Peripheral Oedema

Question 1

According to Starling’a Law, oedema is the result of 3 basic pathological processes…

Answer 1

1. Increased hydrostatic pressure
2. Increased membrane permeability
3. Reduced IV oncotic pressure (Starling’s law specificall refers to protein oncotic pressure, but the effect is equally seen with other osmotically active particles such as sodium)

Question 2

List the (4) normal physiological causes of peripheral oedema

Answer 2

Smaller degrees of normal physiological dependent limb oedema can occur as a result of:

● Prolonged standing or sitting (in aircraft)

● Hot weather

● Exposure to high altitude.

● Drugs:

♥	Calcium channel blockers, (vasodilation). 

♥	Contraceptive pill, (fluid retention)

♥	NSAIDs, (salt and water retention)

Question 3

List the pathological physiological causes (12) of peripheral oedema

Answer 3

1. Congestive cardiac failure
2. Protein losing enteropathies
3. Renal disease:

● This may be due to excessive salt and water retention or in particular the nephrotic syndrome where protein is lost through damaged glomeruli.

4. Chronic Liver disease:

● Reduced albumin levels, as well and secondary hyper-aldosteronism leading to sodium and water retention.

5. Lymphoedema:

● The major causes of lymphedema in adults in first world countries are axillary lymph node dissection in patients with breast cancer and axillary or inguinal lymph node dissection in patients with melanoma.

● The most common cause worldwide however is filariasis.

● Damage from radiotherapy.

6. Malignant infiltration
7. Pre-eclampsia/ eclampsia
8. Venous insufficiency:

● This refers to intrinsic local disease of the venous system. Most commonly this will be due to varicose veins, (but also scarring from recurrent and/ or incompletely resolves DVTs) seen most commonly in the legs.

9. Myxedema
10. Nutritional:

● Thiamine (vitamin B1) deficiency; or Wet beri beri, (essentially a B1 deficient cardiac failure)

11. Drugs:Predominantly:

● NSAIDs and steroids, (mainly from sodium and water retention).

● Direct vasodilators, (classically calcium channel blockers).

12. Idiopathic, (a diagnosis of exclusion).

Question 4

Clinical assessment: How does peripheral oedema develop (in what order does it affect particular areas of the body?)

Answer 4

Clinical peripheral oedema can develop progressively as follows:

● Periorbital oedema, in early stages this is often more apparent in the morning.

● Oedema in the hands may first be noticed by tightness of rings

● Dependent limb and sacral edema (pitting or non-pitting)

♥ Unilateral pitting leg oedema strongly suggests DVT

● Oedema up to the genitalia and lower abdomen

● Severe generalized edema throughout the body known as anasarca.

● Ultimately pleural effusions and ascites

Question 5

Clinical assessment: Compare pitting and non-pitting oedema

Answer 5

Pitting edema refers to oedema which “pits” when compressed, (for at least 5 seconds), and then remains indented or only very slowly refills, whereas non-pitting oedema is oedema that does not pit on compression.

Generally speaking, pitting oedema may not be clinically detectable until there is a 10-15% increase in body weight.

As a general rule non-pitting oedema (“Stemmer’s sign”) is caused by lymphoedema or myxedema (hypothyroidism) or localized allergic reactions, and all other causes result in pitting edema.

Question 6

Ix: blood tests?

Answer 6

Blood tests:

1. FBE
2. CRP
3. U&Es/ glucose● Renal impairment
4. LFTs● Evidence of liver disease● Check albumin level in particular

Other more specialized tests are done as clinically indicated:

5. TFTs:● Hypothyroidism

Question 7

Ix: Urinalysis

Answer 7

● FWT (protein, blood, nitrites, leucocyte esterase):

♥ In particular for proteinuria, which if very heavy suggests nephrotic syndrome, (see separate guidelines).

● Microscopy:

♥ For casts which indicates glomerular disease

Question 8

Ix: ECG

Answer 8

This should be done when cardiac failure is the suspected cause of the edema.

Question 9

Ix: imaging

Answer 9

CXR:

This may show indications of congestive cardiac failure:

● Cardiomegaly

● Pulmonary congestion.

Echocardiogram:

This should be done when cardiac failure is the suspected cause of the edema.

CT scan/ MRI Scan:

This may be done when obstructive lesions of the abdomen and/or pelvis are suspected.

Distinguishing lymphoedema from other types of oedema can be difficult, especially early on in a disease process. A characteristic honeycomb pattern in the subcutaneous tissues may also help to distinguish lymphoedema from other oedemas when there is diagnostic uncertainty. MRI is superior to CT in this regard. 4

Lymphogram:

This is a nuclear radiology technique that can be done to directly visualize the lymphatic system.

Question 10

Generally describe rationale for management

Answer 10

Management is directed primarily at the underlying cause, and with careful use of diuretic agents in selected cases.

Question 11

Discuss the use of diuretics in peripheral oedema and when should caution/avoided?

Answer 11

There should be caution in treating oedema with diuretics when the diagnosis is unknown. These can be either ineffective or positively detrimental in some disease processes that lead to generalized edema (such as preeclampsia).

Diuretics should be used with caution or avoided in patients with edema due to venous insufficiency, lymphatic obstruction, or malignant ascites, since the edema fluid cannot be mobilized after the diuretic-induced reduction in plasma volume.