Sutures and Suture Materials
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Direct answer
Sutures are classified by absorbability, filament structure and origin: absorbable materials such as polyglactin (Vicryl), polydioxanone (PDS) and poliglecaprone (Monocryl) lose tensile strength over weeks, while non-absorbables such as polypropylene, nylon, silk and steel persist. Monofilament sutures slide through tissue with less infection risk because they offer bacteria no interstices, whereas braided sutures handle superbly but harbour organisms within their strands. Selection matches tissue healing time and biomechanics — rapidly absorbing material for mucosa and subcutaneous tissue, slow-absorbing PDS for fascia, and the least reactive non-absorbables such as polypropylene for vascular anastomoses and hernia repair.
What you must remember
- Absorbable synthetics: polyglactin retains useful strength for a few weeks and is absorbed in about 2 months; PDS is the longest-lasting absorbable (support for months) and suits contaminated fascial closure; catgut is natural and largely replaced.
- Non-absorbables: silk handles excellently but is the most reactive of the group; polypropylene and nylon are monofilaments with minimal reactivity suited to skin, vessels and mesh fixation; stainless steel is used in sternotomy and bone.
- Braided versus monofilament: braided ties and knots are easier but wick infection; monofilaments are safer in contaminated fields but need more throws.
- Needle points: cutting needles for skin and tough tissue, round-bodied needles for liver, kidney and bowel anastomosis, taper-cut for tough-to-penetrate viscera.
- Sizes run inversely — the higher the number, the finer the suture: 1, 0, 2-0 down to 10-0 for microvascular and ophthalmic work.
- The golden rule of tying: approximate the edges without strangulating them; excessive tension causes ischaemic necrosis and dehiscence.
- Shorter skin suture life reduces scarring, hence early removal on the face and the use of absorbable subcuticular sutures where possible.
Common confusion
Students confuse 'absorbable' with 'rapidly weakening'. Polyglactin and PDS are both absorbable, but their strength profiles differ enormously, so using polyglactin in a high-tension fascial closure of a contaminated abdomen invites dehiscence. The second confusion is reactivity versus absorbability — silk is non-absorbable yet one of the most tissue-reactive materials, while polypropylene is non-absorbable and among the least reactive, which is exactly why one is avoided in vascular work and the other chosen.
Exam-focused takeaway
NEET-PG asks these as property-matching one-liners: which suture for bile duct anastomosis or tendons, which is safest in infected wounds (a monofilament such as PDS or nylon), which suture is avoided with silk in contaminated fields, and the meaning of gauge numbers. Learn each named material with its brand-generic pair and one signature use — Vicryl for subcutaneous tissue, PDS for abdominal fascia, Monocryl for subcuticular skin, Prolene for vessels and mesh, silk for secure ligation in clean fields.
Frequently asked questions
Which suture is preferred for closing contaminated abdominal fascia?
A delayed-absorbable monofilament such as polydioxanone, because it resists infection better than braided material and supports the fascia long enough for healing.
Why are braided sutures avoided in infected wounds?
Bacteria colonise the interstices between braided filaments where immune cells cannot reach, so braided materials are associated with persistent wound infection and suture sinuses.
What is the difference between cutting and round-bodied needles?
Cutting needles have sharpened edges to penetrate tough skin and fascia, while round-bodied needles bluntly part soft, fragile tissue such as bowel wall and liver without cutting.
How are suture sizes interpreted?
Sizes are inverse: 0 is thicker than 2-0, which is thicker than 4-0; fine microvascular work uses 8-0 to 10-0, and heavy fascial closure uses 0 or 1.
What happens if sutures are tied too tightly?
Excessive tension strangulates the tissue within the loop, causing ischaemia, necrosis, increased scarring and a higher risk of dehiscence rather than a stronger repair.