DISTRIBUTION AND OCCLUSIVENESS OF THROMBI IN PATIENTS WITH SURVEILLANCE DETECTED DEEP-VEIN THROMBOSIS AFTER HIP-SURGERY

Venous thromboembolism is a leading cause of in-hospital postoperative morbidity and mortality. Postoperative deep vein thrombosis (DVT) is usually asymptomatic. A number of studies have consistently shown that the non invasive diagnostic methods are inaccurate in the screening o f asymptomatic DVT. Failure of non invasive diagnostic methods to dete ct thrombi in asymptomatic patients has been suggested to be due to th e features of thrombi in these patients. The aim of this study was to assess the distribution and the occlusiveness of thrombi in a series o f 321 asymptomatic hip surgery patients with adequate bilateral venogr aphy of the lower limbs. Venography was performed 10 +/- 1 days after hip surgery. DVT was found in 180 limbs (28.0%). The distribution of t hrombi was as follows: 26 (14.4%) isolated proximal thrombi, 55 (30.6% ) proximal and distal thrombi, 99 (55.0%) isolated calf thrombi. We fo und that 14 of the 81 proximal trombi (17.3%) involved the superficial femoral vein either as exclusive location or in association with calf veins. An involvement of common femoral, superficial femoral and popl iteal vein was observed in 37 (45.7%), 39 (48.1%) and 44 (54.3%) cases of the 91 proximal DVT. These thrombi were non occlusive in 25 (67.6% ), 22 (56.4%) and 26 (59.1%) limbs, respectively. An involvement of at least one peroneal, anterior tibial and posterior tibial veins was ob served in 118, 13 and 89 cases of the 220 distal thrombi. These thromb i were non occlusive in 61 (51.7%), 10 (76.9%) and 30 (33.7%) of the c ases. We conclude that the majority of thrombi found in asymptomatic h ip surgery patients are non occlusive. In view of this, non invasive d iagnostic methods based upon venous flow measurement will be unlikely to improve the diagnosis of asymptomatic DVT. The high incidence of is olated superficial femoral vein thrombosis necessitates that real-time B-mode ultrasonography should be performed examining the entire proxi mal venous system.