Sternum Lump After Open-Heart Surgery: Normal Healing or a Problem?

By Your Health Magazine Health Information Team

A sternum lump after open-heart surgery is often caused by normal swelling, healing tissue, a raised scar, or a prominent wire or bone edge. It is more reassuring when the lump is stable or gradually shrinking, the incision is closed and dry, and there is no increasing pain, redness, warmth, drainage, fever, or movement of the breastbone. However, a new, enlarging, painful, warm, draining, or pulsating lump—or one accompanied by clicking in the sternum—needs prompt medical evaluation.

Why a Lump Can Appear During Normal Healing

During many open-heart operations, the surgeon divides the sternum to reach the heart and then secures the two halves with wires. This approach is called a sternotomy. The skin and deeper tissues are also closed in layers. According to an overview of sternotomy and recovery, the wires generally remain in place while the breastbone heals.

Several normal changes can make the area feel lumpy:

Healing tissue: New collagen can create a firm ridge under or along the incision. This usually softens as the scar matures.
Postoperative swelling: Mild swelling may remain around the incision during the early recovery period.
A raised scar: A hypertrophic scar stays within the original incision but may look thick, pink or red and feel firm or itchy. A keloid extends beyond the incision’s borders.
A prominent wire or bone edge: A small, hard, fixed spot may be more noticeable in someone with little tissue over the sternum or after postoperative weight loss.
The xiphoid process: The pointed lower end of the sternum can feel like a hard bump near the bottom of the incision.

Sternal bone healing commonly takes about six to eight weeks, although recovery varies and complete comfort may take longer. Scar remodeling continues for months. Follow the restrictions provided by your surgical team rather than assuming that the outside appearance means the deeper tissues are fully healed.

Normal-Looking Lump or Possible Complication?

Feature	More Consistent With Healing	Needs Medical Review
Size	Stable or gradually becoming smaller	Growing, appearing suddenly or returning after it had resolved
Skin	Closed, dry and becoming less red	Increasing redness, warmth, opening or drainage
Discomfort	Mild tenderness that improves	New, severe or steadily worsening pain
Sternum	Feels solid during movement and coughing	Clicking, popping, grinding or visible movement
General symptoms	No fever or worsening illness	Fever, chills, weakness or feeling increasingly unwell

This comparison cannot diagnose the cause. A lump that looks harmless may still require examination, particularly if it is new or changing.

Problems That Can Cause a Sternum Lump

Fluid or Blood Under the Skin

A seroma is a pocket of clear fluid, while a hematoma is a collection of blood. Either may produce swelling that feels soft, rubbery or fluid-filled. Small collections sometimes resolve, but an enlarging, tense or painful swelling should be assessed. Do not puncture or attempt to drain it at home.

Incision or Breastbone Infection

Infection can involve the skin, deeper tissue or sternum. Warning signs include increasing redness, warmth, tenderness, pus-like drainage, wound separation, fever or feeling sick. Review these heart-surgery incision-care warning signs, and follow the specific wound instructions given at discharge.

A deep sternal infection is uncommon but serious. Early contact with the surgical team is important because evaluation may involve an examination, blood tests, imaging or a sample of drainage.

Sternal Instability or Separation

The two halves of the sternum should remain stable while healing. Clicking, popping, shifting or movement during coughing, breathing or getting out of bed may indicate instability. MedlinePlus describes infection and separation of the sternum among the complications that may require sternal wound evaluation and treatment.

Raised Scar Tissue

A raised scar usually follows the incision line and may be firm, itchy or sensitive. It is less concerning when the skin is fully closed and there is no heat, drainage, spreading redness or increasing pain. Because scar treatments should not be applied to an incompletely healed incision, ask the surgeon before using silicone products, creams or massage. More information about expected scar changes is available in this guide to healing and caring for an open-heart surgery scar.

Bulge Near the Bottom of the Incision

A bulge below the breastbone that becomes more noticeable with coughing, standing or straining may represent an incisional hernia. This is different from a hard, fixed xiphoid process. A clinician may need to examine the area or order imaging to distinguish between them.

What to Do While Waiting for Medical Advice

Look at the incision daily. Note redness, drainage, opening or changes in the lump.
Track changes. A dated photograph or simple measurement can help the surgical team determine whether it is growing.
Do not squeeze, puncture or repeatedly press it. Manipulating the area may irritate healing tissue or introduce infection.
Do not begin scar massage unless cleared. The skin and deeper tissues must be sufficiently healed first.
Continue prescribed recovery precautions. Follow your surgeon’s directions about lifting, pushing, pulling, exercise and cardiac rehabilitation.
Contact the cardiac surgery team. The surgeon’s office is usually the best first call because it knows how the sternum was closed and what findings were present at discharge.

Open-heart surgery may be performed for several underlying conditions. The National Library of Medicine provides additional information about heart diseases and related care.

When to Seek Care

Contact the cardiac surgeon promptly or seek same-day medical care for a lump that is enlarging, increasingly painful, red, warm or draining. Also call for fever, chills, wound opening, a new clicking or shifting sensation, or any concern that the sternum is moving.

Call 911 for emergency symptoms such as severe or persistent chest pressure, major difficulty breathing, fainting, uncontrolled bleeding, or a rapidly expanding or pulsating chest lump. These symptoms should not be assumed to be part of normal recovery.

A stable lump without warning signs can usually be discussed at a postoperative visit, but contact the surgical team sooner if it worries you, persists without improvement, or appears months or years after surgery. An examination—and sometimes ultrasound, X-ray or CT imaging—is the only reliable way to determine what the lump represents.

This article provides general education and does not diagnose an individual condition or replace advice from your cardiac surgery team.