Edema Grading and Causes

Overview

This lecture covers the grading of pitting edema, its causes, and how to differentiate it from non-pitting edema.

Edema is swelling caused by excess fluid in tissues.
Not all edema is pitting; causes differ by type.
Pitting edema is usually caused by increased hydrostatic pressure or decreased oncotic (protein) pressure in blood.
Non-pitting edema may result from lymphatic obstruction.

Pitting edema is typically graded on a scale from 0 (no edema) to 4+ (severe edema).
0 or "No Pitting": No indentation after applying pressure.
1+ Pitting Edema: Slight indentation (about 2 mm) that disappears almost immediately after pressure is removed.
2+ Pitting Edema: Mild indentation (about 4 mm) that resolves in 10–25 seconds.
3+ Pitting Edema: Moderate indentation (4–6 mm) lasting over one minute; edema is visible to the eye.
4+ Pitting Edema: Severe indentation (≥6 mm) lasting a prolonged period, with marked, obvious swelling and a "Play-Doh"-like texture.

1+ pitting edema can be subtle and easier to detect during peripheral pulse checks.
Severity and duration of indentation help distinguish levels of pitting edema.

Edema — swelling from excess fluid in body tissues.
Pitting Edema — indentation remains in the skin after pressure is applied.
Non-Pitting Edema — swelling without indentation after pressure.
Hydrostatic Pressure — the force exerted by fluid, contributing to fluid leakage into tissues.
Oncotic Pressure — pressure from blood proteins that keeps fluid in the bloodstream.
Lymphatic Obstruction — blockage of lymph flow causing non-pitting edema.