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Suturing: From Basics to Advanced — Complete Reference Guide

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PART 1: FUNDAMENTALS - Anatomy of Wound Healing

• Epidermis (outermost, no tensile strength)
• Dermis (provides tensile strength; key layer for deep sutures)
• Subcutaneous (fat + loose connective tissue; prone to dead space)
• Deep fascia / muscle

1. Hemostasis (0-minutes): Platelet plug, vasoconstriction
2. Inflammation (0-72 hours): Tissue swells - relevant to suture tension
3. Proliferative (day 3 - week 3): Collagen synthesis; scar has only 5-10% of original strength at 2 weeks
4. Remodeling (weeks to months): Scar reaches ~80% original strength by ~6 weeks

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PART 2: INDICATIONS FOR SUTURING

When to Suture (Primary Closure)

Wounds That Can Heal Without Sutures

• Simple lacerations < 2 cm on the hand/finger with well-approximated edges
• Small superficial abrasions
• Puncture wounds (suturing may trap bacteria)

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PART 3: CONTRAINDICATIONS TO SUTURING (PRIMARY CLOSURE)

Absolute Contraindications

Relative Contraindications

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PART 4: INSTRUMENTS AND EQUIPMENT

The Suture Tray - What You Need and Why

• Holds the needle during passage through tissue
• Key principle: The needle holder should be placed on the proximal 1/3 of the needle body, NOT at the swage (weak point) and NOT at the tip
• The wrist pronation/supination motion follows the curve of the needle - this is critical (rotating the wrist to drive the needle in an arc rather than pushing it straight)

• Used to gently stabilize wound edges
• Never crush the dermis - use toothed forceps (Adson's) for skin; teeth allow grip without crushing
• Crushing the dermis with non-toothed forceps destroys capillaries and promotes necrosis

• Iris scissors: for cutting suture and fine dissection
• Suture scissors: blunt-ended for cutting near tissue

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PART 5: SUTURE MATERIALS - Selection and Reasoning

Absorbable vs. Non-absorbable

• Deep sutures must be absorbable: non-absorbable sutures buried in vascularized tissue cause chronic foreign body reaction, fibroblast proliferation, and sinus formation
• Scar has only 5-10% of original tensile strength at 2 weeks, so sutures must outlast this critical period
• Slowly absorbable monofilament (PDS, Maxon) retains >50% strength at 6 weeks - ideal for fascia closure
• Fast absorbable sutures (Vicryl Rapide) should NOT be used for fascial closure - risk of dehiscence before healing is adequate

Monofilament vs. Multifilament (Braided)

Suture Size (USP Scale)

• Inversely proportional to diameter: 2-0 is thicker than 4-0
• Tensile strength is directly related to diameter
• Face: 5-0 or 6-0 (minimal scar marks, precision)
• Scalp: 3-0 or 4-0 (high vascularity, under tension)
• Trunk: 3-0 or 4-0
• Extremities: 3-0 to 5-0
• Deep dermal: 3-0 or 4-0 Vicryl/Monocryl
• Fascia: 0 or 1-0 PDS or Maxon

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PART 6: NEEDLE SELECTION

Needle Anatomy

• Swage (where suture attaches): weakest point - never clamp here
• Body: held by needle holder
• Point: cutting or tapered

Needle Types

Needle Curvature

• 3/8 circle: most common; used for most skin sutures
• 1/2 circle: deeper wounds with limited access
• The curvature determines the arc of wrist movement needed - the needle holder wrist motion must follow the needle's curve exactly

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PART 7: PRE-SUTURING PREPARATION

Step 1 - Patient Positioning

• Place the patient and wound at elbow height
• Clinician should be seated or standing comfortably at one end of the long axis of the wound
• Adequate lighting is non-negotiable

Step 2 - Wound Assessment

• Depth (does it enter a body cavity?)
• Contamination (when? how? what?)
• Structures at risk (nerves, vessels, tendons, ducts)
• Tissue viability at edges
• Tension when edges are approximated

Step 3 - Anesthesia

• Local infiltration (1% or 2% lidocaine ± epinephrine)
• Epinephrine reduces bleeding and prolongs anesthesia; historically avoided in digits/nose/ear/penis but current evidence supports its cautious use in digits with normal vascular exam
• Allow at least 5-10 minutes for epinephrine effect
• Warning: Epinephrine provides temporary vasoconstriction - increased bleeding may occur once it is metabolized post-procedure

Step 4 - Irrigation and Debridement

• Copious irrigation with normal saline under pressure (minimum 200-500 mL for traumatic wounds)
• Remove all foreign material and devitalized tissue
• This is the most important infection-prevention step

Step 5 - Skin Preparation

• Povidone-iodine or chlorhexidine to surrounding skin
• Sterile draping
• For facial wounds: leave landmarks visible; use a clear drape or leave undroped with wide cleansing
• Hair management: tuck into draping or scrub hat

Step 6 - Assess Tension

• Approximate wound edges manually before suturing
• If wound edges don't come together easily: undermining is required
• Decide on layered vs. single-layer closure

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PART 8: FUNDAMENTAL TECHNIQUE - BEFORE ANY STITCH

Undermining

1. Use a #15 scalpel blade held parallel to the skin surface, OR spread scissors in the correct tissue plane
2. Undermine at a distance from each wound edge approximately equal to the width of the wound gap
3. The correct plane is at the junction of dermis and subcutaneous fat (for skin undermining), or in the subcutaneous fat layer
4. This creates a flap that can be lifted and advanced toward the wound

Wound Edge Eversion - The Golden Principle

• A slightly everted wound edge, when it contracts during remodeling, flattens to a level surface
• An inverted edge contracts to a depressed, pitted scar
• Eversion is achieved by angling the needle away from the wound edge on entry (so the bite is wider deep than at the surface - the "bottle-shaped" stitch)

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PART 9: STEP-BY-STEP SUTURING TECHNIQUES

TECHNIQUE 1: Simple Interrupted Suture

1. Load the needle: Clamp the needle holder at the proximal 1/3 of the needle body. Verify the needle is perpendicular to the needle holder jaws.
2. Enter the skin: Place the needle 2-3 mm from the wound edge, perpendicular to the skin surface. Reasoning: Entry at 90° combined with wrist rotation drives the needle in an arc, carrying more subcutaneous tissue than surface tissue - this creates eversion.
3. Drive through with wrist rotation: As the needle enters, pronate then supinate the wrist following the needle's own curve. Do NOT push the needle straight - let the curve do the work.
4. Cross the wound base: The needle tip exits in the wound base or on the contralateral wound edge. The stitch must be wider at the base than at the surface (bottle-shaped or flask-shaped).
5. Exit the contralateral side: Exit the skin the same 2-3 mm from the wound edge as entry. Exit at the same depth as entry to ensure level wound edges.
6. Pull suture through: Leave a 2-3 cm tail on the entry side.
7. Tie the knot (Instrument Tie - preferred):
   • Hold the long strand (needle end) 8 cm from exit point
   • Wrap the long strand clockwise once around the closed needle holder tip (single twist = square knot first throw)
   • Grasp the short tail with the needle holder tip
   • Pull short end toward you, long end away from you - this brings the first throw square to the skin
   • Tension: edges should just touch, not bunch
   • Reverse direction for the second throw (counterclockwise wrap) - locks the knot
   • Add 2-3 more square throws for security (total 4 for monofilament, 3 for braided)
8. Cut the tails: Leave 3-4 mm tails for knot security.
9. Spacing: Place subsequent sutures to close gaps without overcrowding. Too few sutures = gaping between stitches. Too many = increased foreign material, tissue ischemia between puncture sites, higher infection risk.

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TECHNIQUE 2: Buried Dermal Suture (Deep Interrupted)

1. Enter the needle at the base of the wound on one side, driving from deep to superficial
2. Exit at the dermal-epidermal junction on the same side
3. Re-enter the needle on the contralateral side at the dermal-epidermal junction, driving from superficial to deep
4. Exit at the base of the wound, level with the first entry point
5. Pull both ends upward - the suture forms a heart-shaped or "U" configuration in the dermis
6. Tie the knot at the base of the wound, so the knot is buried deep - this prevents knot protrusion through the healing epidermis and reduces reaction
7. The knot must be buried because if left superficial it will eventually extrude

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TECHNIQUE 3: Horizontal Mattress Suture

1. Enter the skin 4-6 mm from wound edge, cross the wound, exit the same 4-6 mm from the opposite edge (as in a simple interrupted stitch)
2. Do NOT tie yet
3. Move 4-6 mm along the wound edge (parallel), re-enter the skin on the same side you exited, cross back through the wound, and exit on the original side
4. You now have two parallel bites crossing the wound
5. Tie the knot on the original entry side

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TECHNIQUE 4: Vertical Mattress Suture

1. Place a wide (far-far) bite: enter 6-8 mm from wound edge, pass deeply through the wound base, exit 6-8 mm from the opposite edge
2. Reverse direction: re-enter the skin 1-2 mm from the wound edge on the same side you just exited, make a SHALLOW bite just under the dermis, exit 1-2 mm from the wound edge on the original side
3. Tie the knot on the original side
4. The resulting stitch has both a deep (far-far) component and a superficial (near-near) component

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TECHNIQUE 5: Simple Continuous Running Suture

1. Place and tie an anchoring simple interrupted suture at one end of the wound, but cut only the short tail - the long strand continues as the running suture
2. Advance along the wound at 45° to the wound edge with each pass, crossing the wound at equal intervals (typically every 3-5 mm)
3. Re-enter on the opposite side each time at the same distance from the wound edge
4. Maintain even tension throughout - pull consistently with each pass
5. At the far end, leave the last loop without tightening - this loop serves as the "free tail"
6. Tie the working end (with needle) to this loop using an instrument tie

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TECHNIQUE 6: Continuous Locked Running Suture

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TECHNIQUE 7: Subcuticular (Intradermal) Running Suture

1. Place a buried anchoring stitch at one apex of the wound
2. Enter the needle horizontally into the dermis just inside the wound edge, parallel to the skin surface - do NOT break through the epidermis
3. Exit the needle within the dermis, then re-enter on the opposite side at the same depth, taking a small horizontal dermal bite
4. Advance along the wound alternating sides, with each bite offset slightly so entry and exit points are not directly opposed
5. At the far end, exit the skin 1-2 cm from the wound end; secure by tying to itself or taping the tails to the skin with steri-strips
6. For long wounds, create "relief loops" every 4-5 cm by looping the suture out through the skin and back - these facilitate removal

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TECHNIQUE 8: Half-Buried (Corner) Suture

1. Enter the skin on the non-flap side of the wound, 2-3 mm from the edge
2. Pass into the dermis of the flap tip - do not puncture the epidermis of the flap tip
3. Pass through the base of the flap tip in the dermal plane
4. Exit back through the non-flap side of the wound, matching the entry level
5. Tie the knot on the non-flap side

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PART 10: KNOT TYING - THE INSTRUMENT TIE

Square Knot (Standard)

• First throw: Wrap the long strand (needle end) clockwise once around needle holder tip
• Grasp short tail with needle holder, pull short end toward you / long end away from you - lay the throw down to the tissue level, with just enough tension to approximate edges
• Second throw: Wrap the long strand counterclockwise once around needle holder tip - this reverses direction and locks the square
• Pull down, tighten without disturbing the first throw
• Additional throws: 2 more for monofilament (total 4), 1 more for braided (total 3)
• Leave 3-4 mm tails

Surgeon's Knot

• First throw: double wrap around needle holder (clockwise twice)
• Second throw: single wrap counterclockwise
• More secure initially because the double loop generates greater friction before the second throw locks it
• Useful when you need the first throw to hold while dealing with tissue tension

Common Knot Errors

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PART 11: LAYERED CLOSURE - The Logical Approach

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PART 12: SUTURE REMOVAL TIMING

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PART 13: POSTOPERATIVE CARE

1. Pressure dressing: Apply immediately; leave intact 24-48 hours to minimize hematoma formation
2. Wound care: Clean with mild soap and water once to twice daily; reapply petrolatum jelly (preferred over antibiotic ointments due to allergy risk) and a non-adherent dressing
3. Activity restriction: Verbal and written instructions for wound protection
4. Infection signs to watch for:

• Streptococcus: Expanding erythema within 24-48 hours
• Staphylococcus: Erythema + purulent drainage at 2-5 days

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PART 14: COMPLICATIONS AND PREVENTION

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PART 15: ADVANCED CONSIDERATIONS

The Small Bite Technique for Abdominal Fascia

Barbed Suture Technology

Delayed Primary Closure

Bridging Sutures

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Quick Reference: Suture Type by Clinical Scenario

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• Fitzpatrick's Dermatology, 9th Ed., Chapters on Cutaneous Surgery - suture materials, techniques, and complications
• Roberts & Hedges' Clinical Procedures in Emergency Medicine, 7th Ed. - Chapter 35: Wound Closure Techniques
• Tintinalli's Emergency Medicine, 9th Ed. - Chapter 41: Wound Management
• Pfenninger & Fowler's Procedures for Primary Care, 3rd Ed. - Chapter 25: Knot Tying and Suturing Techniques
• Fischer's Mastery of Surgery, 8th Ed. - Chapter on Abdominal Wall Closure
• Bailey & Love's Short Practice of Surgery, 28th Ed. - Wound Closure
• Pye's Surgical Handicraft, 22nd Ed. - Wound Closure

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