Placing a suture means stitching the edges of a wound together so they can heal with minimal scarring. The most common technique, the simple interrupted suture, involves passing a curved needle through both sides of a wound, pulling thread across the gap, and tying a secure knot. While the basic mechanics are straightforward, doing it well requires proper wound preparation, correct instrument grip, and precise needle placement.
Preparing the Wound
A suture placed into a dirty wound traps bacteria inside, so thorough cleaning comes first. The standard method is high-pressure irrigation: pushing sterile saline or clean tap water through a large syringe directly into the wound. The goal is enough force to dislodge debris and bacteria without damaging the tissue. For a typical laceration, plan on using 50 to 100 milliliters of fluid per centimeter of wound length. A relatively clean cut needs less, around 30 to 50 milliliters per centimeter.
Not every wound should be sutured. Puncture wounds and animal bites to the hands or feet carry a high infection risk and are almost never closed with stitches. Heavily contaminated wounds or those showing signs of infection are also poor candidates for immediate closure. In those cases, the wound is cleaned, left open, and reassessed later.
Numbing the area before stitching makes the procedure tolerable. Lidocaine injected around the wound edges is the standard approach. Without epinephrine, the safe limit is 4.5 mg per kilogram of body weight, up to 300 mg total. When epinephrine is added (which also helps reduce bleeding), the limit rises to 7 mg per kilogram, up to 500 mg.
Choosing the Right Needle and Thread
Suture needles come in two main shapes. Cutting needles have a sharpened triangular edge that slices through tough tissue like skin. Reverse cutting needles are the most common choice for skin closure because the cutting edge faces away from the wound, reducing the chance of the thread tearing through. Tapered needles, which push tissue apart rather than cutting it, work better for softer internal tissues like muscle or bowel.
Thread falls into two broad categories: absorbable and non-absorbable. Absorbable sutures break down on their own over weeks to months. They’re used for deep layers beneath the skin surface, internal tissue, and situations where removing stitches later would be difficult (such as inside a child’s mouth). When used on the skin surface, absorbable sutures tend to cause more inflammation and scarring, so fast-absorbing versions are preferred if they must be used externally.
Non-absorbable sutures stay intact indefinitely and need to be removed manually. Nylon is the standard choice for interrupted skin stitches. For tissues that heal slowly and need prolonged support, like tendons, fascia, and ligaments, non-absorbable thread is the better option.
Holding the Instruments
You need two instruments: a needle driver (also called a needle holder) and tissue forceps. The needle driver clamps and drives the needle through tissue. Hold it with your thumb and ring finger through the finger loops. This grip keeps the tip stable while your forearm rotates. A common mistake is using the index finger instead of the ring finger, which causes the tip to drift sideways and makes needle placement less accurate.
The tissue forceps go in your non-dominant hand. Use them to gently lift and stabilize the wound edge as the needle passes through. Avoid crushing the tissue, since excessive force damages cells and slows healing.
Load the needle into the driver by clamping it roughly one-third to one-half of the way back from the tip. The needle should be perpendicular to the jaws of the driver, with the point curving away from you and toward the wound.
Placing a Simple Interrupted Suture
The simple interrupted suture is the most fundamental and widely taught technique. Each stitch is independent, meaning if one fails, the rest still hold.
Start by inserting the needle into the skin on one side of the wound, approximately 3 to 5 millimeters from the cut edge. The needle should enter perpendicular to the skin surface. Use a scooping motion that follows the natural curve of the needle, driving it down through the tissue, across the wound base, and up through the opposite side. The exit point should also be 3 to 5 millimeters from the wound edge, directly across from where you entered. The goal is to capture equal amounts of tissue on both sides so the wound edges come together evenly.
Once the needle tip emerges on the far side, release it from the driver, re-grasp it near the tip, and pull the thread through until a short tail (about 2 to 3 centimeters) remains on the entry side. You’re now ready to tie.
Tying the Knot
The instrument tie is the standard method for securing sutures. It uses the needle driver to form loops around the thread, which saves material and gives you precise control over tension.
Hold the long end of the thread (attached to the needle) in your non-dominant hand. Place the needle driver between the two thread ends. Wrap the long end once around the jaws of the driver, then open the driver and grasp the short tail. Pull the short end back through the loop while drawing both hands apart evenly. This creates your first throw.
For the second throw, place the driver between the thread ends again and wrap the long end around it once more, but this time in the opposite direction. Grasp the short tail and pull it through. Pulling in the opposite direction creates a square knot, which lies flat and holds securely. If both throws go in the same direction, you get a granny knot, which slips.
Pull evenly with both hands to keep the knot symmetric. You can gently lift both ends upward and lower them to snug the knot down, but do this smoothly. Jerking the thread converts a square knot into loose hitches that can unravel. Most skin closures need a minimum of three throws for security.
The final tension matters. The wound edges should come together without blanching (turning white from pressure). Sutures tied too tightly cut off blood flow to the skin edges, which leads to tissue death and worse scarring. A small gap between the knot and the skin is fine.
Spacing and Number of Stitches
Space each suture roughly 3 to 5 millimeters apart along the wound. The exact spacing depends on the location and tension. High-tension areas like joints or the trunk may need stitches closer together. Low-tension areas like the face can tolerate wider spacing. Each stitch should bring the wound edges into gentle contact without overlapping or inverting them. After placing all stitches, cut each thread tail to about 5 millimeters above the knot.
When Sutures Come Out
Removal timing depends on location. Skin on the face heals quickly and sutures come out in 3 to 5 days to minimize scarring. The scalp and arms take 7 to 10 days. The chest, trunk, legs, hands, and feet need 10 to 14 days. The palms and soles, which bear constant mechanical stress, require the longest time: 14 to 21 days.
Leaving sutures in too long creates “railroad track” marks where the thread crosses the skin. Removing them too early risks the wound reopening. Adhesive strips applied after suture removal can provide additional support during the final stages of healing.
Tetanus Considerations
Any break in the skin raises the question of tetanus protection. If you’ve completed your primary vaccine series and received a booster within the last five years, no additional vaccination is needed regardless of wound type. For clean, minor wounds, a booster is recommended if your last tetanus shot was 10 or more years ago. For dirty or major wounds, that threshold drops to 5 years. Anyone with an unknown or incomplete vaccination history should receive a tetanus vaccine with any wound.