy. Relevant hematuria included gross and large microscopic hematuria. Use of LMWH including dose, frequency and course length was evaluated.
Results: Forty of 300 patients had slow-flow vascular malformations with associated LIC and underwent a total of 241 sclerotherapy procedures. In 87% of cases, LMWH was administered at 0.5mg/kg/dose once daily for 2 weeks before and after sclerotherapy. One patient on LMWH developed pulmonary emboli, presumably from deep vein thrombosis of the treated extremity. Two patients developed transient, asymptomatic hematuria. In 5 patients fibrinogen levels dropped below 100 mg/dL post-sclerotherapy for which cryoprecipitate was administered. No intra-op bleeding or thrombotic events occurred.
Conclusions: Prophylactic LMWH use was common in this patient population and did not appear to increase the risk of significant bleeding before, during or after sclerotherapy. In children receiving LMWH, thrombotic complications after sclerotherapy appear rare but may still occur.