Questions about a swollen leg.

NOTE: These blog posts are written from the perspective of a GP colleague who still seems to accumulate a list of unanswered questions at the end of each day in practice.  Each post describes how I went about trying to answer the specific questions.  These posts are not intended to be used for specific clinical guidance but hopefully provide links to some useful resources which the registrar can explore for themselves.  

General Practice is not just about diagnosis or emergency management, even though these might be the easiest processes to test in exams.  It is about “choosing wisely” when ordering tests, how to apply algorithms and guidelines to the individual patient before you, providing patient education, how to manage the uncertainty of persisting symptoms with no clear diagnosis, considering the broader implications of management for this patient (including costs) and taking opportunities for primary and secondary prevention even though we may never know how this affects outcomes for the individual patient.

I was on holiday recently in a country where I don’t speak the language.  One of the people in our tour group mentioned having a swollen leg which they put down to being on their feet a lot.  This is obviously a different situation from when a patient walks into your surgery but let me phrase my thoughts in exam format (with details changed to de-identify the person) with some tangential options.

Some questions
In terms of diagnosis, you might think in terms of the MOST LIKELY diagnosis versus the MOST IMPORTANT diagnosis.  What is the most important diagnosis?  I was thinking DVT with its attendant risk of a PE.

Mrs Smithson, a retired 75 year old, notices a unilateral swollen leg after a long haul flight.  It’s quite tense and obviously larger than the other one with very slight warmth anteriorly, a negative Homans sign, no tenderness, and discomfort rather than pain.   She had a joint replacement some months ago and a history of a DVT 5 years ago after a hip replacement.  Just for interest, what would you advise this fellow traveller from the following options?  Choose up to five.

  1. Try to see a local doctor immediately
  2. Take the anti-coagulant (NOAC) that her husband happens to have with him
  3. Attend the ED in the next big town you are visiting in order to have some investigations
  4. A negative ultrasound would be sufficient to rule out a DVT
  5. Check on her travel insurance
  6. Take the antibiotics offered by another traveller (in case it is cellulitis)
  7. If the US is negative a D Dimer is recommended
  8. Keep wearing the support stockings she wore on the plane
  9. Rest with the leg up rather than going on excursions
  10. Organise earlier return home
  11. If US is negative and D Dimer not done then she should have repeat US on return in a week

All these options raise discussion points. Of course, this isn’t a typical situation at all and is likely to involve delays in investigation and different protocols in other hospital systems so I’ll move onto more general principles that apply at home.  A presentation like this is something GP registrars would be very familiar with from their ED terms and they are often more up to date with guidelines than supervisors.  However, GP presentations can be different and management may also depend on context (urban or remote for instance).

Utilising guidelines
This situation did indeed make me refresh my mind re the Wells Score on which she scored 3 (likely DVT) just on the history I knew of.   The criteria also remind that no decision rule should trump clinical gestalt.   The NICE guidelines in the UK also utilise the Wells Score – and note there are several versions of the Wells Score.

To put things in context the following is an extract (This also outlines treatment)

  • Clinical diagnosis is unreliable. Among adults in primary care settings who have signs and/or symptoms of DVT, only 29% had USS proven DVT.
  • To better evaluate the clinical probability of DVT, validated scoring systems have been developed.
    • If the pre-test probability is LOW (DVT unlikely) then a D-dimer test should be performed. If negative, a DVT can be reliably excluded. If positive, further imaging is required.
    • If the pre-test probability is HIGH (DVT likely) then imaging should be performed. A normal scan does not exclude DVT so a D-dimer should be performed after. If this is negative, then a DVT can be excluded. If it is positive, imaging should be repeated within 1 week.
  • In recent years clinical practice has shifted to favour using NOAC over LMWH for treatment of DVT. Although there has been some debate over the value of treating isolated distal deep vein thrombosis (IDDVT), as opposed to serial imaging in 2 weeks, the most recent advice is to commence anticoagulation if there are no contraindications. Cited benefits include prevention of PE, proximal extension and post-thrombotic syndrome, as well as relief of symptoms

Note there are contraindications, precautions and baseline tests relevant to the various treatment regimes.

A different exam question might be “what is the most important investigation to do at this point?” and the Wells criteria state that all DVT-likely patients should receive a diagnostic ultrasound.  The next question might be about the place of D Dimer in such instances. This might depend on availability and has certain caveats.  Of course, a very relevant question to be asking yourself is about the sensitivity and specificity of the various diagnostic tests (and how you relay this to a patient)  A useful but slightly older AFP article that summarises the issues is Deep Vein Thrombosis: Risks and Diagnosis.  This and the NICE guidelines advise that if testing is delayed and clinical suspicion is high (NICE gives timeframes) then empirical  anticoagulation should be started if there are no contraindications)

Differential diagnoses
An additional, relevant question would be about the differential diagnoses and if any of these are more likely.  Other conditions present with similar symptoms to DVTs including muscle strain, phlebitis, cellulitis, or ruptured Bakers cyst.  If the whole leg is swollen and the scan is negative consider pelvic vein thrombosis requiring other imaging (CT/MRI or venography).

Diagnostic uncertainty
In general practice, you are just as likely to see the patient who has had DVT excluded in ED but presents to you with the question “so what is causing the swelling?”  Swollen ankles can be one of those geriatric syndromes where more than one cause is contributing to a presenting symptom (especially if bilateral) and you may need to consider multiple systems (venous, lymph, cardiac, mechanical obstruction, renal, liver and medications) as causes can co-exist or be superimposed.  It is reasonable to investigate the likely causes and advise of useful symptomatic measures.

In my experience, some patients complain of swelling after TKR for longer than the weeks to three months that they are advised.   It is difficult to know what the specific causes are but these patients need support. It is discouraging for them to experience this after having high expectations.  I have also had a couple of patients with Complex Regional Pain Syndrome post operatively where the pain was more prominent.

We all think about long-haul flights as a cause but DVTs are more likely to occur in other circumstances. There can be more than one contributing cause.  Early in my career, I had a couple of patients who had DVTs after lengthy car trips while on HRT (when it was being prescribed more often).  It is amazing to me that more patients in Residential Aged Care do not present with symptoms given their frequent immobility and other risk factors.  Surgery is a high risk (and the risk persists for weeks) and, as a patient, I once had gynaecological surgery where staff forgot to apply the appropriate stockings.  Registrars are likely to have younger patients in their practice who are travelling and taking OCPs.  Some may be known to have other risk factors such as Factor V Leiden.

In terms of prevention see this recent Cochrane review which concluded “High-quality evidence shows that airline passengers wearing compression stockings develop less symptomless DVT”.  I do advise my patients about this and I wear them myself.

Secondary prevention is an area that GPs should not overlook.

Studies have found a high percentage of patients with DVT (especially proximal) develop some changes in chronic venous insufficiency and post-thrombotic syndrome which increases the risk of ulcers later on. The incidence of post-thrombotic syndrome can be reduced by wearing below knee graduated compression stockings.

Relevant blood tests for coagulation disorders should be done for idiopathic DVT as some indicate a risk for recurrent DVT.  Some of the above links give more details on this and other relevant issues – so you can update yourself on relevant clinical issues.

About our guest blogger
Dr Cathy Regan has worked in GP vocational training for more than 20 years.

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