Chapter 106. Subcutaneous Abscess Incision and Drainage

Subcutaneous abscesses are commonly seen in the Emergency Department. Approximately 1% to 2.5% of patients present with this chief complaint.1–3 Abscesses occur in numerous anatomical areas with varied etiology and bacteriology. An abscess is a tender and fluctuant mass located in the dermal or subdermal tissue. It usually demonstrates the classic inflammatory responses of rubor, tumor, dolor, and calor. Although the abscess is usually tender, the surrounding and underlying tissue should not be tender.4,5 There is usually minimal surrounding erythema in a mature abscess.

Incision and drainage is the definitive treatment of a soft tissue abscess.6 This procedure results in significant improvement in symptoms and a rapid resolution of the infection in uncomplicated cases.7 However, premature incision before localization of pus will not be curative and may be deleterious. In cases of immature abscesses or cellulitis, oral antibiotics and warm compresses may be of value in helping the infection to coalesce. These methods are not a substitute for incision and drainage and should not be continued for more than 24 to 36 hours without a reassessment of the patient. With the emergence of methicillin-resistant Staphylococcus aureus (MRSA), the role for ancillary antibiotic use has come into question.

Pathogenesis

An abscess is a localized collection of pus caused by suppuration buried in a tissue, organ, or confined space.8 Intact skin is very resistant to bacterial invasion. Localized pyogenic infections are usually initiated by a breakdown in the normal epithelial defense mechanisms in the normal host. Plugging of the ducts of a superficial exocrine gland, such as apocrine and sebaceous glands or a congenital cyst or sinus, may initiate the process. Occlusion prevents desquamation and provides a moist environment for organisms to proliferate. The combination of a high concentration of organisms, the presence of nutrients, and sufficient damage to the corneal skin layer to allow organisms to penetrate the skin defenses results in abscess formation.1,9

Subcutaneous abscesses typically begin as a cellulitis with organisms that cause necrosis, liquefaction, and accumulation of leukocytes and debris. Early stages appear as an area of hyperemia and tender inflammation that later becomes fluctuant as an exudate of leukocytes, necrotic material, and cellular debris accumulates. This is followed by loculation and walling off of the pus. This progresses and the area of liquefaction increases until it “points” and eventually ruptures through the area of least resistance.5

The body area involved depends upon host factors such as drug use, employment-related exposures, or minor trauma.9,10 Areas with a compromised blood supply are more prone to infection as normal host cell-mediated immunity is not as available.9 The frequency of abscess occurrence in different body areas includes the buttocks and perirectal area in 25% of cases, the head and neck in 20%, the extremities in 18%, the axilla in 16%, and the inguinal area in 15%.1

Bacteriology

The majority of abscesses are polymicrobial with the isolated organisms usually representing the normal resident flora associated with the body area on which the abscess is found.1,11 Nonresident bacteria are found in abscesses that occur as a result of direct inoculation of extraneous organisms such as those following human bite wounds, intravenous drug use, or bacterial seeding of embedded foreign bodies.12 In normal hosts, aerobic Staphylococcus and group A Streptococcus are the most common organisms isolated from abscesses of the head, neck, extremities, and trunk.11,13 Anaerobes are found in all areas of the body but predominate in abscesses of the buttocks and perirectal regions.11,13

Staphylococcus aureus occurs in 24% to 60% of abscesses and in pure cultures is the only organism in 21% to 72% of cases.1,13–16 Community-acquired MRSA (CA-MRSA) is presently considered to be the most common identifiable pathogen causing abscess at major centers.17 CA-MRSA is defined as infection with MRSA acquired in the community lacking the traditional risk factors of hospital-acquired MRSA including a recent stay in a long-term care facility or in a day care setting, recent healthcare contacts or surgery, an indwelling device, dialysis, immunosuppression, chronic illness, or recent antibiotic use.18,19 Many cohorts of patients who are at a higher risk of acquiring MRSA infections include those with recent household or daycare contacts, children, men who have sex with men, those in the military, incarcerated patients, athletes (especially those in contact sports or who share equipment), Native Americans, Pacific Islanders, patients with previous MRSA infections, and intravenous drug users.18–21 While it is important to consider MRSA in patients with aforementioned risk factors it is essential not to exclude MRSA in the absence of them.17 Patients presenting with a complaint of a “spider bite” should be investigated for MRSA.18,19,22 In a recent observational study of urban patients, MRSA was isolated from abscesses in 51% of patients.23 An American study of 11 academic centers found MRSA incidence rates as high as 74% in patients presenting with abscesses.17 As much as 77% of MRSA-related illness, especially presenting in the Emergency Department, are skin and soft tissue infections (SSTI).24

CA-MRSA carries the mecA gene, which is thought to impart the antimicrobial resistance. This is carried on the Staphylococcal Cassette Chromosome Type-IV, which is distinct from other forms of MRSA.18,19 CA-MRSA also produces an exotoxin called Panton-Valentine Leukocidin (PVL) that predisposes patients to cutaneous infections.18,19 PVL has been identified in up to 98% of CA-MRSA cases.17

Up to 17% of abscesses are sterile.1,7,13 Nearly 40% of these are secondary to intravenous drug use and most likely result from injection of necrotizing chemical irritants.3 Viruses (e.g., herpes), autoimmune mechanisms, or systemic illnesses including metastatic tumors, benign tumors, and granulomatous disease may also cause sterile abscesses.4,25 These atypical etiologies may present with the absence of local inflammatory signs and symptoms and only with an exacerbation of the underlying disease process.

Specific Clinical Entities

Furuncles, or boils, are acute circumscribed abscesses of the skin and subcutaneous tissue that most commonly occur on the face, neck, buttocks, thigh, perineum, breast, or axilla. Carbuncles are aggregates of interconnected furuncles that frequently occur on the back of the neck where the thick skin causes lateral extension of the infection rather than pointing toward the skin surface. These occur with a higher frequency in diabetics. They can be large and cause systemic signs, symptoms, and complications. Carbuncles often require surgical consultation and treatment in the Operating Room.

Hidradenitis suppurativa is a chronic relapsing inflammatory disease process affecting the apocrine glands primarily in the axilla, the inguinal region, or both.26 Initially, this process will appear like a typical abscess and is only identifiable in its chronic scarring phase when there are multiple lesions with tender areas of induration and inflammation in various stages of healing. The chronic process leads to draining fistulous tracts that require ongoing surgical management. Emergency Department management involves the usual incision and drainage procedure of any area of fluctuance. Patients should be informed that the intervention is not curative and that the problem is chronic. Arrange a referral to a General Surgeon, Dermatologist, or Plastic Surgeon for long-term follow-up.

Up to 80% of breast abscesses occur in nonlactating women.4 Peripheral and superficial lesions are similar to abscesses elsewhere on the body and respond to conservative incision and drainage with an incision that radiates out (centripetally) from the nipple.27 Deeper and periareolar abscesses are often complex and require surgical referral and general anesthesia to properly treat. Postpartum mastitis is common and precipitated by milk stasis and bacterial invasion through a cracked nipple. The offending organism is commonly Staphylococcus aureus or Streptococcus species. Treatment includes the application of heat, oral antibiotics, and continued breast emptying with a breast pump or feeding of the baby. The mastitis may evolve into an abscess and is often associated with systemic symptoms. Appropriate antibiotic therapy and follow-up in 24 to 48 hours is required.

Sebaceous cysts are a common cause of a subcutaneous abscess. They can persist for long periods as nontender subcutaneous swellings before becoming infected. They appear like most other abscesses. Sebaceous cysts can be identified by a small punctate sinus tract near the center of the fluctuant area. The initial treatment is incision and drainage. The contents are usually thick cheesy material that needs to be manually expressed. A sebaceous cyst has a definite shiny white capsule that must be excised, preferably at the time of incision and drainage or at the first follow-up visit, to prevent recurrence. The area is then treated as any other healing abscess cavity.

The recurrence of an abscess that has been previously drained should suggest the possibility of underlying osteomyelitis, a retained foreign body, or the presence of unusual organisms such as mycobacteria or fungi. Recurrent abscesses should prompt further investigation including an assessment of the patient's immune status.

Special Considerations

The precise risk for endocarditis associated with subcutaneous abscesses is unknown. Up to 5% of patients with abscesses have bacteremia at the time of presentation.4,16 Incision and drainage of cutaneous abscesses can result in transient bacteremia with the organism causing the abscess.7,14,28 More recently, the clinical relevance of this bacteremia has become controversial.16 At this time, only patients considered to be at high risk for endocarditis are recommended to receive antimicrobial prophylaxis before incision and drainage (Table 106-1).29 Bacterial endocarditis prophylaxis should be directed at the most likely pathogen causing the infection. An antistaphylococcal penicillin or a first-generation cephalosporin is an appropriate choice for most soft tissue infections (Table 106-2). Clindamycin is an acceptable alternative for patients allergic to penicillin. Patients with immunodeficiency and localized soft tissue abscesses may be at higher risk for developing septicemia secondary to bacteremia induced by incision and drainage, but it is unclear if they are at higher risk of complications and death.30,31 These patients may benefit from prophylactic antibiotics prior to incision and drainage, but only indirect evidence and no controlled studies are available.32 High-risk patients with known or suspected MRSA infection should receive IV Vancomycin or Clindamycin when undergoing incision and drainage.29

Prior to the treatment of an abscess, a focused history should be taken assessing for trauma, intravenous drug use, history of fever, and past medical history. Specifically inquire about diabetes, renal failure, steroid use or other immune suppression, peripheral vascular disease, and valvular heart disease. It is important to note any of the aforementioned risk factors for CA-MRSA as this may alter management of certain patient populations. Past anesthetic history and the potential for aspiration should be assessed if procedural sedation is to be considered.33 Medications and allergies should be queried. The patient's tetanus status must be confirmed and booster doses provided as required.

A brief physical examination documenting function and intact distal neurovascular status of extremities involved is required. Evidence of pain on passive or active movement of fingers may suggest a deep space infection.4 A high index of suspicion is required, especially in injection drug users (IDU), to identify those seemingly simple cutaneous infections that unpredictably evolve into extensive necrotizing soft tissue infections.34 General assessment of the airway and cardiopulmonary system, vital signs, and mental status is indicated if procedural sedation is to be employed.33

Routine laboratory studies are not indicated in otherwise healthy individuals. In immunocompromised patients, a CBC looking for leukopenia or toxic granulations should be considered. Diabetics should have electrolytes, BUN, creatinine, and glucose assessed. Elevated potassium in diabetics may indicate myonecrosis.35 Consider a urinalysis for myoglobinuria.

Culturing the purulent material from a drained abscess was previously considered to be of little value. Controversy exists today as to the value of culture in abscess management. While many experts suggest that it is of little value because it has no bearing on acute management (curative I & D), others suggest that it is vital to help determine antimicrobial susceptibility and outbreak patterns.22 Cultures should be obtained as they may alter later management in cases with recurrent or refractory infections, those patients who are seriously ill or immunocompromised, patients on an antimicrobial with variable activity, those who have failed surgical treatment, and any patient being admitted to the hospital.22,36 Gram stain and cultures for both aerobic and anaerobic bacteria may be helpful in those patients who are febrile, systemically unwell, immunocompromised, or who present atypically. Consider obtaining radiographs of the affected areas if there is a history of trauma, drug use, or concern regarding deep infection. Foreign bodies and fractures may not be easily identifiable because of the edema and tenderness caused by the infection. Gas or osteolytic lesions on plain radiographs may indicate severe deeper infection, the need for urgent surgical consultation, and prompt antibiotic therapy.37

Ultrasonographic Evaluation

Bedside ultrasound use in the Emergency Department is of great value to the Emergency Physician in evaluating skin and soft tissue infections. This modality can be used to differentiate a cellulitis from an abscess in difficult cases. Ultrasound is portable, inexpensive, comfortable for patients, and provides no radiation exposure. It is fast and easy to gain proficiency for specific applications.38 Ultrasound is indicated for ambiguous physical findings such as widespread cellulitis, localizing an incision site, and for ruling out dangerous masses such as a pseudoaneurysm that masquerade as an abscess.39 Ultrasonography is helpful in identifying small or early abscesses, deep abscesses, abscesses under previous scars, and for localizing adjacent major vessels or nerves.39 Recent studies have found that ultrasound has a sensitivity of 98% and specificity of 88% in detecting an abscess.38 One study of presumed cellulitis in the Emergency Department found that ultrasound changed the case management in 71 of 126 patients (56%), as swelling thought to be due to cellulitis can hide an abscess.40 In the pediatric population, ultrasound is useful in evaluating a cellulitis and determining if an incision and drainage is necessary.41 Finally, ultrasound can be used to guide an aspiration to confirm the presence of an abscess and to obtain material for culture and gram stain.42

Before ultrasonographic examination, it is important that the Emergency Physician has an appreciation of the anatomical structures of the area. The location and sonographic appearance of arteries, veins, nerves, and tendons should be known before the incision and drainage procedure. Generally, a 5 to 7.5 MHz linear array transducer is used. Some find a standoff pad or gel-filled glove to be useful for superficial structures.39 Once the probe has been electronically focused to an ideal depth, scan the area of infection in two orthogonal planes.39,40 Lower frequency transducers are useful for deeper abscesses, while higher frequency probes are more effective for superficial abscesses. It is important to use probe covers as well as proper cleaning and disinfecting supplies in order to avoid cross contamination.

Differentiation between a cellulitis and an abscess on ultrasound is based on several findings. Cellulitis shows diffuse hyperechogenicity and thickening of the skin and subcutaneous fat. The presence of echo-poor strands between hyperechoic fatty lobules in the subcutaneous tissue is known as cobblestoning and is indicative of cellulitis.38,39,42 (Figure 106-1). An abscess has a wider array of presentations on ultrasound. Most frequently, an abscess is a spherical or elliptical shaped anechoic or echo-poor region with sharper echogenic borders.39,43 (Figure 106-2). Within the echo-poor area there may be gas, lobulations, septations, and echogenic debris. There are some cases where the abscess can appear to be isoechoic and even hyperechoic. In these cases, there may be a role for ultrasound-guided aspiration.43 If unsure if an abscess is present on ultrasound, gentle digital palpation or pressure may induce motion of the purulent material within the abscess.43 Posterior acoustic enhancement can be seen in the presence of an abscess.39 This technique can help rule out similarly presenting hematomas, necrotic tumors, vascular lesions, or schwannomas.42 There is an emerging role for Doppler ultrasound in abscess evaluation. The findings of increased vasculature, peripheral blushing and hyperemia, and increased large vessel flow around the abscess are common (Figure 106-3).44

The presence of a fluctuant mass in an area of induration, erythema, and tenderness is clinical evidence that an abscess requires incision and drainage. Antimicrobial treatment without incision and drainage can lead to treatment failures in patients with abscesses.45 Examination alone may not definitively indicate an abscess, especially if it is deep. This can be further confirmed by bedside ultrasound, with or without needle aspiration.4 Obtaining purulent material on aspiration identifies an abscess and is an indication for incision and drainage.4 If no pus is aspirated, oral antibiotics, warm compresses, and follow-up in 24 hours must be arranged for a reassessment.

The only absolute contraindication to the incision and drainage of an abscess in the Emergency Department is the possible association with a mycotic aneurysm.10,35 Commonly, abscesses overlie large vessels including those in the anterior triangle of the neck, the supraclavicular fossa, the deep space of the axilla, the antecubital fossa, the groin, and the popliteal space.46 In these locations, or if the abscess is pulsatile, fine needle aspiration for blood, diagnostic imaging, and/or angiography is indicated prior to incision and drainage.

Relative contraindications to incision and drainage include an inability to achieve adequate anesthesia. An abscess associated with a deep foreign body that requires additional real-time imaging such as a fluoroscopy or ultrasound may require surgical referral.47 Proximity of an abscess to important neurologic, tendinous, or vascular structures may require specialty consultation and magnification in the operating room. Deep space infections or involvement of any joint requires admission for parenteral antibiotic therapy and possible operative debridement. Patients presenting with soft tissue infections exhibiting pain out of proportion to physical examination findings or deep anesthesia of the involved or distal area should raise the possibility of deeper infections such as necrotizing fasciitis or myonecrosis.37 Perirectal and periurethral abscesses are often larger and deeper than they appear and may be complicated by sinus tracts that require exploration under general anesthesia. Manipulation of abscesses in the “danger triangle” of the face (corners of the mouth to glabella) can lead to septic thrombosis of the cavernous sinus. Periorbital or orbital abscesses require ophthalmologic assessment and treatment.

Anesthesia

• 18 and 27 gauge needles, 1½ in. long
• 10 mL syringes
• Povidone iodine or chlorhexidine solution
• Local anesthetic solution with epinephrine
• Local anesthetic solution without epinephrine if abscess is near an end arteriolar system
• Ethyl chloride spray
• Ice pack

Procedure

• #11 and #15 scalpel blades on a handle
• Two hemostats, in two sizes for breaking up loculations and probing the cavity
• Scissors
• Normal saline
• 10 or 20 mL syringe with a 20 or 22 gauge angiocatheter
• Suction source, tubing, and catheter for larger abscesses
• 4 × 4 gauze squares
• Iodoform gauze packing
• Adhesive tape
• Culture swabs and vials
• Ultrasound machine with a 5 to 7.5 MHz probe
• Ultrasound probe covers
• Ultrasound gel
• Standoff pad
• Ultrasound probe cleaning and disinfecting solutions

Explain the procedure, its risks, and benefits to the patient and/or their representative. Patients should be warned of potential cosmetic complications prior to proceeding. Obtain an informed consent to perform the procedure. If endocarditis prophylaxis is indicated, oral regimens should be given 1 hour prior to the procedure and parenteral regimens within 30 minutes of the procedure (Table 106-1). Clean the skin of any dirt and debris. Apply povidone iodine or chlorhexidine solution to the skin and allow it to dry. Apply drapes to delineate a sterile field. Many Emergency Physicians regard this last step optional. The procedure of cutting into a contaminated abscess is considered to be clean and not sterile.

Anesthesia

It is usually possible to achieve adequate anesthesia for the skin incision but any additional manipulation may be painful. Local anesthetic infiltration is often less effective than in other procedures. The pH of infected tissue is often low and retards the diffusion of the local anesthetic solution into nerve axons.48 A regional field block can be instituted by injecting a ring of 1% lidocaine or 0.5% bupivacaine subcutaneously approximately 1 cm away from the perimeter of the erythematous border of the abscess. The onset of anesthesia occurs after about 5 minutes. A small amount of local anesthetic solution can be injected intradermally into the roof of the abscess in a linear fashion along the line of the planned incision (Figure 106-4A).4 Be careful during this portion of the procedure as the abscess may be under pressure. The inadvertent injection of local anesthetic solution into the abscess cavity may cause fluid to be forcibly ejected toward the Emergency Physician. Appropriate universal precautions should be employed including a face mask and eye protection.

In superficial abscesses or furuncles, which are unlikely to require significant exploration, topical ethyl chloride spray can be used to provide anesthesia. Invert the bottle and compress the spray nozzle to begin the flow of fluid. Direct the spray toward the planned site of incision. The pain relief from ethyl chloride is variable and fleeting. It is also highly flammable.5 The application of an ice pack over the planned incision site secured with an elastic bandage for 15 minutes can also be effective. This may be especially useful for children, those with severe needle phobias, or in cases of a true anesthetic allergy.

Nitrous oxide is safe and was previously thought to be effective as an adjunct to the incision and drainage of abscesses.49 More recently, it has been shown to cause no significant reduction in pain and to only be marginally effective as an anxiolytic.50 Procedural sedation with agents such as ketofol (ketamine and propofol in a 50:50 mixture in a dose of approximately 1 mL/kg IV in adults) can be useful in deep abscesses that require extensive probing.51 It is difficult to obtain adequate pain control in these cases, even with a well-performed field block.

Aspiration

Aspiration is performed as a diagnostic procedure in cases of soft tissue infections where the presence of an abscess is unclear, a mycotic aneurysm must be ruled out, or samples for Gram stain and culture are required. Aspiration is not a therapeutic procedure in and of itself. Anesthetize the skin. If ultrasound is available, locate the abscess cavity and try to determine the shortest needle path. Insert an 18 gauge needle attached to a 10 mL syringe into the skin. On ultrasound, the needle should appear as a bright, hyperechoic line with posterior reverberation artifact.42 As the needle penetrates deeper, it should become increasingly oblique. Apply negative pressure to the syringe. Advance the needle into the area where pus or blood is presumed to be loculated. The procedure should be terminated and incision and drainage should be performed immediately if pus is obtained on aspiration. Anaerobic and aerobic culture bottles should be inoculated directly from the syringe if cultures are indicated. Simple swabbing of the purulent material after incision and drainage is inadequate for growth of anaerobic organisms. If blood is aspirated, terminate the procedure and apply firm pressure to the area to prevent a hematoma from forming. Angiography with surgical consultation should immediately follow. If no pus or blood is aspirated, redirect the needle in several directions to confirm the absence of an abscess. Discharge the patient with oral antibiotics, warm compresses, and follow-up in 24 hours for a reassessment.

Incision and Drainage

Make an incision spanning the entire area of fluctuance and parallel to the relaxed skin tension lines to reduce scarring.35 A straight incision with a #11 scalpel blade is usually performed (Figure 106-4B). An elliptical incision with a #15 scalpel blade is an alternative and often results in a similar appearing final scar (Figure 106-4C). The purpose of the elliptical incision is to remove a full thickness wedge of tissue so that the wound will remain open. This type of incision should not be made in cosmetically sensitive areas (e.g., face, neck, or breasts) or in areas with minimal subcutaneous tissue (e.g., hands and feet). It is important to ensure a large enough incision to promote adequate drainage with the exception of cosmetically sensitive areas where a stab incision may be initially attempted to limit scar formation.5

Debride any necrotic or devitalized tissue. Probe the cavity by inserting a hemostat. Gently spread the jaws open to break up any loculations and to release any further pockets of purulent material (Figure 106-4D).6 Rotate the hemostat around the entire abscess to break any loculations. A scalpel should not be used for the blunt dissection of an abscess cavity as it may cause additional tissue damage and bacteremia.14 Remove the tough shiny capsule by grasping the edges with a hemostat and applying firm traction if the abscess is due to an infected sebaceous cyst. The capsule can often be removed intact.

Irrigate the abscess cavity with an 18 gauge angiocatheter attached to a 10 mL syringe containing sterile saline (Figure 106-4D). This will flush away all loosened purulent and necrotic material. Loosely pack iodoform gauze into the abscess cavity (Figure 106-4E). Leave 1 to 2 cm of gauze exiting from the cavity to prevent the incision from sealing over and ensure an adequate drainage tract for the cavity. The value of antiseptic impregnated gauze over plain gauze is uncertain. Do not over pack the abscess cavity as this may interfere with the inflammatory hyperemia necessary for healing or retard drainage and reproduce “abscess-like” conditions.6 Apply an absorbent dressing of 4 × 4 gauze over the wound. Splinting and elevation of the affected area may be beneficial in select patients (e.g., young patients and confused patients).

The majority of available evidence suggests that incision and drainage of subcutaneous abscesses alone is adequate treatment and additional antimicrobial therapy is unnecessary in healthy patients with no major comorbidities. Many recent studies involving abscesses, including those caused by MRSA, have demonstrated that patients have similar outcomes regardless of whether or not appropriate antibiotics were used after an abscess incision and drainage.17,24,52–54 A pediatric study demonstrated 94% resolution with incision and drainage alone in patients with abscesses smaller than 5 cm in diameter.52 Some conflicting evidence from a retrospective cohort found ancillary antimicrobial treatment active against MRSA had a resolution of 95% while those patients not receiving antimicrobial treatment had a resolution of only 87%.55

Consider empiric antimicrobial therapy active against MRSA in cases involving multiple lesions, cutaneous gangrene, immunocompromised patients, extensive surrounding cellulitis, systemic toxicity, unusual pathogens, and in patients requiring hospitalization.36,56 Further, recommendations from the Center for Disease Control suggest antibiotics after incision and drainage in those with rapid progression, comorbidities such as diabetes mellitus, HIV, neoplastic disease, those patients at extremes of age, abscesses in locations that are difficult to drain or have a risk of septic phlebitis associated with it, and lack of response to incision and drainage alone.19 Pediatric patients with abscesses greater than 5 cm should also receive empiric antimicrobial therapy.52

An oral antibiotic such as cephalexin can be a good first choice for healthy individuals in areas where the prevalence of MRSA is extremely low.19 Knowledge of local MRSA prevalence and antimicrobial susceptibility patterns are paramount when selecting the appropriate antibiotic.19,36 If more than 10% to 15% of community Staphylococcus aureus isolates are MRSA, empiric treatment with agents that show activity against MRSA is warranted.57 Current guidelines for outpatient therapy suggest using trimethoprim-sulfamethoxazole, Clindamycin, Doxycycline, Minocycline, or Linezolid. Rifampin can be added to many of these antimicrobials, but should not be used alone. IV therapy for patients with significant comorbidities and signs of systemic infection should include either Vancomycin, Daptomycin, Linezolid, or Tigecycline.22,56 Trimethoprim-sulfamethoxazole, Clindamycin, and Doxycycline (if over the age of 7 years) are recommended in healthy children.58 More serious infections should be approached with IV Vancomycin or Clindamycin, with the addition of nafcillin or gentamicin, and admission to the hospital.58 The addition of an agent active against Group A Streptococcus is also recommended in cases with a severe surrounding cellulitis.19 Current literature and consideration of the local antibiotic resistance patterns should guide antimicrobial selection.19,56,59

Follow-up in 24 to 48 hours to remove the packing and assess the response to therapy should be arranged. Pain can be adequately controlled with the use of acetaminophen or nonsteroidal anti-inflammatory drugs. Narcotic analgesics are rarely required. Instruct the patient to immediately return to the Emergency Department if they develop fever, chills, increased pain, increased swelling, or increased redness to the surrounding skin. Repack the cavity approximately every 48 hours until granulation tissue is developing throughout the wound and the drainage tract is well established if a large amount of drainage continues.15,60 At that time, the remaining packing is removed and the patient is instructed to soak the area in warm water three to four times per day.3 Healing occurs in 5 to 9 days in most cases.4,6,15 The patient may be discharged from medical care when all signs of infection (i.e., erythema, drainage, pain, and induration) have resolved.

It is currently standard practice to pack an abscess cavity after an incision and drainage. Packing is used for hemostasis, to keep the abscess cavity from closing prematurely, and to debride the abscess cavity. Packing an abscess cavity can be painful and requires multiple follow-up visits. These visits are at an additional cost to the patient. A small, prospective study of noncomplicated abscesses found not packing an abscess cavity resulted in less pain, less analgesic use, and no increased morbidity.62 Further studies are required before any definitive recommendation can be made regarding to pack or not to pack an abscess cavity.

Abscesses are currently allowed to heal by granulation. This process can take weeks and results in large scars. Primary suture closure after incision and drainage has been used around the world except in the United States.63,64 This treatment can reduce scarring, reduce pain, and promote faster healing. Most of the studies involve a small number of patients, administered preprocedural antibiotics, and were performed in the Operating Room. Further studies are required before this change in practice can be recommended for the Emergency Department management of abscesses.

The role of decolonization regimes after incision and drainage does not have established effectiveness.19 However, a decolonization regimen may play a role in those patients with recurrent infections, those not responding to therapy, or in patients with a closely associated cohort at risk (e.g., infirmed family, sports teams, or the institutionalized).36 A recent randomized controlled trial of 2% chlorhexidine gluconate wash, 2% mupirocin intranasal ointment and oral rifampin, and doxycycline for 7 days found that after 3 months, 74% of patients were free of MRSA colonization.61 This number dropped to 54% at 8 months post-treatment.61 Colonization rates vary by geography and colonization is considered a risk factor for MRSA infection. However, decolonization is not routinely recommended due to limited supporting evidence, poor patient compliance, and the risk of increasing antibiotic resistance.22

Patient education is the most effective way to reduce the spread of infection and recurrent infections from MRSA.19,22 Maintaining a clean and dry wound, frequent handwashing and bathing, avoiding sharing any personal items at all (athletic or otherwise), laundering clothing that has come into contact with the wound, avoiding skin to skin contact and disinfecting equipment and other surfaces are essential recommendations that should be made to outpatients with MRSA skin and soft tissue infections.19

Complications resulting from the incision and drainage of an abscess are uncommon. In most cases, some scarring will result from deliberate open packing and secondary intention granulation of the wound. Infectious complications, including inciting bacterial endocarditis as discussed earlier, are possible. Endocarditis can be avoided with appropriate screening of patients and the administration of prophylactic antibiotic therapy in patients at risk. Precipitation of septicemia because of transient bacteremia in an immunodeficient patient must be considered prior to the procedure. Incision and drainage of a mycotic aneurysm should not occur if an appropriate assessment is completed prior to making the incision.

Simple incision and drainage under local or regional anesthesia in the Emergency Department can effectively treat most subcutaneous abscesses. Adjunctive procedural sedation may be required to adequately probe a deep cavity. A directed history and physical examination will identify those who may require additional lab work, imaging, specialty consultation, and follow-up. The majority of patients will not require antibiotics, although there may be a role for ancillary treatment in selected patients with MRSA infections. Attention must be paid to requirements for endocarditis prophylaxis and consideration given to the possibility of inducing bacteremia in any given patient.