This is from Jarvis Physical Examination & Health Assessment,
In the Chapter "Peripheral Vascular System and Lymphatic System"
If pitting edema is present, grade it on the following scale:
1+ Mild pitting, slight indentation, no perceptible swelling of the leg
2+ Moderate pitting, indentation subsides rapidly
3+ Deep pitting, indentation remains for a short time, leg looks swollen
4+ Very deep pitting, indentation lasts a long time, leg is very swollen
This scale is subjective and qualitative. The amount of pressure used is arbitrary, as is the judgment of the depth and rate of pitting. Clinicians need a standard quantified scale in order to ensure consistent clinical measurements and management. Many classify the edema by measuring the depth of the pitting in centimeters (1+ = 1 cm, 2+ = 2 cm, etc.) (Welsh, Arxouman, and Holm, 1996).
Some measure with a millimeter scale, others by an increase in weight, still others try to quantify the rate of time the pitting remains after release of pressure. Check with your institution to determine a consistently used scale.