2.4 Suturing & Wound Closure

Absorbable vs. Non-Absorbable Suture

Suture is the material used to ligate vessels and reapproximate (sew together) tissue. The first major distinction is whether the body breaks it down.

• Absorbable suture is digested by enzymes or hydrolysis and disappears over days to months. It is used in tissue that heals quickly or where permanent material is undesirable (deep layers, bowel, bladder, subcutaneous tissue). Examples: surgical gut (plain and chromic), Vicryl (polyglactin 910), Monocryl (poliglecaprone), PDS (polydioxanone).
• Non-absorbable suture retains strength indefinitely and is either removed (skin) or remains permanently (vascular anastomosis, tendon, hernia mesh). Examples: silk, nylon (Ethilon/Dermalon), polypropylene (Prolene), polyester (Ethibond), stainless steel.

Suture Sizing and Filament Type

Suture size describes the strand's diameter using a zero (USP) scale. As the number of zeros increases, the suture gets smaller: from large to small the order runs 2, 1, 0, 2-0, 3-0, 4-0, 5-0, 6-0, 7-0... Thus 2-0 ("two-oh") is larger than 5-0, and 7-0 is finer still — used for microsurgery and small vessels. Larger sizes (1, 2) close fascia and hold heavy tissue; finer sizes (5-0 to 7-0) close skin on the face or repair tiny vessels.

The second property is filament construction:

• Monofilament is a single smooth strand. It has low tissue drag, resists harboring bacteria, and is preferred in contaminated or delicate tissue, but it has memory and can be harder to tie. Examples: nylon, Prolene, PDS, Monocryl.
• Multifilament (braided) is many strands twisted or braided together. It handles and ties easily with good knot security but the interstices can wick fluid and harbor microorganisms (capillarity). Examples: silk, Vicryl, Ethibond.

The CST loads suture so the surgeon can sew immediately and keeps track of every needle for the count.

Needles, Stapling, and Other Closure Devices

Surgical needles have three parts: the point (tip), the body, and the swage/eye (attachment end). A swaged (atraumatic) needle has the suture pre-attached to an eyeless end so only a single strand passes through tissue, minimizing trauma; eyed (traumatic) needles require threading and pull a doubled strand.

Needle point type is matched to tissue:

• Cutting needle (triangular point) — for tough tissue such as skin and fascia.
• Taper (round-body) needle — for soft tissue such as bowel, muscle, peritoneum, and vessels that would tear with a cutting point.
• Blunt point — for friable tissue such as liver and kidney.

Needle curvature is described in fractions of a circle (1/4, 3/8, 1/2, 5/8); deeper, more confined spaces (such as the pelvis) call for a more curved (1/2 or 5/8) needle, while superficial skin closure uses a shallower 3/8 curve. A straight (Keith) needle is used for some skin and purse-string sutures. Suture also comes in standard package presentations the CST should recognize: a single-armed suture has one needle; a double-armed suture has a needle swaged onto each end (common in vascular anastomoses).

Ligatures (reels/ties) come without needles for tying off vessels, and control-release ("pop-off") needles detach with a straight tug for rapid interrupted suturing — but every detached needle must still be accounted for in the count.

Alternatives to hand suturing include surgical staples (skin and internal anastomosis/resection with linear or circular staplers), ligating clips (Hemoclips, Weck clips) for vessels, surgical adhesives/tissue glue (cyanoacrylate) for low-tension skin, and adhesive strips (Steri-Strips) for superficial closure. The CST anticipates the closure method for each layer and ensures the matching device, suture, and needle are loaded and counted.

Suturing Techniques and Layered Closure

The surgeon reapproximates tissue with recognizable stitch patterns, and the CST anticipates the material each needs:

• Continuous (running) suture — one strand sewn in a series of stitches and tied at each end; fast, distributes tension, but a single break can loosen the whole line.
• Interrupted suture — each stitch is tied and cut individually; slower but more secure, since one failed knot does not compromise the rest.
• Subcuticular — a buried continuous stitch in the dermis for a cosmetic closure with no external marks.
• Retention sutures — heavy, widely placed reinforcing stitches (often through bolsters) that take tension off the primary closure in high-risk abdominal wounds.
• Purse-string — a circular stitch drawn tight to close or invert a stump (e.g., appendiceal).

Layered (anatomical) closure rebuilds the wound from the inside out: peritoneum, fascia, muscle, subcutaneous tissue, then skin, matching suture to each layer. Fascia, which holds the most tension, gets strong long-lasting suture (PDS, Prolene, or a heavy absorbable); subcutaneous tissue gets a finer absorbable; skin gets fine non-absorbable, staples, or adhesive.

Wound healing is described as first intention (clean, approximated edges healing directly), second intention (an open wound granulating in from the base), or third intention/delayed primary closure (left open initially, then sutured once contamination is controlled). Knowing the planned closure lets the CST have the right suture, needles, and counts ready at the right moment.