Epidemiology

Open wounds are frequent reasons for emergency department (ED) visits. The true incidence of foreign bodies (FBs) in wounds is unknown, but with more than 5 million estimated lacerations repaired in EDs in 2007,¹ wound FBs surely occur in such a significant number that all emergency physicians (EPs) will encounter them. Wound FBs are frequently missed on initial evaluation. Seventy-five of 200 FBs encountered in a hand clinic were missed by the initial physician.² Furthermore, missed FBs pose high medicolegal risk for EPs, with one report listing it to be among the top three causes of litigation after wound care.³

Most wound FBs are wood, glass, or metal. The upper extremity is the most common location (58%), followed by the lower extremity (36%). The head and neck (4%) and the trunk (1%) are far less common. Most cases will be seen on the day of injury (75%), but some (8.7%) will initially be evaluated weeks, months, or years later.⁴

Pathophysiology

A retained FB can lay harmlessly dormant for a long period and then can react with surrounding tissue. When a tissue reaction occurs, several sequelae are possible. An infection may occur. The patient’s body may dissolve, extrude, or encapsulate the FB and form a granuloma, and subsequent rupture of the granuloma from minor trauma can cause delayed infection. The extent of tissue reaction depends primarily on the chemical composition of the material. Inert material causes less tissue inflammation, whereas reactive material can cause intense tissue reactions (Box 187.1) and rarely even allergic reactions. Even when an FB does not cause a tissue reaction, it can have other effects. The FB may cause local compression on neighboring structures such as nerves, tendons, joints, or vessels, thereby causing pain or structural damage. Local migration or, more rarely, distant embolization can also occur.

The most threatening FBs are reactive. Wood is especially toxic to soft tissue and virtually always requires removal. FBs causing infection and pain and FBs that are near vital structures such as nerves, tendons, vessels, and joints are also potentially dangerous. Hand FBs tend to migrate locally but rarely embolize, whereas proximal forearm FBs are more likely to embolize.

Presenting Signs and Symptoms

The classic example of a wound FB is a patient who sees or knows that foreign material is present in a wound, such as a splinter, glass in the sole of the foot that the patient cannot remove, or an obviously soiled wound. Alternatively, it is also common for a patient to have a wound and not to know that foreign material is present. The chief complaint of such patients is simply that they have a wound. Certain mechanisms are highly suggestive of wound FBs (Box 187.2).^5–8 Some unique wound FBs include shrapnel, fishhooks, bullets and BBs, cactus spines, and marine material (Table 187.1). Some patients may exhibit sequelae of a retained FB from the near or distant past, such as a mass, persistent pain, infection, functional impairment as a result of nerve or tendon injury, arthritis, vascular injury, or embolization.

Table 187.1 Treatment—Special Circumstances

Neither the presence nor the absence of FB sensation on the part of the patient can confidently rule in or exclude an FB. In a series of 164 wounds caused by glass, 41% that contained glass caused an FB sensation, with a positive predictive value of 31% and a negative predictive value of 89%.⁵

The most important aspect of the physical examination is wound exploration. The wound should be explored in a bloodless field, which may require tourniquets or lidocaine with epinephrine infiltration if direct pressure is insufficient. Adequate anesthesia is crucial. The wound should be visualized completely and with range of motion of the involved digit. The wound can be probed with an instrument. Sometimes an FB is detected only by the grating sound of a metal probe against it. Probing the wound with the examiner’s finger exposes the examiner to puncture wounds and should not be done. The wound can be palpated through the skin with two hands, one stationary as a “stabilizer” and the other mobile as a “mover.” Puncture wounds should be palpated for the exquisite tenderness that may be elicited in the presence of an FB. The function of nearby nerves and tendons should also be evaluated.

Differential Diagnosis and Medical Decision Making

No wound is too small or superficial to harbor an FB, and thus the possibility of an FB must be considered for all wounds. Most wound FBs are initially diagnosed by physical examination (78%), but many are diagnosed primarily by imaging studies (22%).⁴ Exploration alone is insufficient to rule out an FB,^5,9,10 even when the entire wound is thought to be visualized. Therefore, imaging should be used liberally. Selection of the proper imaging modalities requires knowledge of the radiographic properties of the material (Box 187.3 and Figs. 187.1 through 187.3). Even when a suspected FB is not radiopaque, plain film radiographs with an underpenetrated soft tissue technique could be considered because other useful soft tissue or bony findings and reactions may be present. Furthermore, failure to order radiographs has been associated with unsuccessful legal defense in cases of retained FBs.¹¹ Ultrasound scanning is particularly useful for nonradiopaque FBs (Fig. 187.4).⁷ Low-power portable fluoroscopy, when available, is useful to aid in removal of radiopaque FBs. Computed tomography and magnetic resonance imaging are rarely indicated. However, computed tomography may be useful for ocular or periorbital FBs (Table 187.2).^12,13

Fig. 187.1 This patient had a laceration over the olecranon after a motor vehicle collision. A radiograph reveals a foreign body (A). A piece of glass was removed (B).

Fig. 187.2 This patient sustained multiple superficial wounds to the sole of the foot while running barefoot through gravel. A radiograph performed after all gross material was removed revealed two residual foreign bodies (arrows). The bits of gravel were removed.

Fig. 187.3 This patient stepped on broken glass (A). The radiograph, when magnified and scrutinized, showed a possible foreign body (arrow) in the proximity of the wound (B). The wound was explored and a glass foreign body was removed (C). This is an example of the limitations of radiographs for detection of foreign bodies, even those that are radiopaque, in certain locations such as the sole of the foot because of the thickened tissue and multiple bony structures that may obscure the foreign body. This is why wound exploration is also important.

Fig. 187.4 Ultrasound scan showing a wood foreign body with characteristic acoustic shadowing deep to the foreign body.

Table 187.2 Features of Available Imaging Techniques