All About Tunneling Wounds and Their Treatment

Tunnels beneath the skin’s surface indicate a wound that isn’t healing properly. Tissue is being lost, and without appropriate care, more severe complications can develop.

An open sore is distressing to see. But what lies hidden beneath the visible wound can be even more troubling.

Read on to learn why tunneling wounds develop, how they’re managed, and whether you can reduce your risk of getting them.

What is a tunneling wound?

A tunneling wound is one that has progressed to create channels underneath the skin’s surface. These tunnels may be short or extensive, shallow or deep, and can twist or branch.

Tunneling is commonly seen in stage 3 and stage 4 pressure injuries.

How is a tunneling wound diagnosed?

A wound may look superficial but, if not treated appropriately, can evolve into a tunneling wound. Because tunnels aren’t always obvious, it’s important to have any wound assessed by a clinician.

A healthcare provider will probe the wound to determine whether tunnels exist, how long and deep they are, and in which directions they extend.

Tunneling wounds demand careful care to prevent deeper extension and to stop new channels from forming. Without proper treatment, additional tissue can be destroyed and infection may spread, potentially causing serious complications, even life-threatening ones.

These wounds must be followed closely until complete healing occurs.

What can cause a tunneling wound?

Multiple factors may lead to tunneling wounds, and certain health conditions increase vulnerability.

Delayed healing

Tunneling can develop when inflammation persists and the wound fails to progress. Other elements that impede healing include:

• a sedentary lifestyle
• tobacco use
• placing excessive weight or pressure on the wound
• corticosteroid medications, which may reduce collagen production
• nonsteroidal anti-inflammatory drugs (NSAIDs), which can hinder protein synthesis and wound contraction
• chemotherapy or drugs that suppress the immune system

Medical conditions that can slow recovery include:

• diabetes
• rheumatoid arthritis
• venous insufficiency
• malnutrition
• obesity
• alcohol use disorder
• a weakened immune system
• zinc deficiency
• advanced age

Infection

An infected wound can destroy surrounding tissues. Things that raise infection risk include:

• long-term antibiotic use, which can promote resistant infections
• inadequate wound care
• diabetes, which may cause nerve damage and reduce blood flow

Pressure

When opposing forces concentrate at tissue junctions, pressure can cause separation of layers and create tunnels beneath the skin.

Wound packing and dressings

Packing a wound correctly requires careful assessment. Overpacking can dehydrate the wound and harm tissue; underpacking may fail to absorb drainage. Regular monitoring and adjustment of packing are important.

Hidradenitis suppurativa

Hidradenitis suppurativa is a chronic skin condition where small, painful nodules form beneath the skin, especially where skin rubs together — such as the armpits and groin. These areas can develop interconnected tunnels.

The exact cause is unclear but may involve hormonal, genetic, and immune system factors. It’s more common in women than men and typically appears between ages 18 and 29. For more information on related complications, see hidradenitis suppurativa tunnels.

Pilonidal cyst

Pilonidal cysts form in the cleft between the buttocks. They are relatively common and may occur once or repeatedly. If left untreated, pilonidal cysts can progress to tunneling.

They affect men more frequently than women and often arise between puberty and about age 40. Risk factors include prolonged sitting, excess body weight, and dense body hair.

How are tunneling wounds usually treated?

Identifying the cause of a tunneling wound guides the treatment approach. Because tunnels may curve and traverse multiple tissue layers, a thorough examination is necessary. Imaging tests are sometimes used to reveal the full extent of the tunneling.

In all cases, the area must be cleansed and devitalized tissue removed. Ongoing monitoring is essential during the healing process.

Packing and dressings

Packing assists healing and reduces the chance of abscess formation. It should be snug enough to prevent collapse of the wound but not so tight that it causes further damage. Your clinician may change packing as the wound improves.

Avoiding pressure on the wound is important.

Medications

Medications for tunneling wounds can include:

• antibiotics to treat or prevent infection
• analgesics for pain relief
• systemic therapies and topical antibiotics (used for hidradenitis suppurativa)
• phenol injections (sometimes used for pilonidal cysts)

Drainage

Draining the wound encourages the formation of granulation tissue — the connective tissue that helps close the wound.

Negative pressure wound therapy

Negative pressure wound therapy reduces local air pressure to decrease swelling, remove bacteria, and speed healing. It’s also called vacuum-assisted closure.

The clinician will apply a dressing sealed with adhesive film and attach a drainage tube to a portable suction pump that removes air pressure.

While undergoing treatment, you’ll need to carry the pump and have dressings changed periodically, sometimes for several weeks.

Surgery

A variety of surgical procedures may be necessary to excise damaged tissue, remove cysts, or expose and clean out tunnels.

Managing underlying conditions

You and your care team should address and control any underlying health issues. For example, if you have diabetes, closely monitoring blood glucose is crucial.

Can tunneling wounds be prevented?

They can’t be completely avoided, but you can reduce your risk. Prompt evaluation and treatment of any open wound are important.

• Manage and monitor chronic conditions such as diabetes.
• Keep even minor wounds clean and dry.
• Stay mobile, but avoid putting pressure on the wound.
• Follow your clinician’s guidance for wound care and surveillance.
• Take antibiotics exactly as prescribed.

Contact your provider if you notice:

• sudden or severe pain
• increased redness or swelling
• discharge or a bad smell from the wound
• fever, chills, or drenching sweats

What is the outlook and healing time?

Tunneling wounds and their treatment can be uncomfortable. They are often difficult to manage and may require weeks or months to fully heal. Pilonidal cysts in particular can recur after apparent healing.

If healing stalls, tunneling wounds can become life-threatening. With timely, appropriate care, however, they tend to heal more quickly and with less pain.

Any wound that breaks the skin can leave a scar; the size and appearance depend on the injury and healing process.

Key takeaways

A tunneling wound develops when channels form beneath the skin’s surface. Multiple factors — including infection and impaired healing — can contribute to their formation.

These tunnels aren’t always visible, yet they represent a serious problem. Accurately assessing the extent of tunneling and initiating correct treatment promptly are critical. Improper care may lead to severe, even life-threatening, complications.

Tunneling wounds may take from several weeks to several months to resolve.