Surgical Complications: Prevention & Management

Effective hemostasis during Mohs surgery and excisional procedures relies on a layered approach combining mechanical, thermal, and chemical methods. Mechanical hemostasis: direct pressure is the first intervention for any bleeding. Apply firm, focal pressure with gauze for a minimum of 15–20 minutes by the clock (not estimated). Most small-vessel bleeding stops with pressure alone. Electrosurgery: electrocautery (monoterminal) and electrocoagulation (biterminal) are the workhorses of intraoperative hemostasis. Use the lowest effective power setting. Grasp the bleeding vessel with forceps and apply current to the forceps (indirect technique) for precise vessel sealing. Avoid wide-field fulguration near nerve structures. Chemical hemostasis: topical hemostatic agents supplement mechanical and thermal methods. Ligation: for named vessels (angular artery, superficial temporal artery), direct suture ligation with absorbable suture provides definitive hemostasis.

Hematoma is the most common acute complication after Mohs surgery, occurring in 1–4% of cases. The risk is significantly elevated in patients on anticoagulant or antiplatelet therapy. Clinical presentation: progressive swelling, pain, and ecchymosis developing within the first 24–48 hours. Large hematomas cause tense, fluctuant swelling with violaceous discoloration. Expanding hematomas require urgent evaluation. Management algorithm: • Small, stable hematoma (non-expanding): observation, ice application, pressure dressing. Most small hematomas resorb spontaneously over 1–2 weeks. • Large or expanding hematoma: requires evacuation. Open a portion of the wound (remove select sutures), evacuate the clot with irrigation, identify and cauterize the bleeding source, re-close, and apply a pressure dressing. • Hematoma under a flap: urgent evacuation is critical. Pressure from the hematoma compromises flap perfusion and can cause flap necrosis. Open, evacuate, achieve hemostasis, and re-secure the flap. • Hematoma under a graft: aspirate or evacuate through a fenestration; re-apply bolster. Hematoma is the most common cause of graft failure.

SSI in dermatologic surgery is classified by timing and depth: Superficial incisional SSI: involves skin and subcutaneous tissue within 30 days of surgery. Presents with erythema, warmth, swelling, purulent drainage, and pain. Deep incisional SSI: involves fascia or muscle layers. Uncommon in typical Mohs procedures but possible in deep excisions. Risk factors for SSI after dermatologic surgery:

Wound dehiscence is partial or complete separation of the wound edges after closure. It is the second most common complication after hemorrhage. Causes of dehiscence: • Excessive wound tension (most common cause). Inadequate undermining, insufficient deep sutures, or closure under tension • Infection. Purulent material undermines wound adhesion • Hematoma/seroma. Fluid collection separates wound edges • Premature suture removal. Before adequate tensile strength develops • Patient non-compliance. Premature activity, trauma to wound Management: small dehiscences (< 50% of wound length) can often heal by secondary intention with excellent cosmetic results, particularly on concave surfaces. Large dehiscences may require re-closure (delayed primary closure) or revision after healing is complete. For dehiscence caused by infection: open the wound completely, irrigate, initiate antibiotics, and allow healing by secondary intention. Do NOT re-close an infected wound.

Tissue necrosis after flap surgery results from inadequate blood supply to the transferred tissue. It is more common in random pattern flaps where the length-to-width ratio is excessive or the pedicle vasculature is compromised. Risk factors for flap necrosis: • Excessive flap length-to-width ratio (>3:1 for random pattern flaps) • Smoking. Nicotine causes vasoconstriction and reduces tissue oxygenation • Excessive tension at the flap tip • Hematoma under the flap • Prior radiation to the surgical site • Peripheral vascular disease / diabetes Early signs: dusky discoloration (blue/purple) at the flap tip, cool temperature, delayed capillary refill, and progressive darkening. These signs typically appear within 24–72 hours. Management: if caught early, relieve all tension (remove some sutures), evacuate any hematoma, and optimize blood flow (warmth, stop vasoconstrictors). If necrosis is established, allow demarcation over 1–2 weeks, then debride necrotic tissue and allow healing by secondary intention or perform revision.

The facial nerve (CN VII) is the most commonly injured motor nerve during cutaneous surgery. The temporal and marginal mandibular branches are at greatest risk because of their superficial course. Danger zones for motor nerve injury:

Sensory nerve injury is more common than motor nerve injury after dermatologic surgery but causes less functional morbidity. Transient numbness or paresthesia is expected after any procedure involving undermining. Commonly affected sensory nerves: • Supraorbital / supratrochlear (CN V1): forehead and anterior scalp numbness after forehead/glabella surgery • Infraorbital (CN V2): cheek, upper lip, and lateral nose numbness after midface surgery • Mental nerve (CN V3): lower lip and chin numbness after mandibular area surgery • Great auricular nerve: ear and periauricular numbness after neck/ear surgery Prognosis: most sensory nerve injuries recover within 3–12 months as nerve regeneration occurs at approximately 1mm per day. Complete division of a major sensory nerve trunk causes permanent anesthesia in its distribution.

Distortion of free margins (eyelid, nasal alar rim, lip) is a functional and cosmetic complication caused by excessive tension directed toward the free margin during wound closure. Prevention strategies: • Visualize tension vectors before incision. Ensure the primary closing force does not pull directly on a free margin • Choose flap designs that redirect tension AWAY from the nearest free margin • Wide undermining to distribute tension broadly rather than concentrating it at the margin • Anchor deep sutures to periosteum or fixed tissues to redirect tension • Consider staged repairs or grafts for defects where no flap orientation can avoid margin distortion Management: mild distortion often improves as wound contraction and remodeling occur over 3–6 months. Significant distortion (functional impairment) may require scar revision, Z-plasty, or secondary reconstruction after wound maturation.