Prospective Analysis of the Mechanisms Underlying Ineffective Deep Vein Thrombosis Prophylaxis in Necrotizing Pancreatitis

Background: Patients with necrotizing pancreatitis (NP) have the highest rate of venous thromboembolism (VTE) of any hospitalized patient (57%). We hypothesized that VTE prophylaxis might be inadequate in the setting of this profound inflammatory disease and that early detection of deep vein thrombosis would limit pulmonary embolism. Study Design: All patients with NP treated at a single center between August 2018 and December 2019 were enrolled in prospective, weekly VTE screening, including 4-extremity duplex ultrasound. Routine chemoprophylaxis included low-molecular-weight or unfractionated heparin. Peak serum anti-factor Xa concentration was measured during weekly screening (goal prophylaxis 0.2 to 0.4 IU/mL). Results: Eighty-five patients with NP underwent a total of 201 screening events (mean 2.4 per patient). VTE developed in 55 patients (65%), including splanchnic vein thrombosis in 41 patients (48%) and extremity deep vein thrombosis (eDVT) in 32 patients (38%). Extremity DVT was diagnosed a mean ± SD of 44 ± 30 days after NP onset. Symptomatic pulmonary embolism was prevented in all patients diagnosed with eDVT and no contraindication to anticoagulation (0 of 29). Prophylactic anti-factor Xa concentration was only achieved in 21% (12 of 57 screening events); no eDVTs developed in patients achieving prophylactic anti-factor Xa concentration. Conclusions: In patients with NP, identification of eDVT by screening ultrasound permits early treatment and prevents symptomatic pulmonary embolism. Fixed dosing of chemical prophylaxis is inadequate in most patients with NP and likely contributes to the mechanism of increased VTE in NP.