How to Assess Wounds for Tunneling and Undermining

by Laurie Swezey RN, BSN, CWOCN, CWS, FACCWS

As part of a thorough wound assessment, in addition to noting location and measuring size, the entire wound bed should be probed for the presence of tunneling and/or undermining. If you are unsure what tunneling and undermining are and how to recognize these phenomena, here’s an explanation of these terms and how to assess wounds for their presence.

Tunneling Wounds

Tunneling is caused by destruction of the fascial planes which results in a narrow passageway. Tunneling results in dead space that has the potential for abscess formation. To measure tunneling, a probe is gently inserted into the passageway until resistance is felt. The distance from the tip of the probe to the point at which the probe is level with the wound edge represents the depth of the tunnel. Clock terms are often used to describe the position of the tunnel within the wound bed. This is helpful in identifying and remeasuring tunnel depth at a later time in order to assess progress of wound healing. Tunneling can occur in any wound, but it occurs most commonly in surgical wounds and wounds occurring from a neuropathic cause … read more