Deep Venous Thrombosis is an important condition; pain and swelling are troublesome and long term damage to the venous circulation is possible. Behind every doctors concern about possible DVT, lies a bigger worry. What if DVT goes on to cause a Pulmonary Embolism? PE gets a bad press: the ones we know about can cause bad breathlessness, haemoptysis and even sudden death. However, increasingly sensitive tests show more, and even more minor, PEs than we could ever know about before. This raises a new question; are we over diagnosing emboli? Perhaps it is part of the lungs job to filter out stuff, including small non-significant clots?
So a pain in the calf can cause doctors quite lot of worry.
This uncertainty was to the fore when Brian B arrived with pain his left calf. He was not sure how it happened, perhaps a rugby injury. He smokes 15 a day, and has just returned from a weekend rugby trip to France (via long train journey). He saw the rugby club doctor ui France who did a D Dimer, which was slightly raised at 350 (normal D-dimer result is less than 250 ng/mL DDU) He didn’t discuss the result much because Brian wanted to get home. Asked about his concerns Brian said “my grandma has just had a lung clot and she is very ill. Could this be a clot in my leg?
Examination showed normal pulse BP and O2 SATS, chest normal. His leg was mildly tender, but there was no actual swelling. While a senior clinician might use a “gestalt” also known as a hunch or a heuristic to say “mmmm DVT pretty unlikely” it is hard to ignore an abnormal result when you have one. So what to do next? Can we still be reassuring? This type of WDYDWYDK is an example of a problem in the ANALYSING QUADRANT. The diagnosis is the issue and at present there is not network group or team involved. So what can the clinician do in these confusing circumstances?
A dysfunctional way out would be to simply send the patient away…to the Accident and Emergency department for Doppler’s to the calf, and maybe even imaging to “rule out” a PE,. This would certainly move the problem away from the GP consulting room yet may expose the patient to radiation, further tests and definitely a lot of inconvenience and worry, even if all turns out to be normal.
So how good is the clinicians “hunch”, that all is well? We can back this up by using appropriate scoring tests…in the age of google they do not have to be committed to memory, the ones relevant here are the wells scorehttp://www.mdcalc.com/wells-criteria-for-dvt/ and the PERC score (Pulmonary embolism Rule out Criteria) http://www.mdcalc.com/perc-rule-for-pulmonary-embolism/ both of which turn out to be normal ie Zero. So he probably did not need that D dimer in the first place.
Does this matter? Well, taking a more considered “worked out” view could save the unnecessary cost of a D-dimer test, prevent further unnecessary imaging and thus decrease radiation exposure from CTPA/CT venography. Furthermore, avoiding referral allows care to be given more quickly to others in the “queue” who may be in greater need. Referring could divert our focus too far in the direction of “ruling in or out a DVT” when there are other causes to consider. In this particular situation the possible causes of a raised D Dimer may related to his smoking or a recent influenza attack, thus it may be just as important to check his chest carefully for infection as it is to check for PE.
Decision scores and rules can be tedious and tick boxy at times; however, applied judiciously they can be a great help in a “what do you do when you do not know what to do” situation.