Unilateral Leg Swelling
Differential Overview
❑ Deep vein thrombosis
❑ Venous insufficiency
❑ Calf muscle strain/hematoma
❑ Cellulitis
❑ Superficial thrombophlebitis
❑ Ruptured Baker cyst
❑ Postphlebitic syndrome
❑ Varicose veins
❑ Calf muscle infarction
❑ Lymphatic obstruction
Diagnostic Approach
Classic symptoms of DVT are swelling and pain in the involved leg, but diagnosis based on clinical signs is unreliable. The best strategy is to have a high index of suspicion followed up with diagnostic tests. Clinically important DVT can be effectively ruled out (post-test probability 0.43%) if risk indicators are absent (DVT score 0) and the d-Dimer is negative.
The circumference difference in normals (95% CI) is 1.5 cm between the thighs and 1.7 cm between the calves. Occasionally, bilateral edema with asymmetry may occur. While rarely due to a new deep vein thrombosis, the conditions that cause edema increase the risk of thrombosis. One must be alert for signs of compartment syndrome, especially in the setting of trauma. Early clues include numbness over the foot and distal weakness due to ischemia of muscles within the compartment. The distal pulses are often preserved.
The Ottawa DVT Rule scores 1 point each for: active cancer; paralysis, paresis, or plaster immobilization; recently bedridden .3 days or major surgery within 4 weeks; localized tenderness over the distribution of the deep veins; entire leg swollen; calf circumference 10 cm below tibial tuberosity 3 cm of greater than other calf; pitting edema only in the symptomatic leg; collaterals dilated but not varicose veins. If an alternate diagnosis is as likely or more likely than DVT, subtract 2 points from the total score.
Clinical Findings
Deep vein thrombosis Asymmetric swelling may be the only sign of DVT. Other signs include tenderness over the calf, popliteal space and medial aspect of the thigh, and the presence of dilated “sentinel veins” over the anterior tibia, which do not collapse with leg elevation.
Venous insufficiency The swelling is more chronic and is accompanied by findings such as varicosities and hemosiderin hyperpigmentation over the shin. A stasis ulcer may also develop.
Calf muscle strain/hematoma Strain occurs following vigorous exercise. The muscle body is tender to lateral compression, as opposed to posterior calf compression with DVT. Although there will be no ecchymosis if the hematoma is beneath the muscle fascia, a telltale purple crescent will later appear under the malleolus.
Cellulitis Although thrombophlebitis and Baker cyst can both cause erythema, cellulitis will have sharply demarcated and advancing borders. Fever, chills, lymphangitis, and tender adenopathy in the ipsilateral groin support the diagnosis of cellulitis.
Superficial thrombophlebitis There is superficial erythema and tenderness, usually with a superficial palpable cord.
Ruptured Baker cyst A palpable fluid-filled bursa in the popliteal space can often be felt in patients with knee arthritis. When ruptured and dissected into the calf, it is no longer present, but may be inferred by knee crepitance and/or effusion.
Postphlebitic syndrome This presents as chronic unilateral swelling and aching pain in a leg previously affected by deep vein thrombosis. Acute changes in the degree of swelling make differentiation from a recurrent DVT difficult.
Varicose veins They usually occur with venous valve incompetence, which can be demonstrated by the Trendelenburg test. Raise the leg and occlude the proximal saphenous vein. Have the patient stand, and then release the vein. Immediate filling will be seen with incompetence. Incompetence of the lowest perforators will give a “flare sign” with dilation of the veins over the posterior ankle with calf contraction.
Calf muscle infarction There is usually an embolic source (e.g., atrial fibrillation or aortoiliac atherosclerosis), or bleeding within a compartment due to muscle strain or trauma. The muscle becomes tender, then swollen and tense. Numbness over the foot is an early sign of compartment syndrome, and the distal pulse is preserved until late in the course.
Lymphatic obstruction The edema is chronic and brawny, with little pitting or change with elevation.
Pictures
Book Source Details
- Book Title: Field Guide to Bedside Diagnosis
- Author(s): David S. Smith
- Year of Publication: 2007
- Copyright Details: Field Guide to Bedside Diagnosis, Copyright © 2007 Lippincott Williams & Wilkins.
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Copyright Details: Field Guide to Bedside Diagnosis, Copyright © 2008 Williams & Wilkins.
More About Causes of Leg symptoms
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More About This Book:
Title: Field Guide to Bedside Diagnosis
Authors: David S. Smith
Publisher: Lippincott Williams & Wilkins
Copyright: 2007
ISBN: 0-78178-165-5
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