Chapter 103. Subungual Foreign Body Removal

Subungual foreign bodies are often difficult to treat. Foreign bodies such as wood or metal splinters, pencil lead, thorns, spines, or hair may become lodged beneath the fingernail.1–3 Tradesmen such as carpenters, landscapers, auto mechanics, and individuals who work without hand protection with materials that produce small splinters are at risk for this type of injury. Subungual foreign bodies may also present less commonly under the toenails.

Patients generally present for medical intervention with pain after unsuccessfully attempting to remove the foreign body. Prior removal attempts often result in breakage of the foreign body or pushing it further beneath the nail; both of which complicate the next extraction attempt. Left untreated, retained subungual foreign bodies often become infected or cause tissue reactions and granuloma formation. These injuries may be treated rapidly with complete removal of the foreign body and without causing additional patient discomfort.

The distal fingertip and nail apparatus are complex structures (Figure 103-1). The perionychium is composed of the nail bed and the surrounding soft tissue. The hyponychium is the junction of the nail bed at the sterile matrix and the fingertip skin beneath the distal margin of the nail plate. The eponychium is the distal portion of the nail fold where it attaches to the proximal surface of the nail plate. The lunule is the white arc seen on the proximal portion of the nail plate. The nail bed consists of the germinal matrix on the proximal ventral floor of the nail fold and the sterile matrix that extends from the lunule to the hyponychium. The germinal matrix is primarily responsible for the growth of the nail. The subungual space is the area immediately beneath the nail plate.

Foreign bodies may enter the subungual space at the distal fingertip beneath the nail, or may penetrate the nail plate directly (Figure 103-2). In either event, separation of the nail from the nail bed results in severe pain. Patients frequently attempt to remove the foreign body immediately because of this intense pain. An infection or foreign body reaction will often ensue if the foreign body is not removed in its entirety.

Subungual foreign bodies should be removed to prevent the complications of infection, foreign body reaction, and possible nail deformity. Deeply embedded foreign bodies, splintered foreign bodies, those that traverse the nail plate, or contaminated foreign bodies may require the removal of the nail plate to extract the foreign body. Refer to Chapter 104 regarding the details of removing the nail plate. Consult a Hand Surgeon if the foreign body cannot be removed, if the site is infected, if the foreign body is “chronic” and an osteomyelitis is present on radiographs, or if significant injury to the digit is present.

There are no absolute contraindications to the removal of a subungual foreign body.

General Supplies

• Povidone iodine or chlorhexidine solution
• Alcohol swabs
• Sterile saline solution
• Topical antibiotic ointment
• Nonadherent dressing (e.g., petrolatum gauze)
• 4 × 4 gauze squares
• Adhesive tape

Digital/Metacarpal Block

• 3 mL syringe
• 25 or 27 gauge needle, 1 in. long
• 3 to 5 mL local anesthetic solution without epinephrine

Scrape Technique

• Splinter forceps
• #11 or #15 scalpel blade on a handle

Wedge Technique

• Splinter forceps
• Tissue scissors or nail clippers

Needle Technique

• Needles, 19 and 25 or 27 gauges
• Splinter forceps
• Hemostat

Explain the risks and benefits of the procedure to the patient and/or their representative. Obtain an informed consent for the procedure. Ascertain the patient's tetanus immune status and administer the appropriate tetanus prophylaxis. The Emergency Physician should attempt to gain the patient's cooperation. Place the patient sitting or in a semi-recumbent position with their hand on a bedside procedure table. Clean any dirt and debris from the affected finger. Apply povidone iodine or chlorhexidine solution and allow it to dry. Any manipulation of the nail bed will result in additional patient discomfort. Determine the need for a digital or metacarpal block depending on the type and extent of the foreign body and the removal technique. Please refer to Chapter 126 for the complete details regarding anesthesia of the finger or toe. Radiographs are not required unless a metallic foreign body cannot be visually located or the clinical suspicion exists for an osteomyelitis or a gas forming finger infection.

Foreign bodies protruding through or from underneath the nail plate may be grasped with a forceps and removed. A scalpel blade or 18 gauge needle may be used to entrap a small protruding tip of the foreign body against the nail plate and draw it out. Do not attempt to remove the foreign body through a puncture wound or small incision. Enlarging the access site allows for easier removal, not breaking or fragmenting the foreign body, and complete removal. Superficially located subungual foreign bodies may be removed by one of the following techniques.

Scrape Technique

This technique has been described anecdotally.4,5 It appears promising as it does not require the administration of a digital block and causes less trauma to the nail and the nail bed compared to other techniques. This technique works well for subungual foreign bodies that either traverse the nail plate or are lodged beneath the distal or middle portion of the nail.

Support the patient's hand on a procedure table. Sit on a chair facing the patient. Place a #11 or #15 scalpel blade on the nail plate and directly over the foreign body (Figure 103-3A). Hold the blade perpendicular to the surface of the nail plate. Draw the scalpel blade from proximal to distal using short strokes and gentle pressure over the foreign body (Figure 103-3A). A small shaving of the nail plate is removed with each stroke of the scalpel blade. The finger may be soaked in lukewarm water for 15 to 20 minutes to soften the nail plate if it is thick and difficult to shave. Continue to remove successive slivers of the nail plate to eventually create a U-shaped defect and expose the foreign body (Figure 103-3B). Grasp the foreign body with a splinter forceps and remove it once a significant portion protrudes. The defect created in the nail plate will move distally and eventually be replaced as the nail plate continues to grow.

Wedge Technique

The wedge technique works well for subungual foreign bodies lodged beneath the distal portion of the nail plate.1,6 Patients will require a digital or metacarpal block prior to attempting this technique since it involves manipulation of the nail bed.

Sit on a chair facing the patient. Cut a triangular wedge from the distal portion of the nail plate overlying the foreign body with a small pair of tissue scissors or nail clippers (Figure 103-4A). Prevent iatrogenic injury to the nail bed by ensuring that the tip of the scissors under the nail plate is aimed upward and against the nail plate. Remove the wedge of nail. This will provide enough exposure to grasp and remove the foreign body with splinter forceps (Figure 103-4B).

Needle Techniques

The needle technique works well for subungual foreign bodies located beneath the distal portion of the nail plate.1 Patients will require a digital or metacarpal block prior to attempting this technique. Insertion of a needle into the nail bed is extremely painful. The major drawback of this technique is the potential for leaving fragments of the foreign body beneath the nail plate.

Sit in a chair facing the patient. Introduce a 19-gauge needle beneath the nail plate and along the track of the foreign body (Figure 103-5A).7 Use the tip of the needle to touch the foreign body. Lower the hub of the needle to raise its tip and trap the foreign body between it and the nail plate. Withdraw the needle while dragging the foreign body out along the nail plate. Alternatively, tease out and move the foreign body distally until it can be grasped with a splinter forceps.

Two alternate techniques have also been described for the needle extraction of a subungual foreign body.7,8 The first is a modification of the needle technique.7 Place a hook in the distal end of a 25 or 27 gauge needle with a hemostat or needle driver (Figure 103-5B). Pass the bent needle along the foreign body tract. Grasp the foreign body with the tip of the bent needle. Withdraw the needle to move the foreign body distally so that it may be grasped with a splinter forceps. A third technique involves the excision of a small portion of the nail plate overlying the foreign body with an 18 gauge needle.8 This is similar to the shave technique with the exception of an 18 gauge needle being used instead of a scalpel blade.

The subungual area should be inspected for any remaining fragments of the foreign body that may have broken off in the nail bed. Any remaining fragments of the foreign body must be removed. Refer the patient to a Hand Surgeon if the foreign body fragments cannot be removed.

In most cases, local wound care and the application of a topical antibiotic are all that is required. Irrigate the foreign body tract and excision site with sterile saline. Apply topical antibiotic ointment to the area. Apply a nonadherent dressing over the nail. Follow-up with a Hand Surgeon and systemic antibiotics may be necessary in severe cases, such as the presence of a nail deformity or chronic foreign bodies with an infection. Postprocedural pain can be managed with acetaminophen or nonsteroidal anti-inflammatory drugs. The use of prophylactic antibiotics is not recommended unless the foreign body was contaminated or had deeply penetrated into the soft tissue of the digit. Instruct the patient to return immediately to the Emergency Department if they develop any signs of an infection (i.e., purulent drainage, increased tenderness, redness or swelling of the digit, or fever).

There are a few potential complications from subungual foreign body removal. Damage to the nail bed can result in a residual nail deformity. Failure to completely remove a subungual foreign body may result in a nail deformity, an infection, or a foreign body reaction with granuloma formation. An infection can result from a contaminated foreign body, flora on the nail plate or skin driven into the soft tissues by the foreign body, or if aseptic technique is not followed.

Patients with subungual foreign bodies often present in severe pain after prior unsuccessful attempts at removal or after complications develop. Though sometimes challenging, it is important that the Emergency Physician completely remove the foreign material in the subungual space to prevent further complications. Providing adequate anesthesia and using the appropriate instruments and techniques allows the successful removal of most subungual foreign bodies in the Emergency Department.