Red Flag Symptoms - Swollen calf

It is important to find out if the symptom is acute or chronic, says Dr Mehul Mathukia.

The most acutely sinister cause for a swollen calf is a DVT (Photograph: SPL)
The most acutely sinister cause for a swollen calf is a DVT (Photograph: SPL)

Calf swelling can be unilateral or bilateral. The most acutely sinister cause for this symptom is a deep-vein thrombosis (DVT) and most red flags in this article would relate to excluding this potentially dangerous condition.

There are many causes for calf swelling. In exploring this condition, it is important to establish if the calf swelling is unilateral or bilateral. Also, one should find out whether the symptom is acute or chronic.

There may be a history of trauma, and this may guide you towards a possible fracture, ruptured muscle or potential compartment syndrome. A history of a chronic medical condition, such as diabetes or congestive heart failure, may predispose to conditions such as cellulitis.

Risk factors for a DVT include smoking, taking the oral contraceptive pill, obesity, thrombophilic states such as factor V Leiden as well as pregnancy and increasing age.

The patient may not be able to bear weight or may be walking with a limp. The patient may be tachycardic, and possibly febrile. Examination of the calf may show features of inflammation including redness, warmth, tenderness and enlargement compared with the contralateral calf at a fixed point.

Homan's test demonstrates pain on dorsiflexion of the foot, but this should be done with caution as it may trigger fragmentation of a clot.

The peripheral pulses should be assessed, as dorsalis pedis pulse may be absent in a DVT, but may also be suggestive of compartment syndrome.

Calf swelling may be bilateral and pitting may be seen, suggestive of periperhal oedema secondary to conditions such as congestive heart failure.


These will be directly guided by the clinician's assessment of the calf swelling. Wells score can identify the risk of DVT and a score greater than one should warrant further investigations.

These include blood tests such as a d-dimer and FBC, clotting, LFT and U&Es. Doppler ultrasound should also be considered.

If other conditions are suspected, one may consider tests such as a limb X-ray, knee ultrasound and even MRI imaging. If a DVT is suspected, urgent referral to the nearest secondary care centre is vital.

  • Dr Mathukia is a GP principal in Ilford, Essex
Possible causes
  • Calf trauma
  • DVT
  • Thrombophlebitis
  • Cellulitis
  • Ruptured gastrocnemius muscle
  • Bone tumour
  • Ruptured Baker's cyst
  • Fracture
  • Compartment syndrome

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