A hand-held electronic device designed to help diagnose localized oedema in subcutaneous tissue in the inflammatory phase, prior to visible skin symptoms. It is a portable noninvasive unit with a display screen and an electrode designed to scan a patient’s unbroken skin whereby low frequency electrical current is applied and detected to measure degree of tissue electrical impedance as an indication of sub-epidermal moisture, a marker of pressure-induced tissue damage (e.g., pressure ulcer).