Possible early sign of venous insufficiency: Presence of hematocrit effect in plantar veins.

The hematocrit effect, characterized by the separation of cellular elements in stagnant blood, manifests as fluid-fluid levels in imaging. Despite limited studies on this phenomenon, its relationship with pathology remains undefined. The aim of this study is to investigate the relationship between the hematocrit effect in plantar veins and lower extremity venous insufficiency. Patients who underwent foot magnetic resonance imaging and lower extremity Doppler ultrasonography between July 2015 and December 2020 were retrospectively scanned. The presence of hematocrit effect in magnetic resonance images and findings in Doppler ultrasound were evaluated. A total of 88 patients and 97 feet (71.1% female) were included in this study, the median plantar vein diameter was 3.38 mm (range: 1.5-6.3), and the frequency of hematocrit effect sign was % 40.2 (n = 39). The plantar veins were significantly wider in cases with hematocrit effect (4 mm [1.7-5.4] vs 2.6 mm [1.5-6.3]; P < .001), and there is a significant linear association between the presence of hematocrit effect and the severity of ultrasound findings (P = .021). The presence of the hematocrit effect in plantar veins may serve as an early indicator of venous insufficiency. Further prospective studies are warranted to explore the diagnostic utility of this phenomenon.