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Lower Limb Deep-Vein Thrombosis
“Venous ultrasound (US) has replaced contrast venography has replaced contrast venography (CV) as the primary diagnostic tool in the investigation of suspected deep venous thrombosis (DVT) in most hospitals. The main benefits for the use of venous US are its non-invasive nature and lack of exposure to ionizing radiation. The clinical importance of below-knee DVT is a source of great debate. The main concerns with below-knee DVT are the short-term risk of above-knee propagation and the longer-term risk of post-phlebitic syndrome” (p. 858).
Methods
“Symptomatic patients who under, went CV for suspected DVT had clinical and imaging details entered on a venous thromboembolism database. Venography was the principle imaging technique. One-thousand, five-hundred and seventy-two patients undergoing CV because of a clinical suspicion of DVT at a large teaching hospital were prospectively studied. Doctors were requested to complete a short datasheet that recorded clinical and demographic information of each patient. Statistical analyses were carried out using the Mann-Whitney U-test, the binomial test, and the chi-square test” (p. 859).
Results
“Results found that males were almost twice as likely as females to have a positive result.
The proportion of males and females who had examinations of the left leg only, right leg only, or both legs proved to be similar. Left-sided thrombi were more common than right-sided thrombi. This suggests the detected left-sided predominance is evident above the knee and becomes more pronounced in more proximal veins” (p. 860).
Conclusion
“Venography is the primary test in the diagnosis of DVT although US has many advantages. These advantages include rapidity, safety, availability, and non-invasive testing. Debate continues to surround the clinical importance of detecting below-knee DVT, but there is no doubt that undetected calf thrombi may unpredictably propagate above the knee to give rise to clinically relevant thromboembolism. The threshold for investigation of suspected DVT generally drops after the replacement of CV with US as the principle screening tool” (p. 861). “Almost a third of positive cases in this study were identified as isolated below the knee thrombi. This type of thrombi was more difficult to detect by non-invasive means” (p. 858). The aim to evaluate accuracy of a simple clinical assessment of DVT was variable in this study.
References
Cowell, G. W., Murchisaon, J. T., Reid, J. H., & Simpson, A. J. (2007). A profile of lower limb
deep-vein thrombosis: the hidden menace of below0kneee DVT. Clinical Radiology,
62:9, 858-863.
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