All that follows is from the above resource.
We have seen our esteemed guests, and they are us! Paul Williams (@PaulNWilliamz) leads the discussion with Matt Watto (@DoctorWatto) and Beth “Garbs” Garbitelli (@bethgarbitelli) on the evaluation and management of common causes of edema.
- The pathophysiology behind edema is an imbalance between oncotic pressure and hydrostatic pressure within the venous system.
- Chronic venous insufficiency* is the most common cause of chronic lower extremity edema, especially in older patients.
- Again, bilateral lower extremity cellulitis is extremely uncommon.
- Edema may be a sign cardiopulmonary, renal, hepatic, or thyroid dysfunction – so look at the patient in front of you and evaluate for risk factors.
- Lymphedema results from impairment of lymphatic return, and can sometimes be distinguished from other causes of edema by the Stemmer sign.
- Medications are a common cause of lower extremity edema – don’t forget about the gabapentinoids!
- May-Thurner syndrome is caused by anatomical compression of the left iliac vein, and can result in unilateral edema or recurrent deep vein thrombosis.
- Acute edema can be caused by deep vein thrombosis, cellulitis, or ruptured popliteal cyst, all of which may be difficult to differentiate from each other.
- The physical examination should be directed at finding underlying systemic causes of lower extremity edema.
- Management of edema usually includes compression, elevation, and avoidance of exacerbating medications.
Lower Extremity Edema Notes
Edema – Pathophysiology
Generally speaking, venous circulation maintains a balance between hydrostatic pressure and oncotic pressure. Edema can result from perturbations in these forces (Trayes et al 2013).
- Increased hydrostatic pressure
- Venous hypertension from right-sided heart failure, venous insufficiency, constrictive pericarditis, etc.
- Endoluminal obstruction (e.g. venous thrombosis, popliteal cyst, etc.)
- Decreased oncotic pressure
- Low-protein states like nephrotic syndrome, hepatic failure, protein-energy malnutrition
- Capillary dilation
- Vasodilation from warmer weather
- Inflammatory states such as burns or cellulitis
Recall that venous return is largely a passive process and requires functional valves and muscle contraction. Defects in either of these can result in diminished venous return, increased venous pressure, and resultant edema.
Determining the Cause – Chronic Edema
Chronic venous insufficiency
- Ultrasonography from emedicine.medscape.com
- “Duplex ultrasonography is the study of choice for the evaluation of venous insufficiency syndromes.”
- Probably the most common cause (Beebe-Dimmer et al 2005)
- Prevalence increases with age
- More common in patients with obesity
- Represents a spectrum of disease from painless edema to chronic ulcerative disease
- A gentle reminder: bilateral cellulitis of the lower extremities is uncommon
- Evaluate patients for signs and symptoms of heart failure and untreated or undiagnosed obstructive sleep apnea
- Evaluate for risk factors for nephrotic syndrome
- Don’t forget to look for periorbital edema (and don’t forget Tony Breu’s amazing Tweetorial)
- Evaluate for stigmata of chronic liver disease
- Pretibial myxedema (thyroid dermopathy)
- Rare manifestation of Graves’ disease
- Typically bilateral and non-pitting
- Hypothyroidism can also lead to non-pitting edema
- Can be idiopathic or secondary
- Secondary lymphedema can be caused by surgery or radiation
- Filariasis most common cause worldwide (Green 2015)
- Caused by an impediment of lymphatic return
- Chronic leakage of proteins leads to inflammation and ultimately fibrosis
- Results in thickening of the skin and tissues
- Pathologic accumulation of adipose tissue in the lower extremities
- Classically spares the feet
- Calcium channel blockers
- Dihydropyridines more than non-dihydropyridines
- Effect tends to be dose-dependent
- Edema from calcium channel blockers not effectively treated by diuretics
- Angiotensin-receptor blockers or ACE-inhibitors are more effective at mitigating this
- Mechanism thought to be due to vasodilatory effects and decreased myogenic tone (Largeau et al 2021)
- Oral contraceptives
- Cause of unilateral lower extremity edema
- Female predominant
- Compression of the left iliac vein by the right iliac artery
- Can predispose to left lower extremity DVT
- Any condition that affects calf muscle strength can lead to edema (Ratchford and Evans 2017)
- Includes stroke, multiple sclerosis, and even lumbar radiculopathy
Determining the Cause – Acute Edema
Deep vein thrombosis
- Likelihood can be predicted by calculating Wells score
- Generally requires ultrasonography for diagnosis
- Clinically difficult to differentiate from DVT
Ruptured popliteal cyst
- Classically presents with ecchymosis around the ankle
- Again, may be clinically challenging to differentiate from other causes
- Ultrasonography usually required to make the diagnosis
Edema – The Workup
- Assess for symptoms of cardiac disease
- Assess for JVD
- Pitting edema can be extensive and extend proximally to the sacrum in heart failure
- Evaluate for pitting versus non-pitting
- Non-pitting edema seen in lymphedema
- Check for Stemmer’s sign to evaluate for lymphedema
- Inability to pinch the skin at the base of the toes due to skin changes
- Evaluate for superimposed cellulitis if chronic changes of venous insufficiency are seen
- Reasonable to check urine protein-creatinine ratio
- In most patients, could consider comprehensive metabolic panel to evaluate albumin and electrolyte abnormalities
- TSH often checked to rule out thyroid causes
- Additional testing, such as urinalysis, complete blood count, BNP, or D-dimer, could be considered depending on patient history and risk factors
- Venous ultrasound studies should be ordered if there is suspicion for DVT
- Consider a transthoracic echocardiogram in patients with cardiopulmonary symptoms
- Polysomnography is appropriate for patients for whom there is high suspicion for sleep apnea
- Abdominopelvic imaging may be appropriate when the cause is not fully elucidated and there is suspicion for malignancy or other compressive or obstructive etiology
Edema – Management
- Stop exacerbating medications, if possible
- Compression stockings are generally helpful, especially for chronic venous insufficiency
- Avoid if arterial insufficiency is suspected
- Elevate the legs when possible
- Diuretics may not be helpful in the absence of volume overload
- They are not effective at mitigating edema caused by calcium channel blockers
- Patient education and reassurance are an important component of management
- There is some evidence for horse chestnut seed extract in the short-term treatment of chronic venous insufficiency (Pittler and Ernst 2012)
- Best managed by a multidisciplinary team
- Usually includes physical therapy and vascular surgery teams
- Patients typically undergo complex decongestive physiotherapy
- Primary care provider role is to help provide meticulous skin care and ensure care coordination