Deep vein thrombosis (DVT), a blood clot in the deep veins of the legs, is always going to be a matter of concern. Worryingly however, recent NICE guidelines have highlighted an additional concern for those found to be suffering from the condition – the fact that a DVT might indicate the presence of an undiagnosed cancer.
Each year, some forty-eight out of each 100,000 people in a population suffer from DVT. Many people are aware that DVTs can occur after surgery, leg injury or severe illness and, over the last decade or so, there has been a huge focus in the press of DVT after air travel – the so-called “economy class syndrome”.
The combination of considerable media interest and public awareness, coupled with the fears that DVT seems to strike at anytime and can cause a life-threatening blood clot to the lung (pulmonary embolism) makes DVT a feared diagnosis. The condition can also be very hard to diagnose as it is hidden away.
It is commonly recognised that a sudden painful and swollen leg may be a cause for concern. However DVTs can often present themselves in less dramatic or obvious ways. Many patients with a DVT think they just have cramp in a leg that won’t go away. Others think they have an infection, as the leg is hot and swollen, and seek antibiotics from their family doctor before the diagnosis is made.
For anyone who suspects they have a DVT, it is important to seek advice from an experienced vascular expert as DVTs are impossible to diagnose accurately without the correct tests.
A duplex ultrasound scan performed by a well trained and experienced expert can identify any DVT that is present or give the all-clear – often finding another cause of the condition at the same scan. Many services use a blood test as a screening to see if a DVT is likely and use the results to advise whether treatment is needed until a scan can be arranged. It is important to highlight that until the duplex ultrasound scan is performed, the diagnosis of a DVT cannot be confirmed or refuted.
When a DVT occurs in someone who is fit and healthy and has no obvious cause for a DVT, it has been a common practice for doctors to check the patient for factors in the blood that increase the risk of blood clots – a condition called thrombophilia. However, evidence now shows the risk of an undiagnosed cancer causing the DVT is higher than the risk that the DVT was caused by an undiagnosed thrombophilia.
Studies have shown that in patients over the age of forty, the risk of an undiagnosed cancer being found in patients with a spontaneous (or “unprovoked”) DVT is at least ten per cent. The cancers which are most likely to cause DVTs are breast cancer, lung cancer, bowel cancer and pancreatic cancer.
Guidelines issued by NICE (National Institute of Health and Care Excellence) now concentrate on making sure that if a DVT is found in a person with no known reason to have a DVT and no known cancer, they are to have a full medical examination by their doctor who will also carry out other tests including a chest X-ray, blood tests and urine tests. If the patient is forty or over, the doctor might also consider arranging for a CT scan of abdomen and pelvis, and a mammogram if the patient is female.
Of course in the majority of patients who have a DVT, it is highly likely results will show no underlying cancer. However, as has been found over the years, certain cancers have better outcomes if found and treated early, and so correct diagnosis and investigation of a patient might mean that having a DVT is actually blessing in disguise rather than something to fear.