Suturing Techniques

Part of Surgery

Methods for closing wounds and surgical incisions using needle and thread to promote healing and reduce infection risk.

Why This Matters

A wound left open heals slowly, scars extensively, and remains vulnerable to contamination and mechanical disruption. A wound that is properly closed heals faster, stronger, and with less scarring. Suturing — stitching wound edges together — is the fundamental wound closure technique. It is also one of the most transferable medical skills: a person who can suture competently provides meaningful medical care with minimal equipment.

Suturing predates written history. Needles made from bone and sinew appear in archaeological records. Ancient Egyptian surgeons used metal staples. Indian surgeons in the Sushruta Samhita (600 BCE) described multiple suture types including deep absorbable sutures. The principles have not changed: approximate the wound edges without tension, without dead space, without compromising circulation.

This skill requires practice. Suturing on raw meat, a banana skin, or other materials before using on patients is strongly recommended. The goal is that the technique becomes automatic, so attention can focus on the wound itself.

Suture Materials

Absorbable Sutures (Break Down in the Body)

Used for internal layers — muscle, fascia, subcutaneous tissue. Do not need to be removed.

Catgut (historical): made from the submucosa of sheep intestine (not cat gut, despite the name). Natural absorbable suture used for centuries. Absorbed in 5-7 days (plain catgut) or 10-14 days (chromic catgut, treated with chromium salts to slow absorption). Can be made from the intestinal wall of any herbivore animal: clean the intestinal wall, strip into thin lengths, twist and dry.

Modern synthetic alternatives: polyglycolic acid (Vicryl) — if available from medical stocks, use until exhausted. Absorbed in 60-90 days.

Improvised absorbable suture: animal intestine preparation:

1. Clean fresh intestine, strip mucosa and outer layers to leave only the submucosal connective tissue
2. Cut into narrow strips (1-2 mm wide)
3. Twist or braid strips for strength
4. Dry under tension (prevents contraction)
5. Boil before use (20 minutes) to sterilize
6. These sutures absorb within 7-14 days — appropriate for internal use

Non-Absorbable Sutures (Must Be Removed)

Used for skin closure. Remain until removed at 5-14 days depending on location.

Silk: traditional non-absorbable suture. Silk thread, boiled to sterilize. Ties well, knots securely. Still appropriate for skin closure.

Linen thread: common cotton thread is too weak; linen thread (flax) is stronger and appropriate. Boil before use.

Fishing line (monofilament): if available, synthetic monofilament nylon (available from fishing supplies) makes excellent suture — strong, non-reactive, easy to sterilize. Use 2-0 or 3-0 equivalent gauge.

Plant fiber suture: twisted agave, hemp, or similar strong plant fiber. Not ideal but functional as an absolute last resort.

Selecting Suture Size

Suture is sized by gauge — larger number means thinner. Opposite of wire gauges.

Use	Appropriate gauge
Deep fascia	0 or 1
Muscle	2-0 or 0
Subcutaneous	3-0 or 2-0
Skin (trunk/extremity)	3-0 or 4-0
Skin (face)	5-0 or 6-0 (very fine)
Pediatric skin	4-0 or 5-0

Thinner suture leaves less scarring but has less strength. Use the thinnest suture that will reliably hold the wound closed.

Needles

Curved needle: most commonly used. The curve allows passage through tissue with a wrist rotation rather than a straight thrust — more control in confined spaces. Used for most suturing.

Straight needle: easier to use for skin in accessible areas; passes directly through.

Needle point types:

• Round (blunt-tipped): for muscle and visceral suturing — spreads fibers without cutting
• Cutting (triangular cross-section): for skin — cuts cleanly through tough dermis

Fabricating needles: Bone needles are effective for suturing — bone is hard enough to hold its point through multiple uses if properly finished. Smooth, curved bone needle with an eye drilled through the blunt end.

Steel needles can be made from wire: heat, bend to desired curve, hammer a flat end, drill or punch an eye. Sharpen the point on fine stone. Case-harden the tip for durability.

Knot Tying: The Foundation

A suture that does not stay tied is no suture at all. Knot tying is the most fundamental skill in suturing.

Square Knot

The standard surgical knot. Two throws in opposite directions that lock against each other.

1. Pass suture through the tissue
2. First throw: left over right, pull tight (not too tight)
3. Second throw: right over left, pull tight — this locks the first throw
4. Third throw: repeat direction of first throw for security
5. Three throws total for most sutures; five throws for slippery synthetic suture

Testing: after tying, the knot should not slip when the ends are pulled gently in opposite directions. If it slips, add another throw.

Common error: “granny knot” — both throws in the same direction. This slips under tension. Consciously alternate direction with each throw.

Instrument Tie

Tying with a needle holder when limited suture length is available:

1. Pass suture through tissue, leaving a 3 cm tail on one side
2. Wrap the long end twice around the needle holder
3. Grasp the short tail with the needle holder
4. Pull tight — the wrapping forms the first throw
5. Wrap once in the opposite direction around the needle holder
6. Grasp and pull — second throw locks the first

This allows tying with very short suture tails — useful in deep wounds.

Suture Placement Techniques

Simple Interrupted Suture

The most versatile and most commonly used technique. Each suture is a separate, independent stitch.

Technique:

1. Enter the skin 4-6 mm from the wound edge
2. Drive needle through skin, through the full thickness of the dermis, and out the opposite wound edge at the same depth
3. Ensure the needle exits symmetrically — same distance from edge, same depth as entry
4. Tie with a square knot
5. Cut, leaving 5 mm tails
6. Repeat every 5-10 mm along the wound

Advantages: if one suture fails, the others hold. Easy to adjust tension. Easy to remove selected sutures for drainage if needed.

Horizontal Mattress Suture

Provides excellent wound eversion (edge turning slightly outward — optimal for healing) and greater tensile strength.

1. Enter skin 8-10 mm from edge
2. Cross wound, exit same distance from opposite edge
3. Without cutting, advance along the wound 8-10 mm and re-enter the skin at same side as exit
4. Cross wound back, exit near starting point
5. Tie the two ends together

Each stitch is an H-shape and holds a segment of wound securely. Used for high-tension areas.

Continuous (Running) Suture

A single thread that runs along the entire wound without cutting between stitches.

Simple continuous: Place the first stitch and tie it. Do not cut. Continue placing stitches every 5 mm, drawing the thread snug with each. After the last stitch, tie off with a loop knot.

Advantages: fast, provides even tension distribution Disadvantages: if the thread breaks anywhere, the entire wound may open; cannot selectively remove a suture for drainage

Use for clean deep layers (fascial closure), not for skin in contaminated wounds.

Subcuticular Suture

Places suture just under the skin surface (in the dermis) without penetrating through. Results in minimal scarring — the knot is buried and there are no surface suture marks.

Technically more demanding. Useful for facial wounds or visible areas where cosmetic outcome matters.

Technique Principles

Eversion

Wound edges should be slightly everted (turned outward) rather than inverted (turned inward) or flat. Everted edges, when healed, produce a flat scar. Inverted edges heal with a depressed, grooved scar.

Achieve eversion by entering the needle slightly farther from the edge and including more dermis in the bite — the suture loop pulls the edges upward and outward.

Equal Bites

Each needle pass should take an equal amount of tissue from both sides of the wound. Unequal bites cause the wound to pucker or produce step-offs (one edge higher than the other).

Appropriate Tension

A suture should approximate edges, not strangulate them. Excessively tight sutures cut through tissue as post-operative swelling occurs. Check tension: the knot should hold the edges together with just enough contact — the skin under the suture should not be pale (which indicates excessive constriction).

When swelling is anticipated (freshly traumatic wound, facial wound): tie with minimal tension, or leave a small gap between the needle passes.

Dead Space

Any space inside a wound that is not filled by living tissue will fill with blood or serum — a perfect bacterial growth medium. Eliminate dead space with deep interrupted sutures that approximate the tissue before closing the surface.

When NOT to Close a Wound

Close primarily (immediately):

• Clean wounds sutured within 6 hours of injury
• Clean surgical incisions

Delay primary closure (leave open, close at 3-5 days if healthy):

• Wounds contaminated with soil, feces, or animal saliva
• Wounds older than 6-12 hours
• Wounds in which all dead tissue cannot be confirmed removed

Leave open entirely (heal by secondary intention):

• Infected wounds
• Abscess cavities
• Heavily contaminated wounds
• Wounds with extensive tissue loss

A closed infected wound is far worse than an open one. When in doubt about contamination: leave open.