Formerly called hydropsy or dropsy, edema is the abnormal accumulation of fluid inside the interstitium and is clinically explained as being a swelling. Interstitium refers to body cavities (one or more) or locations underneath the skin. Generally, the balance of homeostasis is what determines the interstitial fluid amount. Impaired removal or increased secretion of this fluid is what results in edema.
There are many types of edema and edema grading generally depend on the depth and duration of the dent.
Classification of Edema
| Edema Types | Description |
|---|---|
| Cutaneous edema |
It occurs when a small area gets pressurized and the indentation continues even after the pressure is removed. |
| Peripheral pitting edema |
It is a common type which comes about when there is water retention and can be caused by various conditions like heart failure, pregnancy or diseases. |
| Non-pitting edema |
It is where indentation is not persistent and is associated with conditions like myxedema, lipedema ad lymphedema. |
Edema Grading
Edema generally accounts for ten to thirty percent of bodyweight. However, in severe kwashiorkor cases, the proportion can even reach 50%.
Pitting edema is graded on a scale of one to four. The scaling depends on both the “pit” leaves and depth and how long the pit will remain.
Grading Method 1: Dent Depth and Duration
| Grade | Definition |
|---|---|
| 1+ |
2mm or less: slight pitting, no visible distortion, disappears rapidly. |
| 2+ |
2-4mm indent: somewhat deeper pit, no readably detectable distortion, disappears in 10-25 seconds. |
| 3+ |
4-6mm: pit is noticeably deep. May last more than a minute. Dependent extremity looks swollen and fuller. |
| 4+ |
6-8mm: pit is very deep. Lasts for 2-5 minutes. Dependent extremity is grossly distorted. |
Source: Guelph General Hospital Congestive Heart Failure Pathway
Grading Method 2: Dent Depth and Rebound Time
| Grade | Definition |
|---|---|
| 1+ |
Three is a barely detectable 2mm depression. Immediate rebound |
| 2+ |
There is a 4mm deep pit. A few seconds to rebound. |
| 3+ |
There is a 6mm deep pit. 10-12 seconds to rebound. |
| 4+ |
There is an 8mm deep pit (very deep). >20 seconds to rebound. |
Source: Hogan, M (2007) Medical-Surgical Nursing (2nd ed.). Salt Lake City: Prentice Hall
Grading Method 3: Overall Severity of Edema
There are three grades of bilateral pitting oedema, and when it is not present, the grade is “absent”. Bilateral pitting oedema grades are classified using plus signs:
| Grade | Definition |
|---|---|
| 1+ |
Mild: Both ankles/feet |
| 2+ |
Moderate: Both feet, hands, lower arms and lower legs |
| 3+ |
Severe: Generalized bilateral pitting oedema, which includes both legs, arms, feet and face. |
Source: http://www.unicef.org/nutrition/training/3.1/20.html
Watch a video for pitting edema: