Scar tissue forms any time your body heals from an injury, surgery, infection, or inflammation. On the surface, you can usually see it. Internally, you often can’t, which is why internal scar tissue tends to go unnoticed until it starts causing symptoms like pain, stiffness, or digestive problems. Knowing what to look for depends on where the scar tissue is and what structures it affects.
What External Scar Tissue Looks and Feels Like
Surface scars are the easiest to identify. A scar can appear flat, lumpy, sunken, or discolored compared to surrounding skin. It often feels different to the touch: thicker, harder, or smoother than normal skin. The texture difference is one of the most reliable signs, even when the color has faded over time.
Two common types stand out. Hypertrophic scars are thick, raised, and often reddish, but they stay within the boundaries of the original wound. Keloid scars also appear raised and firm, but they grow beyond the edges of the original injury, sometimes significantly. Keloids tend to look red or darker than the surrounding skin and can keep growing months or years after the wound has closed.
A third type, called a contracture, pulls the surrounding skin inward as it heals. Contractures are common after burns and create a visibly tight, puckered area of skin. If a contracture forms over or near a joint, it can restrict movement noticeably.
Signs of Internal Scar Tissue
Internal scar tissue is trickier because you can’t see it. It develops inside the body after surgeries, infections, or chronic inflammation, and you typically become aware of it only when it interferes with something: organ function, digestion, breathing, or movement. The symptoms depend entirely on the location.
Abdominal and Pelvic Adhesions
After abdominal or pelvic surgery, bands of scar tissue called adhesions can form between organs and tissues that aren’t normally connected. Adhesions are remarkably common. In a large review of over 100,000 surgical patients, about 9% developed small bowel obstruction afterward, and adhesions were the single most common cause, responsible for 56% of cases with a known cause. Laparoscopic (minimally invasive) surgery cuts the risk roughly in half compared to open surgery, but it doesn’t eliminate it.
Many adhesions cause no symptoms at all. When they do, the signs include chronic abdominal or pelvic pain, bloating, cramping, and changes in bowel habits. In more serious cases, adhesions can partially or fully block the intestines, leading to severe abdominal pain, nausea, vomiting, visible abdominal swelling, and inability to pass gas or have a bowel movement. That combination of symptoms after a prior surgery is a strong signal that adhesions may be involved and warrants urgent medical attention.
Lung Scarring
Scar tissue in the lungs, known as pulmonary fibrosis, thickens the tissue around the air sacs, making it harder for oxygen to reach your bloodstream. Early signs include a persistent dry cough and shortness of breath that gradually worsens, especially during physical activity. As it progresses, you may notice extreme fatigue, unintended weight loss, aching muscles and joints, and a distinctive widening and rounding of the fingertips or toes called clubbing.
Joint and Muscle Scar Tissue
After an injury or surgery involving a joint, scar tissue can form in and around the surrounding soft tissues. The hallmark sign is a loss of range of motion. You may feel tightness or stiffness that doesn’t improve with normal stretching, or a sensation of resistance when trying to fully bend or extend the joint. If the scar tissue isn’t addressed, the muscles and tendons nearby can also shorten and tighten, eventually leading to a permanent restriction called a contracture.
This is especially common after knee surgery, shoulder surgery, and fractures that required immobilization. The joint may feel “stuck” at a certain point in its range, and pushing past that point produces pain or a pulling sensation rather than a smooth stretch.
When Scar Tissue Affects Nerves
Scar tissue that forms around or on top of a nerve can produce a distinct set of sensations. You may feel burning, tingling, shooting pain, or unusual sensitivity in the area. In some cases, the nerve becomes so compressed or encased that you lose sensation entirely, leaving a patch of numbness near the scar. Both outcomes, heightened pain and lost sensation, can occur simultaneously in nearby areas if different nerve fibers are affected.
This is particularly common around surgical incision sites and areas of traumatic injury. If you notice persistent burning pain, electric-shock sensations, or numbness that radiates outward from a scar, the scar tissue is likely involving a nerve.
How Scar Tissue Is Diagnosed
External scars are diagnosed visually. A doctor can usually identify the type of scar and whether it’s a keloid, hypertrophic scar, or contracture based on its appearance, texture, and whether it extends beyond the original wound.
Internal scar tissue is harder to confirm. Abdominal adhesions, frustratingly, don’t show up well on standard imaging. CT scans and ultrasounds can reveal indirect signs, like a bowel obstruction caused by adhesions, but the adhesions themselves are often invisible until surgery. In many cases, the diagnosis is made based on your symptoms and surgical history rather than a definitive image.
For organ scarring, imaging is more useful. MRI is considered the gold standard for detecting scar tissue in the heart, where a contrast agent highlights damaged areas. Lung fibrosis typically shows up on a high-resolution CT scan as a characteristic pattern of thickening. Liver scarring can be assessed with specialized ultrasound techniques that measure tissue stiffness.
How Long Scar Tissue Takes to Form
Scar tissue doesn’t appear overnight. After an injury or surgery, your body goes through several healing phases. The initial inflammatory phase lasts a few days, followed by a rebuilding phase where new collagen is laid down over roughly three to four weeks. Then comes the remodeling phase, during which the collagen reorganizes and the scar gains strength. This final stage begins around four weeks after injury and continues for nine to twelve months before the scar is considered fully mature.
This timeline matters because scar tissue is most responsive to treatment during that remodeling window. The earlier you address excessive scarring, whether through physical therapy, stretching, massage, or other interventions, the better the outcome tends to be. Once a scar has fully matured, it becomes significantly harder to change its structure.
What Scar Tissue Feels Like Under the Skin
Even when you can’t see internal scar tissue, you can sometimes feel it. Scar tissue near the surface (under a healed incision, for example) often feels like a firm lump, ridge, or band beneath the skin. It’s denser than the tissue around it. Pressing on it may produce tenderness, a pulling sensation, or referred pain in a nearby area.
Deeper scar tissue, like adhesions around organs, can’t be felt with your fingers. Instead, you notice it through functional symptoms: pain with certain movements, digestive problems that developed after surgery, breathing that’s become progressively harder, or a joint that won’t move through its full range despite consistent effort. The pattern that ties these together is a decline in function that starts after an injury, surgery, or illness and doesn’t resolve on its own with time.