Introduction: There is little study on the incidence and clinical significance of isolated distal deep vein thrombosis (IDDVT) in kidney transplant recipients (KTR). IDDVT in kidney transplantation recipient is difficult to make decision about treatment and follow-up because it is not common in KTR and there are several limitations using anticoagulation; decreased renal function, drug interaction and frequent needs of invasive procedure.
Material and Method: We performed a protocol duplex ultrasound scan (DUS) at postoperative day (POD) 1week, 2week, 1month, 3month, 6month and 1 year from February 2010. Venous thromboembolism prophylaxis was performed with gradual compression stocking or intermittent pneumatic compression device only. Between February 2010 and April 2016, we retrospectively analyzed patient medical records. A preference of treatment was changed; from 2010 to 2013, we had ‘anticoagulation first’ strategy and after 2014 we have had ‘serial follow-up first’ strategy. We choose ‘anticoagulation first’ strategy in specific case who had large thrombus burden (involvement of long segment over 5cm and multiple lesion over two) with low bleeding risk. The effect of treatment was determined by follow-up DUS, maintenance of thrombus was considered to need further treatment in early phase but definite extension of thrombus was treated and maintenance of thrombus was observed in late phase.
Results: During the period, 862 cases of KT wwere performed and there were 60 cases (6.9%) of DVT. Eleven cases were DVT involved above popliteal vein and 49 cases were IDDVT (81.6%). All cases of IDDVT were asymptomatic. Time of diagnosis was most common during 2weeks and 3 cases were diagnosed later than 3rd month after KT. Twenty-one patients (42.8%) was treated by ‘anticoagulation first’ strategy and 28 patients (57.1%) was managed by ‘serial follow-up first’ strategy. Five patients of ‘serial follow-up’ first group were taken anticoagulation for maintenance of thrombus on follow-up DUS in early 2014, after then there was no one who needs treatment conversion. Duration of anticoagulation was planned 3month but only fifteen patients completed. Eleven patients stopped early due to bleeding complication, invasive procedure, insufficient graft function and drug interaction. A thrombus extension to proximal deep vein was not observed in both anticoagulation and serial follow-up groups. 
Discussion: IDDVT in KTR have low incidence and good prognosis and extension to proximal vein is may effectively prevented by mechanical prophylaxis and intentive surveillance.