Perianal and Perirectal Abscesses Treatment & Management

Treatment of both perianal abscess and fistula-in-ano remains controversial. Antibiotics were originally believed to play a limited role in the primary therapy of perianal abscesses but were frequently initiated by pediatricians prior to surgical referral. The concept that abscesses must be drained in order to heal is as close as one can find to a universally accepted incontrovertible surgical law. Such thinking perpetuates dogma and stifles advances in care. A recent study has brought into question the benefit to draining perianal abscesses and the potential advantage to treating with antibiotics alone.^[3] The data presented in this article support the idea that not draining abscesses in otherwise healthy babies decreases the risk of fistula formation and that adding antibiotics further decreases the risk.

Once a fistula has formed, the treatment is also controversial. Historically, babies with fistula-in-ano were treated identically to adults and underwent surgical fistulotomy; in some cases, such patients underwent seton placement. Recent evidence has shown that this procedure is largely unnecessary and may be reserved for the rare cases that fail to resolve after a sufficient period of nonoperative management.^[4]

Older children with no evidence of IBD can be treated with the approaches described above, with more aggressive intervention added if symptoms persist or worsen. Children in whom IBD is suspected should undergo evaluation for that condition.

It is important to note that the treatment strategies described have evolved in the direction of less-aggressive intervention. However, this should not be confused as adopting a more conservative approach. The term conservative, with respect to therapy, should be reserved for treatments that are tried and true and that are known with almost certainty to yield a positive outcome. Conservative treatment of an abscess is drainage. When first proposed, nonoperative treatment of a small perianal abscess in an otherwise healthy baby was considered radical. Time, experience with a large number of patients, and a supporting body of literature are required to take a radical therapy and transform it into a conservative therapy. The terms radical and conservative have nothing whatsoever to do with how much physician intervention and treatment is required, be it surgical or nonsurgical.

This understanding is critical for the treatment of children with perianal abscess and fistula. If a child of any age is ever appearing sick or toxic, the treatment should revert to the most conservative management possible. This would include the addition of antibiotics if they had been withheld thus far, the drainage of any abscesses, and the search for deep infection in the ischiorectal fossa via CT scanning. Such deep infections occur in the adult population but are virtually unheard of in pediatrics.

Antibiotic therapy

Controversy exists regarding the use of antibiotics in the treatment of perianal abscesses. Traditional teaching holds that drainage alone is sufficient for abscess treatment in otherwise healthy patients. A 2007 study by Christison-Lagay et al demonstrated that antibiotic use for perianal abscess decreased the likelihood of fistula formation.^[3]

All immunocompromised patients with infections should receive antibiotics as a component of their therapeutic plan. Patients with Crohn disease require antibiotic therapy in addition to the medical therapy used to treat their Crohn disease.

Perianal abscesses often grow mixed flora and can be well covered by various antibiotic choices. Common oral regimens for routine infection include cephalexin or amoxicillin-clavulanic acid. Methicillin-resistant Staphylococcus aureus (MRSA) is rarely implicated in perianal abscesses but should be considered as a pathogen in patients who are not responding to traditional antibiotic choices. Trimethoprim/sulfamethoxazole is available in liquid form and can cover MRSA.

Abscess

The surgical treatment of perianal abscess is incision and drainage. Most babies can easily undergo this procedure in the office.

Fistula

The surgical treatment of fistula-in-ano is fistulotomy. This requires anesthesia and takes place in an operating room.

Patients with Crohn disease rarely undergo fistulotomy; instead, they usually undergo a similar procedure to identify the fistulous tract and to place a noncutting seton (often a long soft rubber or silicone band called a vessel loop, used in vascular surgery to isolate blood vessels) through the tract in order to facilitate drainage and to help control the localized sepsis. Other procedures eventually follow but are more complex and beyond the scope of this article.

The use of cutting setons has been largely abandoned in the pediatric population. In this technique, the concern is that cutting open the fistulous tract will cut the sphincter and risk incontinence. This was of major concern for large high fistulas that track above the sphincter (referred to as supra-sphincteric fistulas). To use a cutting seton, a thick suture (the seton) is placed through the fistulous tract and tied to itself. It is then tightened progressively over several weeks so that it slowly cuts through the tissue while allowing scar tissue to form on the other side of the cut so that at no point is the sphincter cut completely open. This is a painful technique that has proven essentially unnecessary in the pediatric population.

Fistulectomy is a procedure whereby the entire tract tissue is stripped out, either by surgical means or by the use of fistulotomy and curettage. This procedure is not required in the pediatric population.

No preoperative preparation is required for simple abscess drainage in otherwise healthy children.

Children undergoing general anesthesia should avoid eating solid food for at least 8 hours prior to surgery.

Surgeons may require some form of bowel preparation to clean the anus and rectum in preparation for a fistulotomy.

Abscess drainage

• A dependable assistant is required to hold the child still. The procedure is rapid but is not possible without an experienced pediatric assistant who can firmly hold the baby motionless for the few seconds that sharp items are being used.
• The area over the abscess is swabbed with Betadine or an equivalent skin preparation solution.
• The skin immediately overlying the abscess is anesthetized using a tuberculin syringe and local anesthetic to raise a small wheel. This step is debatable, as some believe that the pain caused by the incision is equivalent to the pain caused by the local anesthetic. The authors prefer to use local anesthesia.
• An 11-blade scalpel is used to make an incision directly into the abscess. Pus is then expressed. A simple incision is sufficient, and no packing is required.
• Once the pus is drained, the remaining local anesthetic in the syringe can serve as a skin wash, and a dry gauze is applied. There is usually only minor bleeding, which is controlled well with just a few minutes of pressure. Once the procedure is concluded, the best analgesia is to return the infant to the arms of a parent.

Fistula

• The patient is positioned in the lithotomy position.
• After being fully anesthetized, the fistulous opening is identified within the anal canal, either via gentle probing of the skin opening with a lacrimal probe or through the use of anoscopy.
• Once identified, a probe may be passed through the entire length of the fistula from the skin side all the way into the anal lumen. The fistulous tract is then opened up completely by cutting the tissue between the anal lumen down to the probe, so that the probe is free and within the anal lumen. The cut may be made with a fine needle-tip electrocautery to aid in hemostasis. Once the probe is free and the fistulous tract therefore completely opened, the procedure is complete.

Following perianal abscess drainage, acetaminophen may be useful for postoperative pain, but most patients feel better once the pus is no longer under pressure.

Parents should be counseled that a drop of blood in the diaper or dressing is not unusual but that persistent bleeding is a problem and requires pressure and perhaps a return to the office.

Following abscess drainage, babies should undergo a brief warm bath after every bowel movement to ensure that the area is being adequately cleaned.

The opening often closes within several days and resolves completely, but many patients who undergo drainage eventually form a fistula.

Older children who undergo abscess drainage or fistulotomy should take a sitz bath (to sit and dunk the bottom in a warm tub, traditionally with Epsom salts, but not required) after every bowel movement, a minimum of 2-3 times each day.

Dressings are required as only long as the opening is draining. Panty liners make excellent dressings and have an adhesive strip that holds them in place in the underwear.

All patients receiving antibiotics alone require close follow-up and should be seen a few days after therapy is initiated and then weekly until the infection is completely resolved.

Patients who underwent surgical drainage of an abscess should be seen weekly until the abscess is completely resolved and the skin opening healed. Thereafter, the authors choose to see these patients every 3 months until at least 6 months have passed without any evidence of the hole reopening as proof that a fistula has not formed.

Patients who underwent surgery for a fistula need acute and long-term follow-up similar to those who underwent acute abscess drainage.

Because the likelihood of recurrent abscess and fistula formation is high even after adequate surgical drainage, surveillance is necessary. Complex or nonhealing perianal abscesses and fistulas may be signs of Crohn disease. Chronic drainage or recurrent abscess may indicate a fistula.

Complications are extremely rare in the otherwise healthy patient, and are most commonly associated with Crohn disease, neutropenia, or an immunocompromised state.

The prognosis of perianal abscess in children is excellent for all cases unrelated to Crohn disease. With or without surgery, the condition will eventually be brought to a successful resolution with no impact or implications for the future.

Children with abscesses who undergo drainage are likely to develop a fistula.

Fistulas in children usually self-resolve, but some require surgery for resolution. Recurrent fistula following fistulotomy in an otherwise healthy child is very unlikely and should prompt an evaluation for other signs of Crohn disease.

The prognosis of Crohn-related perianal pathology is complex and beyond the scope of this article.

Controversies abound in the treatment of perianal and perirectal abscesses.

The use of antibiotics alone (rather than surgical drainage) as a means of definitive treatment with the intent to decrease the likelihood of eventual fistula-in-ano formation is quite controversial but supported in the literature.^[3]

The nonoperative management of fistula-in-ano via observation alone in otherwise completely health male babies remains controversial but is also supported in the literature.^[4]