Chapter 39: Wound Evaluation

Evaluation of the patient with a traumatic wound begins with overall patient assessment.^1,2 Less obvious but more serious life-threatening injuries need care before directing attention to wound management. Determine the patient's past medical history and circumstances surrounding the injury.^1,2 Remove rings or other circumferential jewelry as soon as possible so they do not act as constricting bands when swelling progresses. Remove clothing over the injured area to reduce the potential for contamination.

External bleeding can usually be controlled by direct pressure over the bleeding site. When possible, replace skin flaps to their original position before applying pressure in order to avoid exacerbating vascular compromise. Tourniquet application may be necessary to stop life-threatening exsanguination or when needed for a short period to create a "bloodless" field for wound inspection.^3,4,5 Amputated fingers or extremities should be wrapped with a moist, sterile, protective dressing, placed in a waterproof bag, and then placed in a container of ice water for preservation and consideration for future reattachment. Before wound exploration, cleansing, and repair, most patients will need some form of anesthesia.⁶ Systemic analgesia or procedural sedation may be required (see chapter 35, Acute Pain Management, and chapter 37, Procedural Sedation).

Proper wound management begins with a pertinent patient history (Table 39-1).^1,2 A variety of patient factors have adverse effects on wound healing and increase the rate of wound infection—extremes of age, diabetes mellitus, chronic renal failure, obesity, malnutrition, the use of immunosuppressive medications, the presence of connective tissue disorders, and protein and vitamin C deficiencies.¹ Predictive factors for infection are the wound characteristics of location, age, depth, configuration, and contamination.^7,8

Ascertain the tendency of patients to form hypertrophic scars or keloids by both history and examination, as past experience may predict poor scar formation. Black and Asian patients are more prone to keloid formation than whites. Hypertrophic scars are due to tissue tension during wound healing, and these scars stay within the original wound boundaries and tend to undergo partial spontaneous regression within 1 to 2 years. Keloids are genetically linked variations in wound healing, resulting in the production of excess collagen beyond the original wound boundaries (Figure 39-1). Once they form, keloids rarely decrease in size.

Obtain a detailed history of allergies or prior adverse reactions to anesthetic agents or antibiotics. Review any prior allergies to latex.⁹ Determine the status of prior tetanus immunization and the need for further tetanus vaccination (see chapter 156, Tetanus).

Review the mechanism of injury to identify the presence of potential wound contaminants and foreign bodies. Bite wounds are at high risk for infection and are generally managed differently than other lacerations (see chapter 46, Puncture Wounds and Bites). Foreign bodies are common in puncture wounds, wounds associated with broken glass, and motor vehicle collisions.^10,11,12,13 Ask about the presence of a foreign body sensation. In adults, those reporting a foreign body sensation are more likely to have a retained foreign body than those who do not (positive likelihood ratio = 2.49 and negative likelihood ratio = 0.69).¹⁴ This question has little utility in children.¹⁵

Both foreign body retention and visible contamination increase the risk of infection.^7,8 Organic and inorganic components of soil can cause infection even from very small doses of bacterial inoculum. Clay is the major inorganic soil component responsible for infection. Conversely, sand grains and black dirt from roadways are relatively inert.

The likelihood of wound infection varies according to the forces applied at the time of injury.^7,8 The most common mechanism for traumatic wounds is blunt force. The skin is crushed against underlying bone and tears or splits from the subsequent tension. Sharp objects produce shear forces that cut skin cleanly. Crush injuries produce more tissue devitalization and are more susceptible to infection than wounds from shear forces.

Low-energy impact injuries may not result in lacerations, but instead may disrupt vessels, leading to ecchymosis or hematoma formation. Some hematomas spontaneously resorb. Those that become encapsulated may eventually require aspiration or incision and drainage.

Determine the time that the injury occurred. Although the growth of the bacterial inoculum is directly related to the time interval from injury to laceration repair,^1,7 there is no clearly defined relationship of time to closure to clinical infection^16,17,18 (Table 39-2). Therefore, time from injury until presentation is only one element to be considered, in addition to the wound etiology, location, degree of contamination, host risk factors, and the importance of cosmetic appearance, before determining whether or not to perform primary wound closure. Wounds that are not closed primarily because of a high risk of infection should be considered for delayed primary closure after 4 days. The clinical consensus of wound care experts is that after 4 days of open wound management, the risk of infection after closure substantially decreases, although this approach has not been subjected to randomized controlled trials.¹⁹

Determine whether the wound was the result of an intentional, unintentional, or workplace event. Most states have regulations that require the reporting of intentional injuries, and patients with self-inflicted injuries may need psychiatric evaluation. Occupational injuries may require alternative follow-up arrangements.

The anatomic location of the injury helps predict the clinical outcome, both in terms of infection risk and cosmetic result^7,8,15,20 (Table 39-3). The risk of infection is determined largely by the interplay between baseline bacterial colonization and vascular blood supply. With respect to bacterial colonization, the density of the bacterial population is low on the upper arms, legs, and torso. Conversely, moist areas of the body, such as the axilla, perineum, toe webs, and intertriginous areas, harbor millions of bacteria per square centimeter, including anaerobes. Obviously, any wounds with human or animal fecal contaminants run a high risk of infection, even with therapeutic intervention.

Wounds located on highly vascular areas, such as the face or scalp, are less likely to be infected than wounds located in less vascular areas.^7,8,15,17,20 The increased vascularity of the area more than offsets the high bacterial inoculum found in the scalp, and lacerations of the scalp and face have a very low infection rate regardless of the intensity of cleansing.²¹ While prophylactic oral antibiotics have traditionally been considered as warranted for intra-oral lacerations, there is inconclusive evidence to support their use.²²

Thorough wound examination should be conducted when the patient is calm and cooperative and positioned appropriately, with optimal lighting conditions, and with little or no residual bleeding (Figure 39-2).

Cursory examination under poor lighting or when the depths of the wound are obscured by blood will occasionally result in poor detection of foreign bodies and tendon, nerve, and vascular injuries. If bleeding is a problem, epinephrine-containing anesthetic solutions may be helpful, when not contraindicated. Tourniquets may be used to obtain a bloodless field, but they should not be used for more than 30 minutes.^3,4,5 Lacerations over joints may have penetrated the joint capsule, and sometimes it is necessary to inject the joint to ensure that there is no communication between the joint space and the laceration. Evaluate the wound in neutral position and also in the position present during injury. Chain-saw knee wounds, for example, are often sustained with the knee in flexed position. Repositioning the joint or extremity in the position assumed during injury can better reconstruct the mechanism of injury and identify injured structures. Lacerations over the metacarpophalangeal joints are suspicious for having occurred during a fight (clenched fist injury) and should be treated as though they are human bites.

Although most lacerations will not require any diagnostic testing, on occasion, wound imaging for detection of foreign bodies may be necessary (see chapter 45, Soft Tissue Foreign Bodies). Most foreign bodies commonly found in wounds are much denser than the surrounding tissue and are readily apparent on plain radiographs. Metal, bone, teeth, pencil graphite, certain plastics, glass, gravel, sand, some fish bones, some painted wood, and most aluminum are visible on plain radiographs.

CT and MRI are useful for identifying and locating objects that have densities similar to soft tissue. US may also be useful, particularly for wooden foreign bodies, although the sensitivity of US is inadequate to reliably exclude small (<2.5 mm) wood fragments.

Patients should be carefully educated regarding the expected cosmetic outcome. They should be informed that there will be some scarring and, if predisposed, possible keloid formation.¹ Some indication of the maximal width of the scar can be predicted based on wound location, whether the laceration is aligned parallel or perpendicular with lines of minimal tension, and how gaping the wound is while at rest (static tension) or when put through a range of motion (dynamic tension).^20,23 Lacerations over joints (which have more dynamic tension) will have wider scars than similar lacerations subject to less tension. Wounds that deviate from the lines of skin tension will also be prone to greater scar formation after suturing than wounds that are more closely aligned with skin tension.²³ The most important determinant of cosmetic outcome under control of the treating physician is meticulous wound repair with approximation of viable wound edges under little tension. Patients should be clearly educated that all lacerations result in some scarring.