Wounds and wound healing
How a wound heals
Nearly every operation ends with a wound, and how that wound behaves over the following weeks accounts for a large share of what patients experience afterward. It is worth understanding what is actually happening under the dressing.
Healing happens in overlapping phases, not discrete steps.
For the first minutes, the priority is stopping bleeding. Platelets plug the injury and release signals that recruit everything that follows.
For roughly the first four days, the wound is inflammatory. White blood cells arrive to clear bacteria and dead tissue. This is why a normal incision is somewhat red, warm, swollen and tender in the first several days. Patients frequently interpret this as infection. Early redness and tenderness that is stable or improving is expected. Redness that is spreading, particularly after day four or five when it should be settling, is not.
From roughly day four through three weeks, the wound is proliferating. New blood vessels grow in, fibroblasts lay down collagen, and skin cells migrate across from the edges. If the wound is open, this is when you see the beefy red granulation tissue filling it in.
Then for months to years, the wound is remodeling. The disorganized collagen laid down early is progressively replaced with stronger, better-oriented collagen. This phase is the reason for two things patients ask about constantly. First, why lifting restrictions last six weeks: a wound has only a fraction of its final strength at two weeks and roughly half by six. Second, why a scar keeps changing for a year or more. A scar at six weeks is not the scar you will have.
Worth knowing: a healed wound never regains full strength. The ceiling is around 80 percent of the original tissue. This is not a failure of surgery. It is the biology.
Why some wounds are left open
Wounds close in one of three ways.
Primary intention is the standard: the edges are brought together with sutures or staples and heal directly. This is what we do when the wound is clean.
Secondary intention means the wound is deliberately left open and allowed to fill in from the bottom with granulation tissue. This takes far longer and leaves a broader scar, but it is the right choice when a wound is contaminated, because closing bacteria inside a sealed space reliably produces an abscess. If you woke up with an open wound and packing, this is why, and it is a deliberate decision rather than a complication.
Tertiary, or delayed primary closure, splits the difference: leave it open for a few days, let the inflammatory phase clear the contamination, then close it.
What makes wounds heal badly
Some factors you cannot change: age, prior radiation to the area, some medications like steroids and certain chemotherapies, and connective tissue disorders.
Some you can, and the two that matter most in my practice are these.
Smoking is the largest modifiable risk factor in surgery, by a distance. Nicotine constricts the small vessels that feed a healing wound, and carbon monoxide displaces oxygen on hemoglobin. Wound healing is an oxygen-dependent process, and the effect is not subtle: substantially higher rates of infection, dehiscence, and hernia formation. Four weeks of abstinence before an elective operation measurably improves outcomes. If you take one thing from this section, take that one.
Blood sugar control. High glucose impairs white cell function and collagen synthesis. Perioperative glycemic control is one of the more reliable predictors of whether a wound behaves.
Nutrition also matters, and protein specifically. You cannot build collagen without amino acids, and patients who are protein depleted heal poorly no matter what else is done correctly.
Common wound problems
A seroma is a collection of clear or straw-colored fluid in a space under the incision. Common, usually harmless, usually resolves. We tend not to drain them unless they are large or symptomatic, because putting a needle into a sterile fluid collection is a good way to make it a non-sterile one.
A hematoma is the same idea with blood. Most are managed expectantly; large or expanding ones sometimes need to go back to the operating room.
A surgical site infection typically declares itself between days four and seven with increasing pain, spreading redness, drainage, and often fever. Treatment usually means opening a portion of the incision to let it drain, which sounds worse than it is and generally provides immediate relief, with antibiotics if there is surrounding cellulitis.
Dehiscence means the wound comes apart. Superficial dehiscence, where the skin separates but the deep layer is intact, is a nuisance managed with dressings. Fascial dehiscence, where the deep abdominal wall layer separates, is a surgical emergency. There is a classic warning sign here that I want patients to know: a sudden increase in thin, pink, salmon-colored drainage from an abdominal incision, often several days out, often with a feeling that something gave way. That fluid is peritoneal fluid, and it means the fascia has opened underneath. Call immediately.
Wound vacs
A negative pressure wound therapy device, commonly called a wound vac, is a sponge sealed under an airtight dressing connected to suction. It works by removing excess fluid, reducing swelling, drawing the wound edges gently together, and stimulating granulation tissue formation. For large open wounds it has substantially reduced both healing time and the number of dressing changes required, and it is one of the genuine advances in wound care of the last few decades.
Scars
A scar matures over twelve to eighteen months, generally starting red, raised and firm and gradually flattening and fading. Judging your result before a year is premature.
A hypertrophic scar is thick and raised but stays within the boundaries of the original incision. A keloid grows beyond the original wound edges and is far more common in patients with darker skin and in certain locations, particularly the chest, shoulders and earlobes. Keloids are frustrating to treat and prone to recurrence.
Two things reliably help scar appearance and are worth doing: keep the scar out of direct sun for the first year, because ultraviolet exposure on immature scar tissue causes permanent hyperpigmentation, and use silicone sheeting or gel, which has the best evidence of any over-the-counter intervention. Most of the expensive scar creams do not outperform it.
When to call
Call your surgeon for spreading redness, drainage that is thick or foul, fever above 101.5, pain that is increasing rather than decreasing after the third or fourth day, a wound that opens, or any sudden change in the character or volume of drainage.
Do not spend a weekend deciding whether it is worth bothering us. It nearly always is, and a wound problem addressed on day one is a dressing change, while the same problem addressed on day six is an operation.