Acquired Anorectal Disorders
Perianal and Perirectal Abscess
Perianal or perirectal abscesses are often encountered during infancy. The abscess typically presents as a fluctuant, tender mass in the perianal region (Fig. 37-1). A history of stool abnormalities is typically not elicited. Perianal abscesses are much more common in male infants and are infrequent in toddlers and older children.1 Crohn disease, immunodeficiency, glucose intolerance, and perianal trauma can be causative stimuli in the older child. It is unusual to find complex ischiorectal abscesses in children unless associated with inflammatory bowel disease (IBD).
FIGURE 37-1 Perianal abscesses are often seen in male infants. The abscess typically presents as a fluctuant, tender mass in the perianal region. Incision and drainage is the initial management of these abscesses.
For the infant, sitz baths are prescribed if the abscess does not appear to be fluctuant. Approximately one-third of abscesses thus treated resolve without recurrence.2 Approximately two-thirds require incision and drainage. Although drainage can be accomplished in the infant without general or topical anesthesia, we prefer a brief inhalational anesthetic to allow for adequate drainage and optimal patient comfort. Considerable debate exists with regard to making an effort to delineate a fistula at the time of abscess drainage, yet we prefer simple abscess drainage as the initial step.3,4 The patient begins sitz baths on the first postoperative day, and oral antibiotics are not needed once the abscess has been drained.
Fistula-In-Ano
As many as 50% of perianal abscesses progress to a fistula-in-ano.5 The child is usually seen after two or more ‘flare ups’ of a perianal abscess that either continues to drain or forms a small pustule that ruptures, only to form again (Fig. 37-2).6 The fistula is commonly located lateral to the anus rather than in the midline. An intriguing theory has been suggested that fistula-in-ano results from infection in abnormally deep crypts that are under the influence of androgens. The fact that fistula-in-ano rarely follows a perianal abscess in female infants lends credence to this theory.7
FIGURE 37-2 As many as one-half of the perianal abscesses progress to a fistula-in-ano. In this photograph, the fistula is seen at 1 o’clock when the infant is in the lithotomy position.
Our preferred operative technique for a fistula-in-ano is fistulotomy which is described within the caption of Figure 37-3. Following the procedure, we instruct the parents to place the infant in a sitz bath after each bowel movement, at least twice daily, and to separate the skin edges of the fistulotomy during bathing to promote healing by secondary intention. We reserve cryptectomy for patients with recurrence, which is rare after an adequate fistulotomy.
FIGURE 37-3 (A) At the time of operation, a small, fine, malleable probe is inserted through the fistula and can usually be gently advanced until it is visualized to exit the base of the involved crypt. (B) An incision is then made along the probe and is deepened through the superficial portion of the external sphincter. (C) After complete unroofing of the tract, the incision is usually left open, which may provide some distress on the part of the parents but usually does not cause much discomfort for the child.
Anal Fissure
An anal fissure commonly develops in a toddler whose diet changes from liquid to solid and whose stool consistency changes from soft to firm. A period of constipation results in a posterior midline tear in the anoderm below the mucocutaneous junction. The discomfort with defecation leads to further constipation, which aggravates the fissure and prevents healing. The diagnosis is made with a history of hematochezia, the child’s crying during bowel movements, and the recognition of a split in the anoderm. Operative interventions such as lateral internal sphincterotomy or fissurectomy are rarely necessary.8,9 We prefer sitz baths and an osmotic stool softener, such as polyethylene glycol, which usually results in healing.
For older children without evidence of IBD, topical 0.2% nitroglycerin ointment can be used. However, the collective evidence for utilizing topical glyceryl trinitrate suggests that this treatment is no better than placebo.10 Chemical sphincterotomy using Botulinum toxin is employed when nonoperative interventions have failed. We prefer a total of 25–50 units of Botulinum toxin A prepared in sterile saline. This volume is divided into four aliquots and injected into the sphincter complex in four circumferential quadrants.
An anal fissure in an older child or a teenager may be associated with Crohn disease.11 Immunomodulatory treatment of Crohn disease typically results in healing of the fissure.12,13 Topical application of tacrolimus ointment is a promising relatively new therapy.14 Internal sphincterotomy appears to be a relatively safe undertaking in this patient population, but only when local measures and immunomodulator therapy have failed.15
Anal Skin Tags, Hemorrhoids, and Other Perianal Vascular Lesions
A perianal skin tag is rarely an indication of other disease, although it may result from a healed fissure (Fig. 37-4). Although it is generally of no consequence, when large enough it can be bothersome and can affect adequate perianal hygiene. In these cases, local excision is reasonable.
FIGURE 37-4 This 1-year-old developed this anal skin tag secondary to constipation. Due to its size, it was excised.
Hemorrhoids are uncommon in the pediatric population, and rarely is operative therapy a necessary aspect of treatment. External hemorrhoids are located in the distal one-third of the anal canal and covered by anoderm. Symptoms from external hemorrhoids are generally due to thrombosis, and examination reveals a tender, bluish mass at the mucocutaneous junction (Fig. 37-5). Treatment consists of incision of the hemorrhoid and extrusion of the clot with subsequent sitz baths, dietary modification (fiber supplementation), and stool softeners. Internal hemorrhoids are extremely rare in children unless associated with portal hypertension. The treatment for bleeding from internal hemorrhoids due to portal hypertension should be aimed at decreasing portal pressure, either pharmacologically or surgically. In patients without portal hypertension, initial treatment of internal hemorrhoids should be focused on conservative measures such as the provision of stool bulking agents and topical treatment (sitz baths and topical pharmaceutical preparations). Rubber band ligation or operative hemorrhoidectomy is performed when conservative measures fail.
