Edema / Oedema; Types, Causes, Lower Extremity Edema

Edema / Oedema; Types, Causes, Lower Extremity Edema

Edema also spelled oedema or edema, is an abnormal accumulation of fluid in the interstitium, located beneath the skin and in the cavities of the body, which can cause severe pain. Clinically, edema manifests as swelling. The amount of interstitial fluid is determined by the balance of fluid homeostasis; and the increased secretion of fluid into the interstitium. The word is from meaning “swelling. An edema will occur in specific organs as part of inflammations, tendonitis or pancreatitis, for instance.
Certain organs develop edema through tissue-specific mechanisms. Examples of edema in specific organs

Classification according to the organ position

  • Cerebral edema is extracellular fluid accumulation in the brain. It can occur in toxic or abnormal metabolic states and conditions such as systemic lupus or reduced oxygen at high altitudes. It causes drowsiness or loss of consciousness, leading to brain herniation and death.
  • Pulmonary edema occurs when the pressure in blood vessels in the lung is raised because of obstruction to the removal of blood via the pulmonary veins. This is usually due to failure of the left ventricle of the heart. It can also occur in altitude sickness or on inhalation of toxic chemicals. Pulmonary edema produces shortness of breath. Pleural effusions may occur when fluid also accumulates in the pleural cavity.
  • Edema may also be found in the corner of the eye with glaucoma, severe conjunctivitis or keratitis or after surgery. Sufferers may perceive colored haloes around bright lights.
  • Edema surrounding the eyes is called periorbital edema or eye puffiness. The periorbital tissues are most noticeably swollen immediately after waking, perhaps as a result of the gravitational redistribution of fluid in the horizontal position.
  • Common appearances of cutaneous edema are observed with mosquito bites, spider bites, bee stings (wheal and flare), and skin contact with certain plants such as Poison Ivy or Western Poison Oak, the latter of which are termed contact dermatitides.
  • Another cutaneous form of edema is myxedema, which is caused by increased deposition of connective tissue. In myxedema (and a variety of other rarer conditions) edema is caused by an increased tendency of the tissue to hold water within its extracellular space. In myxedema, this is because of an increase in hydrophilic carbohydrate-rich molecules (perhaps mostly hyaluronan) deposited in the tissue matrix. Edema forms more easily independent areas in the elderly (sitting in chairs at home or on airplanes) and this is not well understood. Estrogens alter body weight in part through changes in tissue water content. There may be a variety of poorly understood situations in which transfer of water from tissue matrix to lymphatics is impaired because of changes in the hydrophilicity of the tissue or failure of the ‘wicking’ function of terminal lymphatic capillaries.
  • In lymphedema abnormal removal of interstitial fluid is caused by the failure of the lymphatic system. This may be due to obstruction from, for example, pressure from cancer or enlarged lymph nodes, destruction of lymph vessels by radiotherapy, or infiltration of the lymphatics by infection (such as elephantiasis). It is most commonly due to a failure of the pumping action of muscles due to immobility, most strikingly in conditions such as multiple sclerosis, or paraplegia. It has been suggested that the edema that occurs in some people following the use of aspirin-like cyclo-oxygenase inhibitors such as ibuprofen or indomethacin may be due to inhibition of lymph heart action.
  • Hydrops fetalis is a condition of the fetus characterized by an accumulation of fluid, or edema, in at least two fetal compartments.
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Lower Extremity Edema

51-year-old male with a history of HTN, DM and chronic alcohol abuse presenting with lower extremity swelling. He notes one month of progressive, bilateral lower extremity swelling, in the past two weeks associated with increasing pain and redness and is now no longer able to ambulate due to pain. He denies fevers/chills, chest pain or shortness of breath. He also denies orthopnea and paroxysmal nocturnal dyspnea. He states that he has not had these symptoms prior to one month ago. On review of systems, he denies nausea/vomiting, abdominal pain, and changes in bowel or urinary habits. He has a history of GI bleeding (unknown treatment) but denies hematemesis, hematochezia or melena. He has previously experienced alcohol withdrawal, which manifested as tremors, but no hallucinations or seizures

Types of Edema

  • Peripheral edema –This usually affects the legs, feet, and ankles, but it can also happen in the arms. It could be a sign of problems with your circulatory system, lymph nodes, or kidneys.
  • Pedal edema –This happens when fluid gathers in your feet and lower legs. It’s more common if you’re older or pregnant. It can make it harder to move around in part because you may not have as much feeling in your feet
  • Lymphedema –This swelling in the arms and legs is most often caused by damage to your lymph nodes, tissues that help filter germs and waste from your body. The damage may be the result of cancer treatments like surgery and radiation. Cancer itself can also block lymph nodes and lead to fluid buildup.
  • Pulmonary edema – When fluid collects in the air sacs in your lungs, you have pulmonary edema. That makes it hard for you to breathe, and it’s worse when you lie down. You may have a fast heartbeat, feel suffocated, and cough up a foamy spittle, sometimes with blood.
  • Cerebral edema –This is a very serious condition in which fluid builds up in the brain. It can happen if you hit your head hard if a blood vessel gets blocked or bursts or you have a tumor or an allergic reaction.
  • Macular edema – This happens when fluid builds up in a part of your eye called the macula, which is in the center of the retina, the light-sensitive tissue at the back of the eye. It happens when damaged blood vessels in the retina leak fluid into the area.
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Physical Exam

VS: T 37.6 HR 86 RR 16 BP 128/84 O2 99% RA
Gen: Adult, non-obese male, lying in bed. Tremors noted in upper extremities.
HEENT: PERRL, EOMI, no scleral icterus. Mucous membranes moist.
CV: RRR, normal S1/S2, no additional heart sounds, JVP 3cm above sternal angle at 30°.
Lungs: CTAB, no crackles.
Abd: Soft, non-distended, with normoactive bowel sounds. Liver edge palpated 1cm below costal margin at mid-clavicular line, non-tender. No rebound/guarding.
Ext: Warm, well-perfused with 2+ distal pulses (PT, DP). 3+ pitting edema symmetric in bilateral lower extremities to knee. Erythema and warmth bilaterally extending from ankles to mid-shin. Mild tenderness to palpation. No pain with passive dorsiflexion. 3x3cm shallow ulceration below medial malleolus on right lower extremity without underlying fluctuance or expression of purulent material. No venous varicosities noted. Decreased sensation to light touch below knee bilaterally.
Rectal: Normal rectal tone, brown stool, guaiac negative.
Neuro: Alert and oriented, CN II-XII intact, gait intact, normal FTN/RAM.


  • CBC: 7.4/13.1/39/180
  • Creatinine: 0.84
  • Albumin: 4.3
  • BNP: 28


Venous Lower Extremity Ultrasound

  1. No DVT.
  2. Pulsatile flow in bilateral EIV (external iliac veins) suggestive of elevated right heart pressure.


51M with HTN, DM, EtOH abuse presenting with lower extremity edema. Chronic bilateral lower extremity edema likely secondary to chronic venous insufficiency perhaps related to OSA given ultrasound findings of pulsatile flow in EIV’s. Doubt systemic cause: no evidence of heart failure on exam and normal BNP, no stigmata of cirrhosis and normal albumin, normal creatinine. Also, no evidence of DVT on ultrasound though bilateral DVT unlikely. Bilateral cellulitis also unlikely as the patient is afebrile without leukocytosis, however the patient was started on antibiotics including ceftriaxone and TMP/SMX given erythema, warmth and tenderness to palpation. The patient received benzodiazepines which eased withdrawal symptoms and he was admitted for continued treatment.

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Mechanisms of Lower Extremity Edema

Mechanisms of Lower Extremity Edema

Differential Diagnosis of Lower Extremity Edema

Differential Diagnosis of Lower Extremity Edema



  • Duration: acute (<72h) vs. chronic
  • Pain: DVT, CRPS, less severe in venous insufficiency
  • Systemic Disease
    • Cardiac: orthopnea, PND
    • Renal: proteinuria
    • Hepatic: jaundice, ascites
  • Malignancy: lymphedema
  • Improvement with elevation/recumbency: venous insufficiency
  • OSA: snoring, daytime somnolence
  • Medications: B-blocker, CCB, hormones, NSAID’s

Physical Exam

  • Distribution: unilateral, bilateral, generalized
  • Quality: pitting, non-pitting
  • TTP: DVT, cellulitis
  • Varicose veins: venous insufficiency
  • Kaposi-Stemmer: inability to pinch dorsum of foot at base of 2nd toe (lymphedema)
  • Systemic Disease
    • Cardiac: JVD, crackles
    • Hepatic: ascites, scleral icterus, spider angiomas
  • Brawny, medial maleolar involvement: venous insufficiency

Key Features Distinguishing Cellulitis

  • Typically unilateral and acute
  • Often with systemic symptoms (fever, leukocytosis)
  • Risk Factors: immunosuppression, previous episodes, DM, PVD

Treatment of Edema

Medications. Many medicines can cause edema, including:

  • NSAIDs (such as ibuprofen and naproxen)
  • Calcium channel blockers
  • Corticosteroids (like prednisone and methylprednisolone)
  • Pioglitazone and rosiglitazone
  • Pramipexole




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