Noncompressible Filling Defects: Propagation in Isolated Calf Vein Thrombus in the Critical Care Population

Abstract

The natural history of isolated calf deep venous thrombosis (CDVT) or noncompressible filling defects is controversial. We aimed to characterize our patient population by differentiating those who had just an isolated, asymptomatic deep venous thrombosis (DVT) limited to the calf from those with a symptomatic CDVT. The presence of edema or pain in the calf and findings of thrombus formation within the soleal, gastrocnemius, posterior tibial, or anterior tibial veins describe symptomatic CDVT. Our objective was to study the incidence, evolution, and clinical consequence of asymptomatic CDVT within the critical care population. A retrospective analysis incorporating venous duplex ultrasound scans of neurocritical care patients was performed during a 32-month period from January 2016 to September 2018. Based on a risk assessment profile score >5, a venous duplex ultrasound scan was obtained 3 days after the patient’s admission and weekly thereafter until discharge. Demographics including age, sex, comorbidities, anticoagulation status, principal admission problem, and in-hospital mortality were noted. Symptomatic patients with a diagnosis of a DVT were excluded. The development of a proximal DVT or pulmonary embolus vs resolution of the thrombus during the study period was also recorded. Approximately 5375 lower extremity venous studies were performed. CDVT was identified in 121 (2%) asymptomatic patients. The main admitting diagnosis was traumatic brain injury. The majority (83 patients) underwent follow-up scans consistent with recommendations. During the 32-month period, approximately 50% of them (42/83) had no changes, whereas 36% of patients (30/83) had a complete resolution of the calf vein thrombus. Approximately 13% (11/83) progressed while remaining asymptomatic. Of those 11 patients, 3 patients subsequently developed symptomatic above-knee DVT (3/83 [3.6%]). No pulmonary embolism was recorded. There was no recorded in-hospital mortality. CDVT was identified in only a small percentage of our high-risk patient population who remain without symptoms. Moreover, the rate of progression from asymptomatic CDVT to symptomatic above-knee DVT was only 3.6%. Asymptomatic CDVTs rarely lead to significant clinical consequences and did not correlate with hospital mortality. We recommend against repeated DVT scans after diagnosis of asymptomatic CDVT, more appropriately termed noncompressible venous filling defects, solely based on protocols and without symptoms.