Key distinguishing features of the most common diagnoses
|Cellulitis||Swollen Ankles||Muscular||Baker’s Cyst||DVT|
|Previous Swelling Behind Knee||No||No||No||Yes||No|
Likely:None (unless sent to hospital).
Possible:FBC, ESR/CRP and other investigations for swollen ankles (see also 'swollen ankles' section); usually in hospital – D-dimer, ultrasound, venography.
- FBC, ESR/CRP: Elevated white cell count and ESR/CRP in cellulitis.
- D-dimer: Raised level suggests DVT but is not conclusive.
- Ultrasound: May help diagnose DVT and useful in confirming ruptured Baker’s cyst as the cause. Venography necessary to confirm DVT in some cases.
- The swelling resulting from a muscle rupture can be impressive – but a typical history with pain (described as ‘like being shot in the calf ’) preceding the swelling should clinch the correct diagnosis.
- Varicose eczema is often misdiagnosed as cellulitis. Clues are that it is commonly bilateral, itches more than hurts and is not accompanied by fever. To complicate matters, varicose eczema can become infected, causing cellulitis.
- Anxiety about possible DVT may cloud the presentation – careful questioning may reveal that swelling is, in fact, long-standing and/or bilateral, making DVT very unlikely.
- Patients with unexplained DVT are three to four times more likely than controls to have an underlying malignancy – so, once the DVT has been dealt with, consider appropriate investigation.
- In high-risk patients – such as those who have just returned from a long haul flight – your index of suspicion for DVT should be raised.
- When the history suggests muscular rupture, ensure that the Achilles tendon is intact.