EARLY DETECTION OF POSTOPERATIVE DEEP-VEI N THROMBOSIS WITH DUPLEX ULTRASOUND SCANNING IN ORTHOPEDIC-SURGERY - A RETROSPECTIVE STUDY OF 1647 PATIENTS

Introduction This study was undertaken to estimate the efficiency of d uplex ultrasound scanning and its utility to detect deep vein thrombos is in orthopedic patients and to describe their features. Material and methods A total of 1647 in-patients, all receiving low-molecular-weig ht heparin, were investigated from 1989 to 1993, either for screening because of a high risk of thrombosis (asymptomatic group: 930 patients , mean age + SD: 63 + 17 years) or for clinical suspicion of deep vein thrombosis (symptomatic group: 717 patients, mean age + SD: 57 + 21 y ears). Difference between the two groups mean ages was significant (p < 10(-8)). An Hitachi EUB 450 duplex and an Acuson colour duplex 128 X P, with 3,5 MHz and 7,5 MHz linear probes were used. Veins were tested for compressibility in the transverse view from caval site to both an kles. Retrospective analysis of patients' database results was done. R esults There was no significant difference in deep vein thrombosis rat e between screening asymptomatic group (356/930: 38 per cent) and symp tomatic group (2531717: 35 per cent). There was a linear relation, in the 2 groups, between age and deep vein thrombosis rate, from 10 per c ent before twenty to 45 per cent after eighty years old. For a relativ e risk to have thrombosis detected before twenty definite at 1, it was 2,1 for 20-29, 4,9 for 40-49, 6,2 for 60-69 and 8,6 later than 80 yea rs old. Proximal deep vein thrombosis was detected in only 5 per cent (87/1647) of patients. Distal muscular soleal veins were the most usua l involved sites of thrombosis. Isolated soleal thrombosis were detect ed in 16 per cent (270/1647) of patients. There was no significant dif ference between the deep vein thrombosis rate after total knee or hip arthroplasty among selected patients for duplex scanning from 1989, an d the true prevalence assessed among all the patients who have undergo ne total hip or knee arthroplasty during the last 6 months. Discussion Pessimistic results previously reported for duplex screening among as ymptomatic patients are not confirmed. Calf vein thrombosis rate asses sed with duplex exceeds by 15 to 20 per cent the rates assessed by;con trast venography, among patients receiving low molecular weight hepari ns. That difference could be attributed to the isolated muscular solea l thrombosis usually missed at contrast venography. Conclusion Deep ve in thrombosis rate among orthopedic surgical patients, is much higher when detected with Duplex ultrasound scanning than detected with contr ast venography, and is related to patient age. Soleal vein thrombosis is the most prevalent. Duplex ultrasound scanning is an efficient and useful screening method for deep vein thrombosis in orthopedic surgery . Mechanical calf venous pump stimulation in association with low mole cular weight heparin, has to be evaluated in attempting to reduce thos e muscular soleal veins thrombosis.