Summary
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 of asymptomatic DVT. Failure of non invasive diagnostic methods to
detect thrombi in asymptomatic patients has been suggested to be due to the features
of thrombi in these patients. The aim of this study was to assess the distribution
and the occlusiveness of thrombi in a series of 321 asymptomatic hip surgery patients
with adequate bilateral venography of the lower limbs.
Venography was performed 10 ± 1 days after hip surgery. DVT was found in 180 limbs
(28.0%). The distribution of thrombi was as follows: 26 (14.4%) isolated proximal
thrombi, 55 (30.6%) proximal and distal thrombi, 99 (55.0%) isolated calf thrombi.
We found 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 popliteal 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 observed in 118,13
and 89 cases of the 220 distal thrombi. These thrombi were non occlusive in 61 (51.7%),
10 (76.9%) and 30 (33.7%) of the cases.
We conclude that the majority of thrombi found in asymptomatic hip surgery patients
are non occlusive. In view of this, non invasive diagnostic methods based upon venous
flow measurement will be unlikely to improve the diagnosis of asymptomatic DVT. The
high incidence of isolated superficial femoral vein thrombosis necessitates that real-time
B-mode ultrasonography should be performed examining the entire proximal venous system.
