Basic surgical skills: incisions, sutures, knots, drains and anastomosis

Overview

Good surgical outcomes need knowledge, judgement and technical skill, plus non-technical skills such as teamwork and use of safety checklists. This chapter covers the basic techniques every house officer and trainee must know: positioning, incisions, sutures and needles, knots, closure, anastomosis, drains and diathermy.

The guiding rules are simple: gentle tissue handling, good blood supply, no tension, accurate apposition and no dead space.

Patient positioning and theatre safety

• Safe transfer and positioning is the surgeon's responsibility; protect pressure areas (heels, sacrum) in long operations.
• Positioning nerve injuries: brachial plexus, ulnar nerve (elbow) and common peroneal nerve (lithotomy stirrups at the fibular neck).
• Long lithotomy with raised legs can cause compartment syndrome.
• Diathermy plate on well-perfused muscle, away from metal implants; patient not touching metal.

Skin incisions

• Scalpel held at right angles to the skin, single clean stroke; avoid oblique (bevelled) cuts.
• Blades: No. 10 curved for most skin incisions, No. 11 pointed for arteriotomy and stab incisions (drains), No. 15 small curved for fine work.
• Pass sharps in a kidney dish, not hand to hand.

Planning an incision

1. Langer's lines (skin tension lines, the direction of dermal collagen): incisions parallel to them give the best scar.
2. Anatomy: avoid bony points and crossing flexion creases; protect nerves and vessels.
3. Cosmesis.
4. Adequate access: never sacrifice safety for a small scar.

Abdominal incisions

Open the peritoneum between two clips to avoid injuring underlying (often distended) bowel.

Suture materials

The ideal suture

Handles well, behaves predictably, holds knots, provokes little reaction, does not wick fluid or cause allergy or cancer, and is cheap. No single suture is ideal; choose by tissue and purpose.

Five properties to consider

Common sutures

Suture size

Size is graded by diameter: the more zeros, the finer the thread (6/0 is finer than 2/0). Typical choices: 10/0 microvascular and nerve, 6/0 face and distal arteries, 4/0 femoral artery, 2/0–3/0 bowel, 2/0 aorta, 1 or 0 looped for abdominal mass closure.

Needles

• Atraumatic (swaged) needles: thread embedded in the needle, no eye, smaller hole.
• Grip the needle between a third and a half of its length from the swage end, never on the swage or the point.
• Round-bodied (taper) needles separate fibres: bowel, vessels, peritoneum, soft tissue.
• Cutting needles for tough tissue (skin, fascia): conventional cutting (edge on the inner curve) and reverse cutting (edge on the outer curve, less cut-out).
• Blunt needles for abdominal closure reduce needlestick injury.
• Shape: half-circle most common (GI tract); more curve for deeper, tighter spaces; J-shaped (vagina), quarter circle (eye), compound curve (mouth). Use a needle holder rather than a hand-held straight needle.

Suture techniques

Skin sutures on the face can come out early (about 3–5 days) to avoid suture marks; areas under tension and the limbs need longer. Supporting adhesive strips help after removal.

Knots

• Must be firm, secure, small, and tightened without lifting the tissue (bed it down with a finger); avoid sawing the thread.
• Reef (square) knot: the standard, with a third throw for security.
• Granny knot: two identical throws; it slips; must be followed by a reef knot.
• Surgeon's knot: double first throw to stop slipping under tension.
• Aberdeen knot: ends a continuous suture.
• Monofilament (e.g. polypropylene) needs 6–8 throws; leave ends about 1–2 mm.

Alternatives to sutures

• Adhesive strips and tissue glue (cyanoacrylate) for clean, dry wounds under no tension (e.g. a child's forehead laceration); fibrin glue for haemostasis on liver, spleen and dura.
• Skin staples for fast closure.
• Mechanical staplers fire two staggered rows: circular (oesophagus, low rectum; check both "doughnuts" are complete), linear cutting (side-to-side anastomosis, pouches) and transverse (closing bowel ends).

Abdominal wall closure

• Mass (single-layer) closure of all layers except skin with a continuous suture.
• Material: non-absorbable (nylon, polypropylene) or slowly absorbable monofilament (PDS).
• Jenkins' rule: suture length at least 4 times the wound length (4:1). Less suture means bites too far apart or too tight (cut-out, burst abdomen); traditional bites about 1 cm deep and 1 cm apart, while newer evidence favours smaller, closer bites with a finer suture to reduce incisional hernia.
• Bring drains out through separate stab incisions, not the wound.

Principles of anastomosis

Bowel anastomosis: essentials

1. Good blood supply to both ends: pink, bleeding cut edges; ideally pulsatile bleeding from the marginal vessel and no venous congestion.
2. No tension: mobilise adequately.
3. Accurate apposition, with sutures that include the submucosa (the strongest, collagen-rich layer); inverted serosa-to-serosa contact.
4. Healthy bowel ends of similar diameter; for mismatch use side-to-side or end-to-side, or a Cheatle split (cut along the antimesenteric border of the narrower end).
5. Avoid contamination: soft (atraumatic) clamps across the bowel, not across the mesentery.
6. Close the mesenteric defect to prevent internal hernia.

• Single-layer extramucosal (interrupted or continuous) and two-layer anastomoses give similar results.
• Bites roughly 3–5 mm in depth with similar spacing, 2/0–3/0 absorbable suture (polyglactin or PDS) on a round-bodied needle.
• Do the difficult mesenteric corner first, finish at the antimesenteric side.
• Staplers are preferred where access is difficult (oesophagus, low rectum) or speed matters.

Vascular anastomosis

• Must be watertight immediately, with a smooth intimal surface (reduces thrombosis and embolism).
• Non-absorbable monofilament (polypropylene) on a round-bodied needle, double-ended; knot with 6–8 throws.
• Suture from inside to outside on the downstream (distal) side so plaque and intima are pinned down and no intimal flap forms.
• Size: 2/0 aorta, 4/0 femoral, 6/0 popliteal and distal; microvascular down to 10/0.
• Handle vessels with atraumatic forceps (e.g. DeBakey); release the distal clamp first before the final knot to flush air and debris.
• A transverse arteriotomy narrows less than a longitudinal one; use a vein patch if narrowing is a risk.

Drains

Purpose: remove fluid or air (blood, serum, pus, bile, urine, chyle, pancreatic or intestinal juice); warn of bleeding or leakage; create a track. Prophylactic in elective surgery, therapeutic for established collections.

• Place through a separate incision (through the wound raises infection and hernia risk).
• Evidence shows routine drains are not needed after many gastric, small bowel, appendix and biliary operations; use is often surgeon preference. ERAS pathways discourage routine drains.
• Remove as soon as the purpose is met: most stop working within a week and a drain left in becomes a foreign body.

• Chest drain: check the fluid level swings with breathing; remove with the patient holding breath (Valsalva) and tie the purse-string.
• Release suction before removing a suction drain.
• Image-guided (ultrasound/CT) pigtail drains are first-line for many abdominal collections.
• T-tubes are made of latex to provoke a fibrous track.

Diathermy (electrosurgery)

High-frequency alternating current produces heat where current density is highest.

• Cutting: continuous waveform; tissue water boils into steam.
• Coagulation: interrupted (pulsed) waveform; protein denaturation seals vessels.
• Fulguration: high-voltage sparks over a surface, causing charring.
• Blend: mixture of cut and coag.

Complications

• Burns at the plate: poor contact (hairy skin, scar, bony site, plate peeling off).
• Alternate site burns: patient touching metal (table parts, stirrups, drip stands), ECG electrodes.
• Channelling: current through a narrow pedicle (penis, testis–cord) heats the pedicle itself → use bipolar.
• Fire: pooled alcohol skin preparation, bowel gases (avoid with mannitol bowel preparation), oxygen-rich drapes.
• Pacemakers: interference or inhibition; use bipolar, keep plate far from the device, have the anaesthetist prepared (magnet, reprogramming).
• Laparoscopic: direct coupling, faulty insulation, burns out of view, retained heat in the tip, capacitance coupling (avoid hybrid metal–plastic ports).

Quick revision

• Incise along Langer's lines; ellipse 3:1; open peritoneum between clips.
• Monofilament = smooth, lower infection; braided = easy knots but harbours bacteria.
• Vessels: polypropylene, inside-out downstream; biliary/urinary: absorbable only.
• Round-bodied needles for bowel and vessels; cutting for skin and fascia.
• Reef knot standard; 6–8 throws for monofilament.
• Mass closure, slowly absorbable or non-absorbable monofilament, 4:1 suture to wound length.
• Anastomosis: blood supply, no tension, include submucosa, close the mesentery.
• Drains through separate stab; remove early (thyroid 24 h, mastectomy 5 days, T-tube 10 days).
• Bipolar diathermy for penis, digits, cord and pacemakers.

Written by The House Job from standard references (Bailey & Love's Short Practice of Surgery, 27th edition).

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