What is the Difference Between Tunneling and Undermining?

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Tunneling and undermining are both terms used to describe wounds that are not healing properly, but they refer to different types of wound complications.

  • Tunneling: This occurs when a wound extends deeper into the tissue than its surface, creating a channel or tunnel. Tunneling is caused by the destruction of the fascial planes, which results in a narrow passageway. It generally occurs in one direction and is more readily apparent.
  • Undermining: This refers to a separation of the wound edges from the surrounding healthy tissue, often creating a “pocket” under the wound surface. Undermining is caused by erosion under the wound edges, resulting in a large wound with a small opening. It generally includes a wider area of tissue than tunneling and may occur in one or more directions.

Both tunneling and undermining can be caused by various factors, including pressure, shear, moisture, and infection. Patients with chronic medical conditions, slow-healing ulcers, wound site infection, and poor wound care practices are at a higher risk of developing these complications. To assess and manage these types of wounds, it is crucial to understand the differences between tunneling and undermining, as well as the best ways to treat them.

Comparative Table: Tunneling vs Undermining

Tunneling and undermining are two different phenomena in wound assessment. Here is a table comparing the differences between them:

Feature Tunneling Undermining
Definition Tunneling is a channel or tunnel that extends from the wound base in a unidirectional manner, resulting from the destruction of fascial planes. Undermining occurs when the tissue under the wound edges is eroded, resulting in a large wound with a small opening.
Direction Unidirectional. It may occur in one or more directions.
Extent Penetrates more deeply into the tissue. Less extensive than tunneling.
Assessment To measure tunneling, a probe is gently inserted into the passageway until resistance is felt, and the distance from the tip of the probe to the point at which the probe is level with the wound edge is measured. Undermining is measured directly under the wound edge with a probe held almost parallel to the wound, stopping when resistance is felt.

Both tunneling and undermining are serious conditions that may not be easily visualized. They appear small when observed from the skin's surface, but these wounds are much bigger than they appear from the outside.