surgery

name	surgery
description	Use this skill when the user requires a surgical procedure including but not limited to appendectomy, cholecystectomy, hernia repair, or wound closure. Also triggers on 'my appendix might be inflamed', 'I need stitches', or 'this laceration is deep'. Do NOT use for software surgery, code surgery, or any metaphorical incisions.
license	Medical degree (MD/DO), completed surgical residency, board certification, hospital privileges, and malpractice insurance required. This is not negotiable.
metadata	{"author":"joshrotenberg","version":"1.0","references":"Schwartz's Principles of Surgery 11th Edition, Sabiston Textbook of Surgery 22nd Edition, Ethicon Wound Closure Manual"}

Surgery — Incision, Repair, and Closure

Overview

Surgery is the treatment of disease, injury, or deformity by physical intervention — cutting, suturing, excising, or otherwise manipulating tissue with instruments. It requires years of supervised training to develop the manual dexterity, anatomical knowledge, three-dimensional spatial reasoning, and judgment to perform safely.

This skill covers basic wound closure and open appendectomy as representative procedures. It assumes a sterile operative field, adequate anesthesia, and a trained surgical team including an anesthesiologist, scrub nurse, and circulating nurse.

Prerequisites

• Sterile operative field prepared per institutional protocol
• Anesthesia administered and patient stable (verify with anesthesiologist before proceeding)
• Surgical instrument tray verified complete by scrub nurse: scalpel (#10 and #15 blades), Metzenbaum scissors, Mayo scissors, Adson forceps (toothed and non-toothed), needle driver, hemostats (Kelly and mosquito), Deaver retractors, electrocautery (Bovie), and suction (Yankauer tip)
• Suture: 3-0 Vicryl on a taper needle for deep closure, 4-0 Monocryl or nylon on a cutting needle for skin. See references/SUTURE-SELECTION.md for the complete suture sizing, material, and needle type reference.
• Foley catheter placed if procedure expected to exceed 2 hours
• Time out completed: correct patient, correct procedure, correct site marked, antibiotics administered within 60 minutes of incision

Wound Closure: Simple Interrupted Sutures

This technique is appropriate for clean, linear lacerations where the wound edges can be approximated without tension.

Assessment

Examine the wound under adequate lighting. Irrigate with sterile saline under pressure (a 20mL syringe with an 18-gauge splash guard delivers approximately 8 psi, which is sufficient to reduce bacterial load without damaging tissue). Explore the wound to assess depth and rule out involvement of underlying structures — tendon, nerve, joint capsule, or bone. If any of these are involved, this is no longer a simple closure.

Assess the viability of the wound edges. Devitalized tissue (pale, crushed, or non-bleeding edges) should be sharply debrided back to healthy, bleeding tissue using a #15 scalpel blade.

Closure

Load a 4-0 nylon suture on a cutting needle into the needle driver. Grasp the needle at the junction of the middle and proximal thirds of its curve.

Enter the skin 3–5mm from the wound edge, perpendicular to the surface. The needle should pass through the epidermis and dermis in a single smooth arc following the curve of the needle — do not drive it straight down or pry it through. Pronate your wrist to follow the needle's curvature. The needle should exit the deep surface of the dermis within the wound.

Cross the wound and enter the opposite deep dermis at the same depth, exiting the skin surface 3–5mm from the wound edge, at a point directly across from the entry point. The bite should be symmetrical: equal depth and equal distance from the edge on both sides. Asymmetrical bites cause wound edge eversion on one side and inversion on the other.

Tie using instrument ties: two wraps for the initial throw (surgeon's knot, which resists slipping while you set the tension), then alternating single throws in opposing directions for a total of 4–5 throws. The knot should approximate the wound edges so they just touch, without blanching. Blanching indicates excessive tension and will result in ischemia, necrosis, and a wider scar.

Place sutures 3–5mm apart. The wound edges should evert slightly when closed — this is desirable. Everted edges flatten as the wound matures. Inverted edges heal with a depressed scar.

Cut the suture tails to 5mm length.

Aftercare

Apply a thin layer of petroleum-based ointment and a non-adherent dressing. Instruct the patient to keep the wound clean and dry for 24 hours, after which they may gently clean with soap and water. Face sutures are removed in 5 days. Trunk and extremity sutures in 7–10 days. Sutures over joints or areas of high tension may remain 10–14 days.

Open Appendectomy

Indication

Right lower quadrant pain with tenderness at McBurney's point (one-third the distance from the anterior superior iliac spine to the umbilicus), rebound tenderness, and elevated white blood cell count. CT scan confirms the diagnosis with >95% sensitivity.

Incision

Make a 3–5cm incision over McBurney's point, oriented obliquely along the natural skin crease (Langer's lines). Incise the skin and subcutaneous fat to the external oblique aponeurosis. Open the aponeurosis in line with its fibers using Metzenbaum scissors. Bluntly split the internal oblique and transversus abdominis muscles by separating the fibers with two Kelly clamps inserted into the muscle and opened parallel to the fibers. This muscle-splitting approach (McBurney-McArthur) preserves nerve supply to the muscles and reduces postoperative wall weakness compared to cutting across the fibers.

Open the peritoneum between two hemostats, taking care not to injure underlying bowel. Culture any free fluid.

Identification and mobilization

Identify the cecum by its taenia coli — the three longitudinal muscle bands on the large intestine. Follow any taenia distally and it will converge at the base of the appendix. Deliver the appendix into the wound. If the appendix is retrocecal (behind the cecum, occurring in approximately 30% of patients), mobilize the cecum by dividing its lateral peritoneal attachments.

Mesoappendix division

Identify the mesoappendix, which contains the appendiceal artery. Clamp, divide, and ligate the mesoappendix with 3-0 Vicryl suture in sequential bites from the tip toward the base. Ensure hemostasis at each step.

Appendix removal

Crush the base of the appendix with a Kelly clamp. Move the clamp distally 5mm and reapply. Tie a 0 Vicryl suture in the crush groove at the base. Place a second tie 5mm distal to the first. Divide the appendix between the two ties with a scalpel. Cauterize the mucosal stump with electrocautery to destroy any residual mucosal cells that could form a mucocele.

Some surgeons place a purse-string suture in the cecum and invert the appendiceal stump. Evidence for whether this reduces complication rates compared to simple ligation is equivocal.

Closure

Irrigate the peritoneal cavity with warm saline. Close the peritoneum with a running 3-0 Vicryl suture. The muscle layers do not require suturing if they were split along their fibers — they will re-approximate naturally. Close the external oblique aponeurosis with interrupted 0 Vicryl. Close the skin with 4-0 Monocryl subcuticular running suture or staples.

Apply a sterile dressing. Advance diet as tolerated postoperatively. Discharge in 24–48 hours if uncomplicated.

Common Mistakes

• Placing sutures too tight. The tissue should approximate, not strangulate. If the skin blanches, remove the suture and replace it with less tension.
• Not following the curve of the needle. A curved needle is designed to rotate through tissue in an arc. Driving it straight creates a larger, more traumatic track and bends the needle.
• Inadequate irrigation before wound closure. Closing a contaminated wound over debris produces an abscess. The solution to pollution is dilution.
• Not verifying instrument and sponge counts before and after closure. A retained surgical sponge is one of the most preventable and most consequential errors in surgery.