Needles, Knots, and Sutures


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By the end of this unit, the learner should be able to do the following:

  • Identify the types of needles available and common indications for their use
  • Identify the types of available sutures and appropriate indications for their use
  • Describe the difference between absorbable versus nonabsorbable, monofilament versus multifilament, and natural versus synthetic suture
  • Demonstrate capacity for two-handed knot tying, one-handed knot tying, surgeon’s knots, deep tying, and instrument tying
  • Demonstrate capacity for appropriate needle handling and knowledge of running sutures, running-locked sutures, and interrupted sutures

The Basics: Suture Needles

Types of surgical needles.
Reproduced with permission from: Mizell JS. Principles of abdominal wall closure. In: UpToDate, Post TW (Ed), UpToDate, Waltham, MA. (Accessed on April 12, 2017.) Copyright © 2017 UpToDate, Inc. For more information visit

Anatomy of Surgical Needles

Needle Material

  • Stainless steel alloy
  • Some coated with silicone to assist with passage through tissue

Needle Anatomy

  • Point: section going from tip to maximum cross section
  • Body: most of needle length (strongest area, so this is the part you will grasp with the needle driver)
  • Swage: place where suture is attached to needle

Parts of a surgical needle.


  • Two opposed cutting edges to penetrate through difficult tissue
  • Can be straight or curved


  • Pierces and spreads tissue without cutting it
  • Use in easily penetrated tissue


  • May be used in tissues that are less dense
  • May cause less glove penetration in the event of needle stick injury
  • May take more effort to push through certain tissues and are more user-dependent

Body Types

  • Straight: Good for suturing tissue that is manipulated directly by hand, rarely used in gynecologic surgery
  • Curved
    • Predictable path through tissue
    • Requires less space
    • Provides an even distribution of tension
    • Size should match tissue thickness & desired stitch depth
Curved and straight needles.
Image courtesy of Angela Chaudhari, MD

Selecting the Needle Type

Needle point

  • Tapered: usually used on tissues inside the body
  • Cutting: usually used for skin and tough tissue like tendon and bone
  • Blunt: usually used in less dense tissues and may be used for uterine and fascial closure during Cesarean delivery to decrease needle sticks. They should be avoided in skin and bowel.

Size of needle

  • The size should match the depth of the tissue you are re-approximating
  • The size should match the intended stitch depth and length

Proper Needle Handling Tips

  • Avoid placing your fingers in the finger holes of the needle driver–this will limit your mobility
  • Position the tip of the needle driver one third to one half of the way from the swaged end of the needle
  • Place the needle at right angles to the tissue
  • Use your wrist to turn the needle through tissue, not your fingers or your elbow or body. Position your body so that your wrist is in the optimal position to maneuver the needle.
  • After driving the needle through tissues, stabilize it with tissue forceps at the level of tissue and feed the needle through the tissue until you can re-grasp the body of the needle with needle driver one third of the way from the swaged end.
  • Be aware of the needle location at all times and keep within the sterile field
  • ‘Protect’ the needle tip within the jaws of the needle driver when you give it back to the scrub tech/nurse

Suture Properties

Suture properties influence how you decide which one to choose. Suture properties are determined by a combination of suture material (absorbable vs. non-absorbable, natural vs. synthetic, monofilament vs. braided):

  • Tensile strength: based on thickness and suture material
  • Absorbable versus non-absorbable
  • Reactivity: this means the degree of tissue inflammation that happens around the suture, it is determined by suture material
  • Handling characteristics:  this means the amount of friction as suture slides through tissues, it is affected by a combination of suture material, and whether the suture is monofilament or braided
  • Knot security: this is affected by the same suture properties that affect handling characteristics
  • Smooth versus barbed

Suture Strength: Material and Size

  • Below are materials listed from weakest to strongest:
    • Plain gut
    • Chromic gut
    • DexonTM / vicryl® / polysorbTM
    • MaxonTM / PDS
    • Silk
    • Nylon
    • Polypropylene (strongest)
  • Size
    • Size is described using numbers: 5-0, 4-0, 3-0, 2-0, 0
    • The higher the first digit, the thinner and weaker the suture

*Note: Any and all references to trademarks or registered companies are for educational purposes only. ACOG is in no way endorsing or promoting any product in these educational materials.

Absorbable or Nonabsorbable Sutures

A goal of suture selection is to find a suture that provides the necessary strength during tissue healing that disappears soon after healing is done.

  • Absorbable sutures
    • Natural sutures are digested by body enzymes and have more tissue reactivity than synthetic sutures
    • Synthetic sutures are hydrolyzed, water penetrates suture filaments leading to breakdown
    • May retain strength for up to two months
  • Nonabsorbable sutures
    • Not digested by body enzymes
    • Use in exterior skin closures, patients with prior tissue reaction to absorbable sutures, or as permanent sutures within tissue
    • May retain strength for longer than two months

Monofilament or Multifilament Sutures

  • Monofilament
    • Made of a single strand
    • Less resistance as they pass through tissue and tie down easily but hold knots less well
    • Decreased infection rates at suture line
  • Multifilament
    • Several filaments braided together
    • May be coated to pass smoothly
    • Greater flexibility and handling
    • Better knot security
    • Can serve as a nidus for bacteria

Synthetic or Natural Sutures

Synthetic Sutures

  • Absorbable
    • Polyglycolic acid (DexonTM)*
    • Polyglactin 910 (Vicryl®)
  • Delayed absorbable
    • Polydioxanone (also PDO, PDS)
    • Polyglyconate (MaxonTM)
  • Nonabsorbable
    • Polyamide (nylon)
    • Polyester (Dacron®)
    • Polypropylene (Prolene®)
    • Polytetrafluoroethylene (PTFE, GORE-TEX®)

Natural Sutures

  • Absorbable (cat gut) Multifilament
    • Plain
    • Chromic
  • Nonabsorbable
    • Silk (multi-filament)
    • Linen
    • Stainless steel wire (mono-filament)

*Note: Any and all references to trademarks or registered companies are for educational purposes only. ACOG is in no way endorsing or promoting any product in these educational materials.

Knot Security

  • Depends on the force the suture can stand before it breaks when it’s knotted
  • Strength should be similar to the tissue that it is used in
  • Depends upon suture memory, elasticity and type of filament
    • Memory: the ability of suture to return to its original shape, ‘stiffness’ of the suture
    • Elasticity: the ability to stretch and return to original length
    • Monofilament sutures are more slippery and have more memory, so they hold knots less well

Barbed Sutures

  • Barbs along the length of the suture anchor the suture in the tissue
  • Decreases reliance on knots
  • Distributes tension across the entire length of the suture
  • Can decrease suturing time in some gynecologic surgeries and cesarean delivery
  • No clear reduction in blood loss
  • Description of the se of these sutures is beyond the scope of this module

A barbed suture.

A section of barbed suture showing the needle, barb, arm, and transition point.

Images courtesy of Angela Chaudhari, MD

Types of Knots

Square Knot (two-handed technique)*

A square knot is the fundamental knot used in surgery. When appropriately performed, it provides optimal strength and minimal slippage.

Square Knot (one-handed technique)*

This square knot is an alternative to the two-handed technique for more advanced surgeons. 

Surgeon’s Knot

The surgeon’s knot is a “friction knot,” used with some sutures, eg, coated vicryl, to prevent knot slippage after the first throw.

Videos in simulation, courtesy of Angela Chaudhari, MD.* Access videos for these types of knots in the Simulation tab.

Knot-Tying Principles

  1. The completed knot must be firm to eliminate slippage. The simplest knot for the material used is the most desirable, which is why most surgeons prefer a two-handed tie
  2. Tie the knot as small as possible and cut the ends as short as appropriate for the suture material. This helps prevent excessive tissue reaction to absorbable sutures and helps minimize foreign body reaction to nonabsorbable sutures
  3. "Sawing" between the strands creates friction, and may weaken suture integrity so put down knots smoothly
  4. When securing your knot, push the knot down toward the tissue you are securing (see image of deep tie technique). Resist the urge to pull up on the suture. Too much upward tension on the suture strands will pull on the tissue and your suture may cut or pull through tissue
  5. Grasping suture with surgical instruments damages and weakens the suture material. Grasp the suture as much as in necessary to manipulate it, but avoid grasping and re-grasping, especially with instrument ties
  6. Tying sutures too tightly will contribute to tissue strangulation and weaken the knot. This is particularly important on fascia
  7. Maintain traction at one end of the strand after the first loop is tied to avoid loosening of the throw
  8. Change the position of your hands, arms or body relative to the patient, in order to place a knot securely and flat
  9. Extra throws will not strengthen a properly tied knot

Deep Tie

The deep tie technique avoids upward tension on tissue.

Deep tie.
Image courtesy of Angela Chaudhari, MD

Instrument Tie

This technique is used when one or both ends of the suture are short.

Instrument tie.
Image courtesy of Angela Chaudhari, MD

Suture Techniques

The next several slides have images of each of these suture techniques. This YouTube video demonstrates the techniques.

Interrupted Sutures

  • Simple
  • Vertical Mattress
  • Horizontal Mattress

Skin Closure

  • Subcutaneous
  • Deep Dermal
  • Subcuticular


  • Running
  • Running locked


  • Retention
  • Purse-string

Interrupted Sutures

The interrupted suture is a secure closure.

Simple Interrupted

Sutured chicken breast.

Vertical Mattress

Vertical mattress suture on chicken breast.

Horizontal Mattress

Horizontal mattress suture on chicken breast.
Image courtesy of Angela Chaudhari, MD.

Simple Interrupted Suture

Simple interrupted suture.
Image courtesy of Olek Remesz through Creative Commons Attribution-Share Alike license.

Vertical Mattress Suture

Vertical mattress suture.
Image courtesy of Olek Remesz through Creative Commons Attribution-Share Alike license.

Horizontal Mattress Sutures

Horizontal mattress suture.
Image courtesy of Olek Remesz through Creative Commons Attribution-Share Alike license.

Continuous Sutures

Continuous sutures are used to re-approximate tissue edges for healing by primary intention.

Running Looped Suture

Sutured chicken breast.

Most common for approximation in obstetric-gynecology surgery.

Running Locked Suture

Sutured chicken breast.
Image courtesy of Angela Chaudhari, MD.

Used for closure when hemostasis is important, such as closing a vaginal laceration.

Skin Closure Methods

Subcutaneous Sutures

Subcutaneous suture.
Image courtesy of Angela Chaudhari, MD.

Subcutaneous sutures close dead space.

Deep Dermal Sutures

Deep dermal suture.
Image courtesy of Angela Chaudhari, MD.

Deep dermal sutures are placed underneath the epidermis and may be continuous or interrupted.

Subcuticular Sutures

Suturing diagram.
Image courtesy of Olek Remesz through Creative Commons Attribution-Share Alike license.

Subcuticular sutures are placed in the dermis in a line parallel to the wound.

Other Suture Types

Retention Suture

Retention suture.
Images courtesy of Creative Commons Attribution-Share Alike.

Retention sutures are placed from the peritoneum through the entire abdominal wall. This suture is used to relieve pressure on the primary suture line and to decrease the potential wound dehiscence.

Purse String Suture

Purse string suture.
Images courtesy of Creative Commons Attribution-Share Alike.

Purse string sutures are placed around a lumen and closed like a drawstring to invert the lumena. It is a continuous running suture placed about the opening, and then drawn tight.

Optimal Suture Material for Selected Clinical Situations

Clinical Suture Justification
Tubal ligation Plain gut (0 gauge) Hemostatic but rapidly resorbed to prevent chronic inflammation and possible fistula formation
Repair of episiotomy, vaginal or perineal laceration  Chromic, Dexon, Vicryl, or Polysorb (2-0 or 3-0 gauge) 
  • Improved tensile strength compared with plain gut
  • Less inflammatory and reduces postpartum discomfort* 
Closure of fascia - low risk of wound disruption Dexon, Vicryl, or Polysorb (0 gauge)
  • More inert than plain gut or chromic
  • Improved tensile strength
Closure of fascia - high risk of wound infection and disruption (e.g., morbid obesity, DM, steroid use, preexisting infection) Maxon, PDS, Nylon, or Polypropylene (0 gauge)
  • Patients at exceptionally high risk of wound infection or disruption may require permanent sutures.
  • Patients at exceptionally high risk of wound infection or disruption may require permanent sutures. 

Note: Never use permanent sutures for possible chronic inflammatory reaction leading to dyspareunia


  1. Copeland LJ. Textbook of Gynecology, 2nd ed. Philadelphia, PA: W. B. Saunders, 2000:964–969.
  2. Greenburg J. The Use of Barbed Sutures in Obstetrics & Gynecology. Rev. Obstet Gyncol. 2010;3(3):82-91. PMID 21364859.
  3. Hartmann D. Selection of Suture Material. In: Duff P, Chair and Editor, Cowan B, Gibbons W, Guise J, Hartmann D, Look K, Schwartz D, Schink J, Wolfe H. CREOG Surgical Curriculum for New Residents.
  4. Kirk RM. Basic Surgical Techniques, 5th Edition. Churchill Livingstone, 2002.
  5. Mizell JS. Principles of abdominal wall closure. In: UpToDate, Post TW (Ed), UpToDate, Waltham, MA.
  6. Peleg D, Ahmad RS, Warsof SL et al. A randomized clinical trial of knotless barbed suture vs conventional suture for closure of uterine incision at cesarean delivery. AJOG. 2018;213(3): 343e1-343.e7.
  7. Rock J and Jones III H.W. Te Linde’s Operative Gynecology 9th ed. Philadelphia, PA: Lippincott Williams & Wilkins, 2003:233–251.

Contributing Authors

  • Farah A. Alvi, MD, MS Fellow, Minimally Invasive Gynecologic Surgery Northwestern University Feinberg School of Medicine.
  • Angela Chaudhari, MD Assistant Professor, Minimally Invasive Gynecologic Surgery Northwestern University Feinberg School of Medicine Katherine T. Chen, MD, MPH Mount Sinai Hospital New York.
  • Elise Everett, MD Associate Professor Department of Obstetrics, Gynecology, and Reproductive Sciences University of Vermont

Developed in association with the Association of Professors of Gynecology and Obstetrics.

Reaffirmed February 2021