Approach to lower limb edema: Clinical sciences

Edema is an abnormal accumulation of interstitial fluid in the tissues. This occurs due to an imbalance between the hydrostatic and oncotic forces at the level of the capillaries. The lower limbs are especially prone to the development of edema because of gravity.

Based on location and symmetry, lower limb edema can be classified as unilateral and bilateral. Unilateral lower limb edema is usually caused by a pathological process in the limb itself, such as DVT or compartment syndrome, while bilateral lower limb edema is usually due to systemic causes like heart, liver, and kidney failure. A more severe type of edema is anasarca, where the whole body develops generalized edema, and can be caused by things like malnutrition, as well as cirrhosis, nephrotic syndrome, or even burns.

When approaching a patient with lower limb edema, you should first perform an ABCDE assessment to determine if your patient is unstable or stable. If your patient is unstable, you should first stabilize their airway, breathing, and circulation before trying to identify the cause. This means that you might need to intubate the patient and establish IV access before continuing with your assessment.

On the other hand, if the patient is stable, the next step is to obtain a focused history and physical examination. Your history should explore if one or both lower limbs are affected, time span over which edema developed, associated symptoms such as pain or shortness of breath, known acute or chronic medical conditions, and a list of medications. Your physical exam should focus on describing the characteristics of the edema, like location, symmetry, and whether it’s pitting or non-pitting, as well as other features like skin discoloration and the quality of the pulse in the affected limbs.

First, let’s start with conditions that cause unilateral edema. Unilateral edema generally affects a single limb and can be acute, that is developing over a period of 72 hours or less, or it might be chronic where it takes longer than 72 hours to develop. You’ll want to rule out potentially life and limb-threatening conditions associated with unilateral edema first.