Sutures and Needles
Suturing, also known as “stitching,” is a surgical maneuver carried out with the intent of joining together 2 selected tissues. For this purpose, the use of a needle and thread has proven to be the most cost-effective method up to modern times. Mechanical sutures (i.e., staples) are also available but are more expensive and have limited uses.
Classification of sutures
All sutures are classified according to their material as either absorbable or nonabsorbable. With absorbable sutures, the body will naturally degrade and absorb them over time. All suture materials are foreign bodies that set off an inflammatory response. Some materials are more likely to cause inflammation than others.
- Simple or chromated
- Collagen from tendons or intestines of healthy mammals
- Vicryl (braided multifilament lactide–glycoside polymer)
- PDS (monofilament polymer of polydioxanone)
- Derived from silkworms
- Nonabsorbable materials:
- Skin closure (where the sutures can be removed)
- Internal tissues and organs (where absorbable sutures do not have the sufficient strength or durability)
- Absorbable materials:
- Skin closure (sutures will not need to be removed)
- Any internal organs and tissues where the mechanical strength and durability of absorbable sutures are sufficient
Suture caliber nomenclature
- The thickest caliber of suture used in general surgery is number 1.
- The following in descending order is the number 0.
- As the caliber of the thread continues to decrease, the number of 0s increases (i.e. 2–0, 3–0, 4–0, and so on).
- The finest thread available: 11–0 for use under a surgical microscope
- Caliber selection depends largely on the location. For example:
- 3–0 and 4–0 are usually used on the extremities.
- 5–0 and 6–0 are usually used on the face.
Surgical needles classification
According to shape:
- Curved: ¼ of a circle, ⅜ of a circle, ½ of a circle, and ⅝ of a circle (require a needle holder and surgical tweezers)
According to tip (most common):
- Conventional cutting
- Reverse cutting
The size of a surgical needle is proportional to the caliber of the attached suture.
Needle holder (needle driver)
Needle holders are specialized tools used to hold the needles for suturing. Needle holders are integrated clamps that lock the needle in place for as long as required. There are 2 main types of needle holders:
- Definitive cutting instrument used to create linear wounds and dissect tissues for procedural purposes
- Reusable: metal handle and exchangeable steel blades
- Single-use: plastic handle and steel blades
- Needlelike surgical instrument that uses radio-frequency alternating current to heat tissue
- Also known as an “electric knife,” “radio knife,” or “Bovie”
- The current forms a tiny electric arc at the point, and it can:
- Cut, desiccate, or fulgurate tissue
- Sterilize the edges of the wound
- Cauterize the cut blood vessels
- Used in virtually all surgical disciplines
- Surgical instrument used to cut, ablate, or coagulate tissue
- Commonly used in:
- General surgery
- Ophthalmic surgery
- Ear, nose, and throat surgery
- Mayo scissors:
- Curved: for cutting and dissecting tissues
- Straight: for cutting textiles and sutures
- Metzenbaum scissors: for more precise cuts and delicate dissection of tissues
- Iris scissors: smaller scissors initially used for ophthalmologic and other procedures requiring finesse
Hemostasis instruments and agents
Adequate bleeding control during a surgical procedure is key for reducing the likelihood of complications and reintervention. Hemostasis can be achieved via mechanical methods, such as rudimentary pressure, or hemostats, electrocautery, or hemostatic agents.
- Hemostats (also hemostatic clamps, Pean or arterial forceps):
- Surgical tool used to control bleeding
- Many available hemostat models
- Surgical clips:
- Mechanical device used to occlude a blood vessel to achieve definitive hemostasis
- U-shaped: usually made of surgical steel or titanium
- Clips are loaded onto a special applicator, brought around the vessel, and placed one at a time by pulling on the applicator’s trigger.
- High-frequency electrical current that is conducted through the patient from an inactive electrode (in contact with the patient’s skin) and an active electrode (the pen)
- When the surgeon activates the pen, the circuit is closed and the electrical current obtained is sufficient to destroy tissues and cause coagulation.
- Induce clotting processes when applied to bleeding tissues
- Come in the form of tissues/sponges, foams, or sprays
- Examples: Surgicel, Surgifoam
Dissection and retraction instruments
Dissection instruments aid the surgeon in gaining depth in the tissues. Retraction instruments keep the surgical wound, or work area, open for further dissection.
- Indented: for avascular tissues (i.e., aponeurosis)
- Nonindented: for vascularized and delicate tissues (i.e., skin)
Graspers and clamps:
- Used to handle and to hold structures in place
- Designed to minimize trauma to the tissues
- Different graspers are suitable for different structures.
- Some examples include:
- Allis clamps
- Babcock clamps (used to handle bowel)
- Laparoscopic graspers (indented and nonindented)
Numerous instruments are available to aid with tissue dissection. Some commonly used ones include:
- Tonsil forceps
- Right-angle dissectors
- Maryland dissector (curved tip)
- Dolphin nose dissector (straight tip)
- Surgical instrument used to help with exposure
- Retractors are used to:
- Separate the edges of a surgical incision or wound
- Hold back organs that are in the way of the dissection
- Types of retraction:
- Manual: Retraction is done by handheld instruments, usually by a surgical assistant.
- Self-retaining: a mechanical device that holds tissues apart
- Manual retractors (commonly used):
- Self-retaining retractors:
- Mechanical devices used for intestinal anastomoses
- Anastomosis is accomplished with rows of titanium staples fired by the stapler.
- Some examples include:
- GIA (gastrointestinal anastomosis) stapler
- TA (thoracoabdominal) stapler
- EEA (end-to-end anastomosis) stapler
Suture and Knot Techniques
- Simple interrupted suture: Each stitch is knotted.
- Simple running (continuous) suture: Stitches are made in succession, with a knot at the very end.
- Vertical mattress:
- Also known as “far-far, near-near” stitch
- Used where wound edges are difficult to approximate
- Horizontal mattress: A simple stitch is made and reversed (parallel to the wound).
- Subcuticular suture: buried subepidermal stitches that can be running or interrupted
- Purse-string suture: running encircling suture that is usually placed around tubes to hold them in place (e.g., gastrostomy tube)
- Suture ligature:
- A suture is anchored in a structure (e.g., blood vessel).
- Then it is wrapped around the structure and tied to occlude it.
There are 2 basic types of surgical knots:
- Square knot:
- Most commonly used
- Single wraps are thrown in alternating directions.
- The number of throws depends on suture material and surgeon’s preference.
- Surgeon’s knot:
- A double-wrap is used for the 1st throw.
- Reduces loosening of the knot
- 2-handed tie: the most basic technique that needs to be mastered 1st
- 1-handed tie
- Instrument tie: Throws are made with a needle holder.
- Laparoscopic tie: a variation of an instrument tie usually done with 2 laparoscopic needle drivers
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