Module 4 · Intraoperative Procedures I: The Sterile Team
Lesson 4.4 — Wound Closure
Wound closure is where suture knowledge, surgical anatomy, and scrub technique converge in a single high-stakes sequence. The CST exam tests suture selection, needle type, sizing logic, stapler function, drain purpose, and the principles of wound healing — and it tests them by scenario, not simple recall.
📋 NBSTSA Blueprint: Domain I-B · Intraoperative Procedures · Tasks: Prepare and pass suture and needles · Anticipate wound closure sequence · Assist with wound closure and dressing application
🎯 High-Yield Topics — What Gets Tested
Absorbable vs. non-absorbable — when each is used · USP sizing: more zeros = smaller · Monofilament vs. multifilament — infection risk · Swaged needle — permanently attached · Cutting vs. reverse cutting vs. taper point needle · Which needle for which tissue · Suture by layer: peritoneum, fascia, subcutaneous, skin · Common sutures by name: Vicryl, Chromic, PDS, Prolene, Nylon, Silk, Monocryl · GIA vs. TA vs. EEA stapler — what each does · Primary vs. secondary vs. tertiary (delayed primary) wound healing · Drain types: Penrose vs. Jackson-Pratt vs. Hemovac · Drain secured with silk · Dressing layers: contact, absorbent, outer wrap
1. Wound Healing — Three Types
Before selecting a closure method, the team must determine how the wound is going to heal. The type of wound healing drives every decision that follows — suture choice, drain placement, dressing selection.
Primary Intention (First Intention)
Clean wound — closed immediately
The wound edges are approximated (brought together) and closed at the time of surgery. Clean surgical incisions — laparotomy, cholecystectomy, joint replacement — heal by primary intention. All wound closure techniques (suture, staples, adhesive) produce primary intention healing. The goal is immediate approximation with minimal scarring.
Secondary Intention (Granulation)
Contaminated/infected — left open
The wound is left open and allowed to heal from the bottom up through granulation tissue formation, contraction, and re-epithelialization. Used when infection risk is too high to close — infected wounds, heavily contaminated wounds (bowel perforation), abscess cavities, pressure injuries. Heals slowly; significant scarring.
Tertiary Intention (Delayed Primary Closure)
Contaminated — closed after delay
The wound is initially left open for several days to allow debridement, infection control, or edema resolution — then surgically closed. Used for traumatic wounds, blast injuries, or wounds with gross contamination where immediate closure would trap infection. Combines the benefits of open wound management with eventual formal closure. Also called delayed primary closure (DPC).
2. Suture Classification — The Four Axes
Every suture question on the CST exam can be answered by moving through four classification axes: absorbability, origin, structure, and size. Knowing where a suture falls on each axis tells you when and where to use it.
📝 Knowledge Check 1: The surgeon is closing the peritoneum of an abdominal incision. Which suture characteristic is MOST important when making this selection?
A. Non-absorbable — the peritoneum requires permanent support
B. Absorbable — the peritoneum heals and the suture does not need to remain permanently
C. Non-absorbable monofilament — to prevent infection in the deep layers
D. The largest available gauge to ensure the peritoneum does not reopen
Reveal Answer
✅ Correct Answer: B
Deep tissue layers including the peritoneum, fascia, muscle, and subcutaneous tissue are closed with absorbable suture. The peritoneum heals within weeks — leaving a permanent suture here would serve no purpose and would create a foreign body response. Option A is wrong because non-absorbable suture is used for structures requiring long-term support (fascia in mass closure) or for skin removal. Option D is wrong — the largest available gauge would create unnecessary tissue damage; the appropriate size is selected to match tissue strength requirements, not to compensate for technique. The most commonly used suture for peritoneal closure in practice is 0-Vicryl or 0-PDS.
3. Common Sutures by Name — The Exam’s Tested List
The exam identifies sutures by their generic name and/or brand name. You must know both — a question may say “polyglactin 910” and the answer choices say “Vicryl.” Know the generic-to-brand mapping cold.
Absorbable Sutures
| Brand | Generic Name | Structure | Key Facts & Use |
|---|---|---|---|
| Plain Gut | Surgical gut / catgut | Natural / twisted | Absorbed in 7–10 days; high tissue reactivity; limited use today; mucous membrane, superficial layers |
| Chromic Gut | Chromic catgut | Natural / twisted | Treated with chromium salts — absorbed in 21–28 days; slower than plain gut; less reactive than plain gut; mucous membranes, bladder, vaginal cuff, some GI work |
| Vicryl | Polyglactin 910 | Synthetic / braided | Most widely used absorbable suture; absorbed in 56–70 days; used for peritoneum, fascia, subcutaneous tissue, bowel anastomoses; purple or undyed |
| Monocryl | Poliglecaprone 25 | Synthetic / mono | Smooth, pliable; absorbed in 91–119 days; minimal tissue reaction; excellent for subcuticular (hidden) skin closure and fine subcutaneous work |
| PDS | Polydioxanone | Synthetic / mono | Longest lasting absorbable — retains strength for 4–6 months, absorbed by 6 months; used for fascia, abdominal wall mass closure, pediatric cardiac; purple color |
Non-Absorbable Sutures
| Brand | Generic Name | Structure | Key Facts & Use |
|---|---|---|---|
| Silk | Surgical silk | Natural / braided | Excellent handling and knot security; loses tensile strength over 1 year; highest tissue reactivity of non-absorbables; used to secure drains, ties around vessels, GI procedures; black |
| Nylon (Ethilon) | Polyamide | Synthetic / mono | Inert, minimal tissue reaction; standard skin closure suture; also nerve repair and tendon surgery; black or blue; requires multiple knots due to memory |
| Prolene | Polypropylene | Synthetic / mono | Extremely inert; does not degrade; used for vascular anastomoses (aorta, coronary), hernia mesh fixation, subcuticular skin closure; blue; high memory (difficult to handle) |
| Ethibond | Polyester | Synthetic / braided | Strong, excellent knot security; used for sternal closure, tendon repair, valve annulus repair in cardiac surgery; green or white |
| Stainless Steel | Surgical steel wire | Metal / mono or multi | Maximum tensile strength; minimal tissue reaction; sternal closure after cardiac surgery; tendon repair; retention sutures; requires wire twister or needle driver |
💡 Drain Secured With Silk: The go-to suture for securing a surgical drain to the skin is silk — its superior handling and knot security make it ideal for this purpose even though it is the most reactive non-absorbable. The exam tests this directly: “Which suture material is most commonly used to secure a drain?” Answer: silk.
4. Surgical Needles — Type and Tissue Match
The needle is chosen to match the tissue — not the suture. A needle that is too traumatic for the tissue creates larger holes than necessary; a needle that is too delicate cannot penetrate tough tissue. Swaged needles (eyeless, with suture permanently attached) are standard in surgery — they eliminate the tissue drag of threading a needle and are counted individually on the needle board.
| Needle Type | Tip Shape | Tissue & Use |
|---|---|---|
| Taper Point (Round Bodied) | Smooth round point, no cutting edges | Spreads tissue rather than cutting it. Used for soft, delicate tissue: bowel, peritoneum, muscle, vessels, fascia. The atraumatic choice for internal layers. |
| Conventional Cutting | Triangular tip — cutting edge on the inside curve | Cuts through tough tissue. Used for skin, fascia, tendon. The inside cutting edge can cut toward the wound — risk of tissue tear if pulled toward the incision edge. |
| Reverse Cutting | Triangular tip — cutting edge on the outside curve | Preferred for skin closure. The outside cutting edge cuts away from the wound edge, reducing the risk of suture cutting through tissue. Stronger than conventional cutting. |
| Blunt Point | Rounded blunt tip — no sharp point | Used for friable tissue — liver, spleen, kidney. Also used in settings where needlestick risk is high (mass closure, blunt fascial closure). Cannot penetrate tough tissue. |
| Spatula (Side-Cutting) | Flat, spatula-shaped — cuts sideways | Ophthalmic surgery — designed to pass through the layers of the eye (cornea, sclera) without penetrating too deeply. Rarely tested on the CST exam but should be recognized. |
💡 Needle Curvature: The most common needle body shapes are 3/8 circle (skin, superficial tissue — easy to handle in open spaces), 1/2 circle (deep tissue — better control in confined spaces), and straight needles (hand suturing, subcuticular, tendon). The exam rarely specifies curvature in isolation but pairs it with tissue type: 3/8 circle cutting = skin; 1/2 circle taper = deep/visceral.
📝 Knowledge Check 2: During skin closure the surgeon requests a needle that will resist cutting through the skin edge. Which needle type should the scrub tech prepare?
A. Taper point — atraumatic, preferred for skin
B. Conventional cutting — cuts through the skin easily
C. Reverse cutting — the outer cutting edge protects the wound edge from tissue tear
D. Blunt point — used for skin closure when infection risk is high
Reveal Answer
✅ Correct Answer: C
The reverse cutting needle has its cutting edge on the outside of the curve — meaning it cuts away from the wound edge rather than toward it. This makes it the preferred needle for skin closure because it greatly reduces the risk of the suture pulling through (cutting through) the wound edge. The conventional cutting needle’s inside edge cuts toward the wound, creating a risk of cheese-wiring through skin if any tension is placed on the suture. Taper point needles are designed for soft internal tissue and cannot effectively penetrate the skin. Blunt points are for friable tissue like liver, not skin.
5. Closure by Layer — The Scrub Tech’s Sequence
The CST must anticipate the closure sequence and have the correct suture ready before the surgeon asks. Each layer has a specific suture profile that matches its anatomy, healing requirements, and mechanical demands.
Laparotomy Closure — Layer by Layer
| Layer | Typical Suture | Needle | Notes |
|---|---|---|---|
| Peritoneum | 0-Vicryl or 0-Chromic | Taper point | Absorbable; some surgeons do not close peritoneum separately (preference-dependent) |
| Fascia | #1 or 0-PDS or Nylon | Taper or blunt | Requires strong, slowly absorbed (PDS) or permanent (Nylon) suture. Mass closure combines fascia and peritoneum in one layer. |
| Subcutaneous | 2-0 or 3-0 Vicryl | Taper point | Absorbs dead space to reduce seroma or hematoma formation beneath the skin |
| Skin | 3-0 or 4-0 Nylon or staples or Monocryl (subcut) | Reverse cutting (if suture) | Non-absorbable (Nylon) removed 5–14 days postop; subcuticular Monocryl does not require removal |
6. Surgical Staplers — Three Systems the Exam Tests
Skin Stapler
Disposable device that applies individual stainless steel staples to close the skin. Faster than sutures for long incisions. The assistant holds the wound edges together while the surgeon applies staples. Staple removal (at 5–14 days) requires a staple remover — not scissors. Titanium or stainless steel — will appear on postoperative X-ray.
📝 Knowledge Check 3: After firing the EEA stapler during a low anterior resection, the scrub tech and surgeon inspect the tissue rings. One donut has a gap in the staple line. What does this indicate?
A. This is normal — donuts rarely come out perfectly complete
B. The anastomosis may be incomplete — the surgeon must assess and potentially reinforce or redo the anastomosis
C. Discard the donuts — they are surgical waste and do not provide clinical information
D. Irrigate the anastomosis site and continue — the staple ring will seal over time
Reveal Answer
✅ Correct Answer: B
Inspecting the tissue donuts after firing the EEA circular stapler is a mandatory step. Both donuts must be complete, intact rings of tissue. A gap or incomplete ring indicates that the anastomosis staple line is also incomplete — meaning bowel contents can leak at that point. The surgeon must be notified immediately and the anastomosis assessed for a potential anastomotic leak, which may require reinforcing sutures or takedown and re-anastomosis. The scrub tech’s role is to present the donuts for inspection and alert the team if they are not complete. Never discard the donuts before inspection.
7. Surgical Drains — Types, Purposes, and Exam Rules
⚠️ Critical Drain Rules — Tested Directly
Drains are brought out through a separate stab incision — not through the primary wound. This prevents disruption of the wound closure and reduces infection at the primary incision.
Drains are secured with silk suture — silk’s superior knot security prevents the drain from being inadvertently pulled out.
Drain tubing is counted as a miscellaneous item. If a drain segment is used intraoperatively (e.g., a Penrose used as a vessel loop for retraction), it must be counted. The entire drain must be accounted for at closure.
8. Surgical Dressings — Three Layers
The final dressing is applied at skin closure — while the patient is still on the OR table and the sterile field is intact. The CST prepares dressing materials and may assist with application. The exam tests the three-layer dressing concept and which material belongs in each layer.
📝 Knowledge Check 4: The surgeon requests a suture to secure a Jackson-Pratt drain to the skin. Which suture should the scrub tech pass?
A. 4-0 Vicryl — absorbable, so the drain can be removed without suture removal
B. 2-0 Silk — non-absorbable with excellent knot security; standard drain-securing suture
C. 4-0 Prolene — vascular suture, appropriate for any non-absorbable need
D. 3-0 Nylon — standard skin closure suture appropriate for drain fixation
Reveal Answer
✅ Correct Answer: B
Silk suture is the standard material for securing surgical drains. Its braided structure provides excellent knot security — critical for a suture that must reliably hold a drain in place during patient movement and dressing changes. The 2-0 size provides adequate strength at the skin level. Option A (Vicryl) is wrong because absorbable suture would dissolve before the drain is ready for removal, causing the drain to fall out prematurely. Option C (Prolene) and D (Nylon) are non-absorbable monofilaments — they lack silk’s knot security and handling characteristics, making them suboptimal for drain fixation. This is a direct, frequently tested CST exam fact: silk secures drains.
⚡ Rapid Review — Wound Closure High-Yield Facts
Module 4 Complete
Lessons 4.1 through 4.4 cover the entire sterile team’s intraoperative toolkit: counts, draping, instruments, and wound closure. Together these four lessons represent a substantial portion of the 68-item Intraoperative Procedures domain. Module 5 takes you deeper — hemostasis, medications on the sterile field, surgical emergencies, and specimen management.
Next: Module 5 · Lesson 5.1 — Hemostasis