Deep Vein Thrombosis, Pulmonary Embolism, and Infections

We’ve discussed deep vein thrombosis (DVT) and pulmonary embolism recently in this blog, in relation to air travel. Now a completely unrelated risk factor has been reported, in the UK medical journal Lancet. It seems that in the first 2 weeks following an acute urinary infection (e.g. cystitis) the risk of DVT is doubled, and the risk of pulmonary embolism, a serious consequence of DVT, is increased by 40%.

Apart from urinary tract infections, respiratory tract conditions like pneumonia, acute bronchitis, and influenza were also found to be guilty in the study, which involved over 7,000 DVTs. The elevated risk slowly declined from 2 weeks to ‘normal’ levels by one year after the infection.

It doesn’t seem to matter which type of infection, though; the increased risk is due to infection-produced inflammation. Other reports have described an increased risk of DVT after non-infectious inflammatory conditions, like inflammatory bowel disease (Crohn’s disease or ulcerative colitis) and rheumatoid arthritis

One should remember that acute infections are also known to increase the risk of acute cardiovascular events, such as heart attack (myocardial infarction, or MI). So, it seems to make sense to treat infectious conditions vigorously, to limit the ensuing inflammation as far as possible.