Perineal Abscess Drainage

Background

An abscess is an infectious process characterized by a collection of pus surrounded by inflamed tissue.[1, 2] Abscesses can form anywhere in the body, from a superficial skin (subcutaneous) abscess to deep abscesses in muscle, organs, or body cavities. Patients with subcutaneous skin abscesses present clinically as a firm, localized, painful, erythematous swelling that becomes fluctuant (see the image below).

The abscess cavity is formed by necrosis of the subcutaneous tissue and is filled with debris from surrounding tissue, white blood cells, blood and plasma products, and bacteria. The wall of the abscess is made up of dermis infiltrated with inflammatory cells surrounded by a fibrinous capsule.[1] Fevers, chills, and other constitutional symptoms are usually absent unless the infection has spread to deep tissues or into the bloodstream.[2]

An abscess must be distinguished from cellulitis as treatment differs between the two. In contrast to an abscess, soft tissue affected by cellulitis is viable with intact blood supply. The infection usually affects more superficial tissue. Cellulitis resolves with appropriate antibiotic treatment alone if initiated before tissue necrosis occurs. A deep abscess can be mistaken for cellulitis as fluctuance may be harder to appreciate.

Treatment of an abscess is always drainage; the infection will not resolve unless the pus is drained. The abscess cavity is avascular and therefore antibiotic treatment alone will not resolve the infection.[1, 3] If left untreated, an abscess can progress in involve deeper tissue and has the potential to develop into a life-threatening, systemic infection.

Formation of subcutaneous abscesses can occur anywhere on the body but frequently occurs in intertriginous, hair-bearing areas, such as the groin. It is usually the result of direct extension of an infection of the dermis or epidermis (ie, furuncle, carbuncle, folliculitis, cellulitis) by normal skin flora.[4, 2] Perineal abscesses are typically polymicrobial containing mixed aerobic and anaerobic gram-negative organisms. Common organisms include Staphylococcus aureus and group A ß-hemolytic streptococci (normal skin flora isolated at all body sites) and enteric gram-negative bacilli and Bacteroides fragilis group (gastrointestinal flora).[1, 4, 5]

Indications

Drainage is indicated for any subcutaneous infection with a fluid-filled, necrotic central cavity. There are no contraindications.

Anesthesia

Many abscesses can be drained at the bedside under local anesthesia. Typical anesthetic agents include ¼% Marcaine or 1% lidocaine with or without epinephrine. Epinephrine can be used to decrease the amount of bleeding at the incision site. Inject the skin surrounding the abscess cavity instead of the cavity itself. Injecting anesthetic into the abscess cavity will result in inadequate anesthesia.

In cases in which the extent of the abscess cavity cannot be elucidated at bedside, or where the pain is too great to perform drainage under local anesthesia, examination and drainage in the operating room under sedation or general anesthesia is necessary.

Personal protective equipment

• Gloves

• Face shield

• Gown

Anesthetic

• Topical anesthetic

• Syringe, 10 mL

• Needle, 27 gauge

• Needle, 18 gauge

Site preparation

• Skin prep

• Sterile towels

Instruments

• Scalpel

• Forceps

• Swabs for wound culture

• Irrigation

• Sterile gauze for packing

Positioning

Position is determined by location. Depending on what provides maximal exposure, the patient may be prone or supine. Dorsal lithotomy provides good exposure for most perineal lesions.

Approach

The goal of treatment is to remove all necrotic debris and pus from the abscess cavity. Opening the abscess widely to allow all contents to drain is important. The wound should remain open after the procedure and be allowed to heal by secondary intent. This is accomplished by packing the wound and changing the packing frequently. Primarily closing the wound results in reaccumulation of the infection. Broad-spectrum intravenous antibiotics are often administered preoperatively. Postoperative antibiotics are tailored according to the culture result.

Procedure

Steps in the procedure are listed below:

• Prep and drape in a sterile fashion maintaining adequate exposure to the site.

• Draw local anesthetic into the syringe using the 18-gauge needle and inject skin surrounding the abscess using the 27-gauge needle.

• Make an incision directly over, extending the entire length of the area of greatest fluctuance.

• Use forceps to stretch open the incision, allowing the contents of the cavity to drain. Insert finger or forceps into abscess cavity to break up any loculations.

• Flush cavity with irrigant. Irrigant options include vancomycin, gentamicin, hydrogen peroxide, iodine, Hibiclens, sterile water, or saline. This can be accomplished using a syringe, spray bottle, or a Pulsavac.

• Pack abscess cavity with sterile gauze. Alternatively, a Penrose drain may be left in place and the skin closed primarily.

A study by Chinnock et al reported that irrigation of the abscess cavity during incision and drainage did not decrease the need for further intervention.[6]

Complications

As with any surgical procedure, bleeding is always a complication. Major bleeding is extremely rare owing to the superficial location of these infections.

The site is already infected by definition; therefore, introducing infection is not a concern, although spreading the infection into surrounding tissues is a risk. This can be minimized by limiting the trauma to local tissues.

Disposition

This may be an outpatient procedure. If signs of systemic infection or complications from the procedure such as excessive bleeding exist, hospital admission may be necessary.

Wound care

Dressings should be changed wet to dry twice a day until the wound has healed. The wet-to-dry dressings serve to debride the wound. A number of debridement methods are available; dressing changes suffice for most wounds.[7] Sitz baths should be performed 3 times a day for at least the first week after surgery. Large wounds may be better managed with a Wound V.A.C. or may require a wound care consultation.

Pain management

Oral pain medication is used for pain management in the postoperative period. Generally, the pain caused by the abscess is relieved with treatment and minimal pain management is required.

Postoperative antibiotics

Postoperative antibiotic therapy is determined from the results of the wound culture. Although most would probably treat with a course of antibiotics postoperatively, some debate exists as to whether or not uncomplicated abscesses require antibiotic treatment after drainage. Two placebo-controlled trials funded by the National Institutes of Health (NIH) addressed this question.[8, 9, 10]  Neither study showed a significant difference in the short-term response rate with regard to the primary lesion. Another randomized, controlled trial funded by the NIH found that in areas with a high prevalence of community-acquired methicillin-resistant Staphylococcus aureus, patients with a drained cutaneous abscess who received trimethoprim-sulfamethoxazole had a higher cure rate than those who received placebo.[11]

Follow-up

Patients will follow up in clinic 1-2 weeks after drainage, and thereafter until the wound heals completely. Wet-to-dry packing should continue until the cavity no longer accommodates packing. At that time, dry dressings suffices until complete healing occurs.