The persistence of pitting (indentation) in the skin after application of firm pressure is a classic sign of swelling due to increased interstitial fluid in subcutaneous tissues.
Apply firm pressure to swollen area for a 5 seconds. Use finger pads or thumb press tissue against a bony surface (dorsum of foot, tibia, fibula or sacrum). The resultant indentation may remain for some time (minutes).
Test findings (positive & negative):
Pitting oedema manifests when considerable extracelluar fluid has collected (an increase in body weight of over 10% with daily weight fluctuation). This can be due a number of mechanisms: postural (in elderly, immobile patients), local (due to venous obstruction or inflammation) or systemic (generalised oedema due to cardiac, renal, liver or GIT disorders causing fluid overload or hypoproteinaemia). Severity of pitting can be graded from 1 to 4 depending on severity and time to resolution.