04. Incision & Drainage

Resident Editor: Izzy Marshall, MD

Faculty Editor: Paul Nadler, MD

Bottom Line: Most patients with skin abscesses should undergo incision and drainage. Patients with moderate-sized (<5 cm) abscess in low risk areas can be safely drained in primary care clinic. Patients with small abscesses that are spontaneously draining can be observed.  Antibiotics are indicated if there is overlying cellulitis or other risk factors, and can be used in all abscesses if the benefits exceed the (largely symptomatic) risks.

1. Background

  • Skin abscesses are collections of pus within the dermis and deeper skin tissues.  

2. Signs and Symptoms

  • Painful, tender, fluctuant and erythematous nodules surrounded by a rim of erythematous swelling

3. Differential diagnosis

  • Usually history and exam are sufficient to distinguish skin abscesses from other conditions, where I&D is not indicated.
  • DO NOT DO INCISON AND DRAINAGE OF:
  1. Vascular malformation
  2. Kerion – a boggy, tender exudative scalp mass in a patient with tinea capitis
  3. Herpetic whitlow – HSV infection of the finger
  4. Hidradenitis suppurativa – recurrent furuncules in areas with apocrine glands

4. Evaluation

  • A clinical exam in the office is sufficient for most patients. Bedside ultrasound may be helpful for identifying the presence or size of an abscess, assess for interconnected abscesses, determine the location of the largest purulent collection prior to incision, and to assess for incomplete drainage if an abscess fails to resolve.

​5. Treatment:

PROCEDURE
  1. Preparation
  • Explain the procedure to the patient, explain risks and benefits, and obtain verbal informed consent
  1. Gather Supplies
  • Sterile gloves (preferred), eye protection, sterile drape (if applicable), gauze
  • Povidone-iodine (or equivalent)
  • 1% lidocaine, 25 g needle, 20 g needle and 3 to 10 mL syringe
  • Scalpel with 11 blade (number 15 blade acceptable), curved hemostat
  • Normal Saline syringe(s) with catheter or needleless irrigation device
  • Packing material (1/4 or ½ inch iodoform or plain gauze packing tape)
  • Sterile gauze 4x4, Tegaderm, paper tape
  • Culture swab (if applicable)
  1. Infiltrate Local Anesthesia

Using sterile gloves, clean the area with povidone-iodine and then inject 1% lidocaine along incision line or perform field block. (Lidocaine toxic dose 4mg/kg, Lidocaine with epi toxic dose 7mg/kg)
  1. Incision and drainage
  • Using a scalpel with a number 11 blade, make a simple linear incision at the point of maximal fluctuance and through the length of the abscess
  • Obtain a culture of drainage fluid if indicated*
  • Bluntly probe the abscess cavity with a curved hemostat or swab to remove any foreign bodies and to break up loculations
  • Copiously irrigate the abscess cavity with normal saline
  • Pack all larger abscess with sterile packing gauze or iodoform and consider packing smaller abscesses if it will accommodate packing.  Do not “overpack”.
  • Most abscesses should heal by secondary intention and not be closed by suture.  Cover the wound with dry gauze and Tegaderm
  • Prescribe antibiotics if indicated**
  1. Follow-Up
  • Schedule a wound check within 24 to 48 hours
  • At the follow up remove the packing (if present).
  1. If drainage has stopped then instruct the patient to start warm wet soaks (soapy water) 3-4 times per day and do not repack the wound.  Ask the patient to return to clinic only as needed.
  2. If drainage persists then repack the wound and have the patient return in 24 to 48 hours for a wound check. Repeat this step until the drainage has stopped.

* Indications for obtaining a culture

  1. For patients who will be treated with antibiotics and have the following:
    1. Systemic signs of infection, history of recurrent abscesses, failure of initial antibiotic therapy, immunocompromised, elderly

** Indications for antibiotics

  1. The IDSA guidelines published in 2014 recommend antibiotics only for patients with signs of systemic infection, surrounding cellulitis, larger abscesses (>2cm), major co-morbidities (e.g. uncontrolled diabetes, others?), presence of an indwelling medical device, high risk for poor outcomes with infective endocarditis (history of IE, prosthetic valve, unrepaired congenital heart disease) or immunocompromising condition 
  2. However, 2 recent clinical trials have demonstrated that adjunctive antibiotics increase clinical cure rates for abscesses, including smaller ones (<5 cm) and to decrease the risk of recurrence
  3. Bottom line: Consider antibiotics for all patients. Prescribe a 5-day (up to 14 days in complicated patients) course of oral anti-MRSA coverage such as trimethoprim-sulfamethoxazole 2 DS tabs BID or doxycycline 100 mg tabs BID or clindamycin.

6. Observed Patients (small abscesses spontaneously draining):

  1. Apply warm compress to the infected area 3-4 times per day to promote drainage
  2. If no improvement after 48 hours, consider treating with an oral antibiotic with activity against MRSA.

7. When to Refer

  1. Abscess location: these abscesses have a high rate of complications and require referral to a surgeon, or to the ED if specialty care not immediately available
    1. Perirectal abscesses
    2. Peritonsillar abscesses
    3. Anterior and lateral neck abscesses potentially arising from congenital cysts (e.g. Thyroglossal duct cyst, brachial cyst, cystic hygroma)
    4. Hand abscesses (excluding paronychias and felons)
    5. Abscesses adjacent to vital nerves or blood vessels (eg. Facial nerve, femoral artery)
    6. Breast abscesses, particularly those near the areola
    7. Abscesses in the central triangle of the face (risk of septic phlebitis and intracranial extension)
  2. Abscess > 5 cm by palpation or U/S
  3. Recurrent and multiple interconnected abscesses

References

  1. Talan DA, Mower WR, Krishnadasan A. Trimethoprim-Sulfamethoxazole for Uncomplicated Skin Abscess [Letter]. NEJM. 2016;375:285-6. [PMID: 27468069]
  2. Daum RS, Miller LG, Immergluck L, Fritz S, Creech CB, Young D et al. DMID 07-0051 Team. A Placebo-Controlled Trial of Antibiotics for Smaller Skin Abscesses. NEJM 2017; 376:2545-2555
  3. Ramakrishnan et al. “Skin and Soft Tissue Infections.” Am Fam Physician. 2015 Sept. 15;92(6): 474-483.
  4. Downey et al. “Technique of incision and drainage for skin abscess.” UpToDate. Last reviewed Oct 02, 2017.
  5. Bystritsky R, Chambers H. “Cellulitis and Soft Tissue Infections.” Annals of Internal Medicine. 2018; ITC 18-31.