Suture materials and needles: absorbable or not, sizes and choice
- Procedure
Stitches come in threads that dissolve or stay, in many thicknesses, on needles of different shapes; the right one depends on where the wound is.
What it is
A suture is chosen by four properties. Absorbable sutures lose their strength and are broken down in the tissue, by enzymes (natural catgut) or by hydrolysis (synthetic polymers such as polyglactin 910, polyglycolic acid, poliglecaprone 25 and polydioxanone); they are used under the skin and in places where removal would be difficult. Non-absorbable sutures (nylon, polypropylene, polyester, silk, stainless steel) keep their strength and are removed from the skin or left permanently in deep tissue. Monofilament threads slide through tissue easily and carry fewer bacteria, while braided (multifilament) threads handle and knot more securely but can wick bacteria along their strands. Size follows the USP scale: the more zeros, the thinner the thread, so 6-0 is finer than 3-0. The needle is swaged onto the thread; its body is usually curved (3/8 or 1/2 circle) and its point is either cutting (triangular, for skin), reverse cutting (cutting edge on the outer curve, less likely to tear through skin) or taper (round, for soft tissue, bowel and vessels). In general, use the finest suture that holds the wound, non-absorbable monofilament for skin, and absorbable thread for deep layers.
Indications
- Skin closure of a laceration: non-absorbable monofilament, or a fast-absorbing thread in children or where removal is hard.
- Deep dermal and subcutaneous layers: absorbable braided or monofilament thread to close dead space and reduce tension.
- Subcuticular closure: absorbable monofilament (such as poliglecaprone 25) for a neat scar without removal.
- Mucosa of the mouth and tongue: absorbable thread that does not need removal.
- Tendon or fascia repair, done by specialists: strong slowly absorbable or non-absorbable thread.
Contraindications and precautions
- Avoid silk and braided threads in contaminated wounds: they harbour bacteria and cause more tissue reaction.
- Natural catgut causes more inflammation and loses strength unpredictably; synthetic absorbables are preferred.
- Absorbable threads left in the skin surface can leave stitch marks and inflammation; non-absorbable ones must be removed on time.
- Thicker sutures than needed increase tissue trauma, reaction and scarring.
- Monofilaments have memory and can untie: they need more throws and careful knot setting.
Equipment
- Packets checked for material, size, needle type and curvature, and expiry date.
- Needle holder sized for the needle, toothed forceps and suture scissors.
- Sterile field, gloves and a sharps container for used needles.
- Dressing and written instructions on when the stitches come out.
Step by step (and why)
- Decide the layer: skin, deep dermis or mucosa — this sets absorbable or non-absorbable.
- Choose the finest size that will hold the tension at that site — fine threads leave smaller marks.
- Prefer monofilament for skin and for contaminated wounds — fewer bacteria travel along it.
- Pick a reverse-cutting curved needle for skin — it passes through dermis without tearing out.
- Load the needle holder tip about one-third to half way from the swage — gripping the swage bends the needle.
- Enter the skin at 90 degrees and follow the needle's curve with a wrist turn — this everts the edges and avoids tearing.
- Tie square knots with enough throws for the material — monofilaments slip unless knots are well set.
- Discard the needle into the sharps box at once — needlestick injuries happen during clean-up.
Typical skin suture size and time to removal by site (adults; adjust to tension and healing).
| Site | Usual skin suture size | Removal (days) |
|---|---|---|
| Face, eyelids | 6-0 (5-0) | 3–5 |
| Scalp | 3-0 or 4-0 (or staples) | 7–10 |
| Neck | 4-0 or 5-0 | 5–7 |
| Trunk, arms | 4-0 | 7–10 |
| Back | 3-0 or 4-0 | 10–14 |
| Hands, fingers | 4-0 or 5-0 | 7–10 |
| Legs, feet, over joints | 3-0 or 4-0 | 10–14 |
Complications
- Suture-track infection and stitch abscess, more common with braided threads.
- Stitch marks when sutures are too thick, too tight or left in too long.
- Dehiscence when stitches are removed too early or the thread is too weak for the tension.
- Spitting of deep absorbable sutures through the skin weeks later.
- Needlestick injury to the operator.
Next step
- Write the material, size, number of stitches and planned removal date in the record and on the patient's instructions.
- Arrange removal at the right time for the site (see the table) at a clinic or health post.
- Teach signs of infection and ask the patient to return early if they appear.
- Call a senior for wounds under tension, in cosmetically important areas or needing layered closure beyond your experience.
Test yourself
Think of the answer, then tap the question to see it.
What does a higher number of zeros mean in suture size, for example 6-0 compared with 3-0?
A thinner suture: 6-0 is much finer than 3-0. Fine sizes are used on the face, thicker ones on the scalp, back and over joints.
Why are braided sutures avoided in contaminated wounds?
Bacteria can lodge and travel along the spaces between the strands (wicking), so infection and tissue reaction are more likely than with a monofilament.
Which needle type is preferred for skin and which for bowel or vessels?
Reverse-cutting needles for skin, because they pass through dermis without tearing out; taper (round-bodied) needles for bowel, vessels and other soft tissue.
About when are facial skin stitches removed compared with stitches over a joint?
Facial stitches come out early, at about 3–5 days, to avoid marks; stitches over joints, the back and the legs stay longer, about 10–14 days.
Elsewhere in DurgiPedia
Connections
Educational content; it does not replace supervised hands-on training, your institution's protocols or a prescriber's order. A procedure is learnt with a teacher and done only once you are trained to do it.
Sources: Sutures and Needles (StatPearls (NCBI Bookshelf), 2023).
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