How to Suture Skin: The Steps of Closing a Wound

Suturing skin follows a consistent sequence regardless of the wound: assess the injury, numb the area, clean the wound, choose appropriate materials, place stitches that bring the edges together with slight eversion, tie secure knots, and apply a dressing. Each step has nuances that affect whether the wound heals cleanly or develops complications, and skipping any one of them meaningfully raises the risk of infection or a poor scar. What looks like a simple needle-and-thread task is really a chain of decisions about tissue handling, tension, and timing.

Assessing the Wound

Before anything touches the wound, you need to evaluate what you’re dealing with. The factors that matter most are how the injury happened, how long ago it occurred, and how deep it goes through the skin and underlying tissue.¹ A clean, sharp cut from a kitchen knife is a very different animal than a jagged tear from a fall on gravel. Sharp-edged lacerations with minimal tissue damage tend to heal well with sutures. Crush injuries, bites, or wounds with ragged edges may need debridement (trimming away damaged tissue) before they can be closed, and some shouldn’t be sutured at all.

Timing matters too. Most uncomplicated wounds can be sutured within six to eight hours of injury, and the face often gets a longer window because of its rich blood supply. Wounds that present after this golden period carry a higher infection risk if closed primarily, and a clinician may choose to leave them open or use delayed closure instead. Depth determines whether you need a simple single-layer closure or a more involved layered approach, and it also determines whether deeper structures like tendons, nerves, or blood vessels need attention first. Tetanus risk should also be assessed at this point, because appropriate prophylaxis is an essential part of wound management.²

Numbing the Area

No one wants to feel a needle passing through their skin repeatedly, so local anesthesia is the standard first procedural step. Lidocaine is the most commonly used injectable anesthetic for laceration repair, and it often comes mixed with epinephrine. A trial comparing four injectable anesthetics for laceration repair found that lidocaine with epinephrine and buffered lidocaine with epinephrine provided significantly better pain control than buffered lidocaine alone or diphenhydramine with epinephrine.³ The epinephrine also constricts local blood vessels, which reduces bleeding and gives you a clearer field to work in.

The injection itself stings, which is one of the more dreaded parts of the whole process for patients. Injecting slowly, using a small-gauge needle, and buffering the lidocaine with sodium bicarbonate all reduce that initial burn. You inject into the wound edges rather than through intact skin when possible, and wait a couple of minutes for full effect before starting.

Cleaning and Preparing the Wound

Irrigation is the single most important step for preventing wound infection. The idea is simple: you flush the wound with fluid under pressure to physically remove bacteria, dirt, and debris. A syringe attached to a catheter tip generates enough pressure to dislodge contaminants without damaging the tissue itself. As for what fluid to use, the choice matters less than you might think. A study of over 500 patients compared normal saline, povidone-iodine solution, and a nonionic surfactant for wound irrigation before suturing, and found no significant difference in infection rates among the three.⁴

Even plain tap water holds up well. A randomized controlled trial directly comparing sterile saline with tap water for wound irrigation before suturing found no difference in infection rates, with a trend that actually favored the tap water group.⁵ This is reassuring for settings where sterile saline isn’t available, though most clinical environments use saline by convention. The volume of irrigation matters more than the specific solution. A general rule is at least 50 to 100 milliliters per centimeter of wound length.

After irrigating, any visibly dead tissue or foreign material that remains needs to be removed. Ragged wound edges can be trimmed to create clean, well-defined borders that will come together neatly. If the wound is contaminated enough that you suspect infection is already taking hold, suturing may be delayed or avoided entirely.

Choosing Suture Materials

Suture materials fall into two broad categories: absorbable and nonabsorbable. Absorbable sutures break down in the body over weeks to months and don’t need to be removed. Nonabsorbable sutures stay put indefinitely and must be taken out at a scheduled follow-up visit. For skin closure, both types have roles. Absorbable sutures are typically placed in the deeper tissue layers, while nonabsorbable sutures (usually nylon or polypropylene) close the skin surface.

A study comparing these materials in microsurgical settings found that nonabsorbable sutures were still fully recognizable at 150 days and showed clear signs of granuloma formation, while absorbable sutures were barely visible after 50 days and produced almost no lasting foreign body reaction.⁶ That ongoing foreign body response is part of why surface sutures are removed relatively early and why buried sutures are almost always absorbable.

Suture thickness is measured by gauge, with higher numbers indicating thinner thread. On the face, where cosmesis matters most and skin is thin, you might use 5-0 or 6-0 suture. On the trunk or extremities, 3-0 or 4-0 is more common. The thinner the suture, the less tissue reaction it produces, but it also has less tensile strength.

Picking the Right Needle

The needle attached to the suture determines how easily it passes through tissue and how much damage it causes along the way. For skin, most practitioners use a curved needle with a cutting edge. The two main designs are conventional cutting and reverse cutting. A conventional cutting needle has its sharp edge on the inside of the curve, which can create a tendency for suture to pull through the tissue toward the wound edge. A reverse cutting needle has the sharp edge on the outside, directing the cutting force away from the wound, which is generally preferred for skin.

Research comparing these needle geometries found that needle design significantly affects how easily tissue tears. Reverse cutting needles required more force to tear through tissue than conventional cutting needles, and taper point needles required the most force of all.⁷ However, when researchers measured the actual force needed to puncture skin, the difference between taper point and reverse cutting needles was not clinically significant.⁸ In practical terms, reverse cutting needles remain the standard for skin suturing because they combine easy penetration with good resistance to tearing.

Placing the Simple Interrupted Suture

The simple interrupted suture is the workhorse technique for skin closure and the first pattern any student learns. The goal with every stitch is to bring the wound edges together so they sit slightly raised, or everted. Skin has a natural tendency to flatten and contract as it heals, so edges that are initially everted will settle into a flush, flat scar. Edges that are placed flat will eventually invert and form a depressed, more visible scar. Controlling this eversion through proper needle path is a core skill.⁹

Here is the basic sequence for each stitch:

• Enter the skin: Insert the needle perpendicular to the skin surface, about 3 to 5 millimeters from the wound edge, depending on the tissue and location.
• Follow the curve: Rotate the needle holder to drive the needle along its natural arc through the dermis. The needle should pass deep to the wound floor, capturing more tissue at the base than at the surface to create that flask-shaped bite that promotes eversion.
• Exit the opposite side: Bring the needle out through the opposite wound edge at the same depth and distance from the edge, so the bite is symmetric.
• Tie the knot: Pull the suture through, leaving a short tail, and tie it with enough tension to approximate the edges without blanching the skin.

Good approximation, consistent tension, and precise edge alignment along the wound are what separate a clean closure from a lumpy one.¹⁰ Each stitch should be placed at equal intervals, and the wound edges should meet without overlapping or gapping. Pulling too tight strangles the tissue and increases scarring. Leaving it too loose allows the edges to separate.

Layered Closure and Buried Sutures

For any wound deeper than the superficial dermis, a single layer of skin sutures usually isn’t enough. Deeper wounds benefit enormously from layered closure, where absorbable sutures are placed in the subcutaneous tissue and deep dermis before the skin surface is closed. These buried sutures take tension off the surface stitches, hold the wound together during the early healing period, and dramatically reduce the final scar width.

The buried vertical mattress suture, introduced in 1989, was a landmark development. Its key feature is that the suture is placed snugly against the undersurface of the epidermis, about 3 to 4 millimeters from the wound edge, and exits in the deeper dermis. This was the first buried suture technique to produce wound eversion rather than simply flat apposition, and it remains the most widely used subcuticular suture among dermatologists and plastic surgeons.¹¹ For narrow wounds or tight spaces where a vertical approach is awkward, the buried horizontal mattress suture changes the needle direction from vertical to horizontal while achieving a similar result.¹¹

Layered closure is one of the most effective intraoperative measures for reducing scarring. By relieving tension across the healing wound through techniques like layered closure, undermining, and appropriate suture selection, surgeons support the healing process and minimize scar formation.¹²

Tying Secure Knots

A perfectly placed suture is useless if the knot slips or unravels. Knot security depends on the suture material, the number of throws (loops), and the configuration of the knot. A comprehensive review found that the optimal number of throws varies by knot type: surgeon’s and square knots generally need three to five throws to be secure, while the Aberdeen knot reaches peak security with just three throws and one to two turns. Across all configurations, a tail length of about 3 millimeters is optimal.¹³

Monofilament sutures like nylon and polypropylene are inherently slipperier than braided sutures, so they typically require more throws to hold. Braided sutures grip themselves better but also harbor bacteria more easily due to their woven structure. Surgeon experience also plays a role. Testing of knot security and tensile strength across different suture types showed significant differences in how likely knots were to fail, and the experience of the person tying had a measurable effect on both failure mode and the load the knot could withstand.¹⁴ The basic principle is to alternate the direction of each throw so the knot lies flat (a square knot) rather than stacking throws in the same direction, which creates a less secure granny knot.

Reducing Tension and Minimizing Scars

Tension across the wound is the single biggest modifiable factor in scar quality. Skin under tension heals with wider, thicker, more prominent scars, and in susceptible individuals, excessive tension contributes to keloid and hypertrophic scar formation. Research has shown that subcutaneous and fascial tensile reduction sutures, which shift mechanical load away from the dermis, are more effective at preventing abnormal scarring than traditional multilayer closure techniques.¹⁵

A novel step-type tension-relieving suture technique was evaluated against conventional suturing in a clinical trial, and at 12 months the tension-relieving group had significantly better scar scores on validated assessment scales and narrower average scar width.¹⁶ Other strategies for reducing tension include undermining (freeing the tissue beneath the skin edges so they come together more easily), orienting incisions along natural skin tension lines when possible, and using skin flaps in cases where direct closure would put excessive strain on the wound.

Timing of suture removal also affects scarring. The longer skin sutures stay in, the more likely they are to leave permanent crosshatch marks from the entry and exit points. On the face, sutures are typically removed at five days. On the trunk and extremities, seven to fourteen days is more common. The buried dermal sutures underneath continue to hold the wound together long after the surface stitches come out.

Post-Operative Wound Care

After suturing, the wound is typically dressed with a simple bandage. There is a common assumption that applying antibiotic ointment to the closure helps prevent infection, but a systematic review and meta-analysis found that in the setting of moist occlusive dressings, there is no significant difference in prophylactic benefit between applying and not applying ointment to surgical wounds.¹⁷ Keeping the wound moist and covered is what matters; adding antibiotic ointment on top of that does not meaningfully change infection rates, and it can cause contact dermatitis in some people.

Patients are generally instructed to keep the wound dry for the first 24 to 48 hours, after which gentle washing is acceptable. Avoid submerging the wound in standing water (baths, pools, hot tubs) until the sutures are out and the wound has sealed. Signs that warrant a return visit include increasing redness that spreads beyond the wound margins, warmth, swelling, purulent discharge, fever, or red streaking along the skin away from the wound.

Complications Worth Knowing About

Even with proper technique, complications occur. A prospective study of sutured wounds found a total wound-related complication rate of about 16%, with infection being the most common at 10%. Wound dehiscence (the wound edges pulling apart) occurred in about 4% of patients and was often associated with poorly controlled diabetes or technical problems like excessive tension.¹⁸ The same study found that the vertical mattress technique was associated with the highest infection and dehiscence rates, likely because its deeper dermal penetration and greater suture tension create more tissue trauma.¹⁸

Other potential problems include suture granulomas (small inflammatory nodules that form around retained suture material), allergic reactions to suture materials, and hematoma or seroma formation beneath the closure. Most of these are manageable with simple interventions, but they underscore why follow-up after wound closure is not optional.

When Sutures Are Not the Best Option

Sutures are the gold standard for most wound closures, but they are not the only tool available. Tissue adhesives (skin glue), adhesive strips, and surgical staples all have roles depending on the wound’s location, depth, and tension.

A multicenter randomized trial comparing absorbable sutures, staples, and tissue glue for closing small surgical port sites found that sutures produced the best cosmetic results, with the lowest scar scores on both observer and patient assessment scales across multiple dimensions including vascularity, pigmentation, thickness, and pliability. Staples were the fastest to place. Tissue glue had a trend toward higher wound complication rates, though the overall difference was not statistically significant.¹⁹ Sutures were also the most cost-effective and produced the least non-recyclable waste.

Tissue adhesives work well for superficial, low-tension wounds where the edges come together easily on their own, particularly on the face in children where avoiding needles is a real practical advantage. Adhesive strips can reinforce a closure or serve as the primary method for very superficial cuts. Staples excel on the scalp, where cosmesis is less critical and speed matters, such as in trauma settings.

How Instrument Handling Affects Quality

Suturing is a manual skill, and the instruments you use influence fatigue and precision. Research on endoscopic needle drivers found that handle design significantly affected the surgeon’s muscle work and joint movement during suturing. Ball-shaped and rocker-style handles produced better task quality and efficiency than traditional finger-loop instruments, with lower muscle fatigue in the arm flexors and shoulder muscles.²⁰ While this study focused on endoscopic work, the principle applies to open suturing as well: ergonomic instrument handling reduces fatigue and improves consistency, especially during longer closures.

For open skin suturing, a standard needle driver is held in the palm of the dominant hand with the thumb and ring finger in the rings, and the index finger extended along the shaft for stability. The tissue forceps in the nondominant hand gently evert the skin edge as the needle passes through. Gripping too hard with the forceps crushes the tissue at the wound edge, which impairs healing and worsens scarring. Gentle handling with toothed forceps, which grip without requiring much squeeze force, is preferred over smooth forceps that demand a tighter grip to hold tissue.

A Very Old Skill That Keeps Evolving

Wound closure with thread is one of the oldest surgical techniques in existence. Ancient civilizations in India and Africa used plant fibers, hair, and animal tendons to close wounds. The Edwin Smith papyrus, dating to about 1600 BCE, described wound closure with linen threads, and Sushruta, around 500 BCE, introduced catgut sutures and even used the jaws of black ants as natural staples.²¹ The core principle has not changed in thousands of years: bring wound edges together and hold them there while the body heals. What has changed is the sophistication of the materials and the understanding of how technique choices affect outcomes. Modern synthetic absorbable sutures provoke far less tissue reaction than catgut ever did, and techniques like the buried vertical mattress suture have transformed scar quality in ways that would have seemed remarkable even a few decades ago. The next frontier involves tension-offloading devices and bioactive wound-closure materials, but the fundamental steps of assessing, cleaning, approximating, and protecting remain exactly what Sushruta would recognize.