The selection of suture to approximate wounds to stimulate healing by primary intention is decided by medical practitioners based on a few factors. In general, their choice of suture and needle is made based on the combination of both their medical training and personal experiences. Irrespective of their choices, the aim of utilizing a needle and suture is similar. Surgeons have to take into consideration important factors that affect wound healing such as selecting a material that is appropriate for the wound bed, can lower the infection rate and improve the potential aesthetic of the final scar.
In this article, readers will be introduced to the broad characteristics of sutures that affect a surgeon's decision on their time of usage in the medical field.
A generally accepted classification of suture size is the USP (United States Pharmacopeia) system. The numbering system ranges from USP size 4 ("number four") to USP size 10-0 ("ten o").
- For a simpler explanation, students can consider that sutures with USP size 0 and upwards fall under the positive number scale. Therefore, a suture with a USP size Three (3) will have a bigger diameter and metric gauge than a suture with USP size One (1).
- Likewise, students can think of USP sizes with zero at the back, for instance, 2-0 or 3-0 to fall under the negative number scale. That would indicate that suture with USP size 7-0 will have a smaller diameter and metric gauge than USP size 1-0. In terms of their application, 7-0 will commonly be used for a facial laceration in plastic surgery while 1-0 will be used to close a midline laparotomy.
Multi- Vs. Monofilament Suture
As their name suggests, multifilament sutures are made by braiding several strands of filamented materials together while monofilament suture consists of a single strand of filament. As a direct result of their difference in structure, multifilament sutures have more tensile strength and flexibility than its counterpart.
However, monofilament sutures have the advantage of reduced resistance on tissue insertion and harbor fewer bacteria exposure. Monofilament sutures are more commonly used in the setting of vascular surgeries because they are easier to manoeuvre while multifilament sutures are favorable for intestinal surgeries.
Absorbable Vs. Non-Absorbable Suture
The main difference between an absorbable (e.g Monocryl, Vicryl, PDS) and a non-absorbable (e.g nylon (Ethilon, silk, steel, Prolene) is that an absorbable suture will be broken down through hydrolysis and enzyme degradation with time depending on the suture material and wound type. In general, skin approximation of a clean surgical wound would normally use absorbable suture. In the case of non-absorbable suture, they can be used to approximate skin wounds with less reactivity and be removed at a later date or be applied in vessel, bowel or tendon repair where they will be retained.
Synthetic Vs. Natural Suture
Natural Suture Synthetic Suture
Suture materials, both absorbable or non-absorbable can be made from either synthetic or natural raw origin. Natural sutures are made from natural sources such as silk and catgut while synthetic sutures are composed of human-made material such as nylon. Natural sutures tend to provoke a higher rate of tissue reaction while synthetic sutures are more predictable in terms of their reactivity and pattern of tensile strength loss.
A barbed suture is a suture with barbs on them that can hold wound borders together and distribute tension along the whole extent of a suture without the necessity of having knots to secure the wound. Therefore, the usage of the barbed suture would indicate reduced knot-related complications and improved efficiency of wound closure with reduced suturing time and overall operating time.