Rudolph's Pediatrics, 22nd Ed.

CHAPTER 416. Other Anorectal Disorders

Judith M. Sondheimer

HEMORRHOIDS AND ANORECTAL VARICES

Internal hemorrhoids are masses of vascular tissue covered by rectal mucosa. They arise from the superior hemorrhoidal plexus and lie above the pectinate line (eFigs. 416.1 and 416.2 ). External hemorrhoids arise from the inferior hemorrhoidal veins lying below the pectinate line and are covered by skin (eFig. 416.3 ). Hemorrhoids are rare in children and are usually external, associated with chronic constipation.1When engorged by straining, they appear as pearly gray or purple masses at the anal verge that occasionally bleed a small amount. They may become firm and painful when thrombosed or infected, conditions more common in adolescence than infancy. Hemorrhoids may be a sign of childhood sexual abuse. Symptoms from hemorrhoids usually improve with treatment of underlying constipation. Incision and evacuation of thrombosed or infected hemorrhoids may be necessary, but stool softeners, warm sitz baths, and antibiotics are often sufficient therapy.

Anorectal varices are found beneath the rectal mucosa or in the anal canal. These high-pressure venous channels shunt blood from the portal venous circulation (ie, superior hemorrhoidal vein) to the systemic circulation (ie, external iliac vein) in response to portal hypertension. One third of children with portal hypertension have hemorrhoids, 35% have anorectal varices, and 15% have isolated external anal varices. Occurrence is related to the duration and severity of portal hypertension.2 Rectal varices occasionally cause bleeding, but other symptoms are rare. Injection sclerotherapy or banding of varices is occasionally required in patients with severe portal hypertension and bleeding.

RECTAL PROLAPSE

Prolapse is the protrusion of one or all layers of the rectum through the anus.3 Isolated mucosal prolapse is common and appears as a red-purple, cylindrical protrusion from the anus of variable length, with radial folds extending from a central lumen at the leading point. Prolapsed mucosa may bleed and may secrete copious mucus. Anal pain may result from anal sphincter spasm. Children often complain of a mass in the anus after defecation that they cannot expel. Transient minor prolapse of rectal mucosa is common after defecation. Prolapse that includes mucosal, muscular, and serosal layers of the rectum (procidentia) is rare in childhood. It presents as a beefy red protrusion with circumferential folds caused by contractions of the circular musculature of the prolapsed rectum (Fig. 416-1).

Factors associated with mucosal prolapse are age < 2 years, constipation, acute diarrhea, malnutrition, heavy parasitic infestation, chronic cough, generalized or isolated perineal motor weakness, spina bifida, rectal polyps, solitary rectal ulcer syndrome, exstrophy of the bladder, and high imperforate anus repair. Although about 20% of patients with cystic fibrosis experience a rectal prolapse at some time, cystic fibrosis is not the most common cause of childhood rectal prolapse. In one study, 28% of children with prolapse had chronic constipation, 20% had acute diarrhea, 11% had cystic fibrosis, 24% had neuromotor problems, and 16% had no identifiable cause.

Most mucosal prolapses reduce spontaneously. Occasionally, gentle pressure on the external mucosal mass is needed to reduce prolapse. A prolapse that cannot be reduced manually even with sedation, may require surgical reduction. The anus may gape for up to 1 hour after prolapse reduction, and reprolapse may occur. Pressures in the anal sphincters are usually normal in patients with prolapse except in those with prior surgical procedures on the anus or with neuromotor disorders. Flexible sigmoidoscopy in patients with recurrent prolapse may reveal a lead point causing straining, such as solitary rectal ulcer or juvenile polyp. Barium defecography may show rectorectal intussusception during defecation, which is thought to cause straining and promote prolapse. Solitary rectal ulcer syndrome presents with symptoms of bleeding, passage of mucus and straining on defecation, tenesmus, perineal and abdominal pain, sensation of incomplete defecation, constipation, and rectal prolapse.4 The etiology of the rectal ulcer is unclear, but it seems likely that it results from ischemic changes in the rectum associated with paradoxical contraction of pelvic floor and external anal sphincter muscles and rectal prolapse, even if the prolapse does not penetrate through the anus.

FIGURE 416-1. Rectal prolapse.

Treatment of underlying pathology is indicated, with special attention to the treatment of constipation and straining. Surgery rarely is needed to correct rectal prolapse. However, in resistant cases of mucosal prolapse, submucosal injection of a sclerosant such as clove oil may be effective therapy.

ANAL FISSURES

Anal fissures are slit-like tears of the anal canal, usually located on the posterior or anterior anal verge and most commonly caused by the passage of large bowel movements. Other causes of anal fissures include crypt abscess, explosive diarrhea, perianal dermatitis or infection, inflammatory bowel disease, trauma, and sexual abuse. The most common symptoms of anal fissure are pain and scant bright red rectal bleeding on defecation. Anal fissure is the most common cause of rectal bleeding in infants. Inspection of the anus with gentle spreading of the buttocks usually is sufficient to reveal a fissure (eFig. 416.4 ); occasionally, proctoscopic examination is necessary to identify fissures in the anal canal.

Treatment of constipation with stool softeners, warm sitz baths, and lubrication of the anal skin generally is sufficient to produce healing. Anal dilation either digital or by dilator, relieves anal spasm and pain and promotes healing. A small pucker (sentinel tag) often occurs in the anal skin at the site of a healed fissure. Fissures or tags are seen in up to 30% of older children with retentive constipation. Anal fissures that do not heal should raise the suspicion of Crohn disease.5 Multiple anal fissures, or fissures associated with other signs of anal or genital trauma, must be investigated as signs of sexual abuse.6 In rare cases, silver nitrate cauterization, perianal injection of botulinum toxin A, or surgical resection of the fissure may be necessary. Surgery for fissures and perianal disease caused by Crohn disease should be avoided because healing may be very poor.

CRYPTITIS, ANAL ABSCESS, AND FISTULA

Infection of the crypts of Morgagni (cryptitis) is common. In children wearing diapers, it is most likely the result of lengthy fecal exposure. In older children, it is associated with chronic diarrhea and chronic constipation. Symptoms include anal pruritis or burning, pain on defecation, and scant rectal bleeding. Rectal examination is painful because of sphincter spasm. At sigmoidoscopic examination, the crypts of Morgagni are deep, with red, swollen anal columns.

Cryptitis increases the risk of perianal abscess. The mechanism of anorectal abscess and fistula formation is shown in eFigure 416.5 . Infection in crypts or the anal glands penetrates into the space between the internal and external sphincter or into the ischiorectal fossa and eventually may point on the perianal skin. The common causative organisms are Escherichia coli, anaerobes, and occasionally, Staphylococcus aureus. Boys are affected more often than girls, especially before 6 months of age.

Abscesses present with a tender, erythematous perianal lump that causes pain on defecation, constipation, or purulent discharge. Evaluation requires a careful rectal examination and search for a fistulous tract connecting the abscess to the anal gland or the crypt. This may require examination under anesthesia. Medical therapy includes warm sitz baths, stool softeners, and antibiotics. Incision and drainage is often performed as primary therapy; however, in infants a recent retrospective study found that 60% of those treated primarily by incision and drainage developed postoperative fistulae, while only 16% of those treated medically did so.6

In patients with recurrent abscesses or chronic drainage, identification of the fistula with surgical excision of both the fistula and the crypt of origin must be performed.7 Perianal abscess or fistula may be the presenting signs of Crohn disease in older children. Surgery in these children should be avoided as it is frequently associated with worsening perianal disease. Metronidazole or infliximab (in resistant cases) is used in children with perianal Crohn disease.5 The differential diagnosis also should include immune deficiency and malignancy, especially leukemia.

PRURITUS ANI

The most common cause of perianal itching in childhood is perianal dermatitis or infection. Pruritis after a course of broad-spectrum antibiotics is common and probably results from cutaneous overgrowth of Candida. Atopic dermatitis, seborrhea, contact dermatitis, perianal streptococcal infection, psoriasis, anal fissures, and lichen sclerosus et atrophicus cause pruritis. Culture or biopsy of the perianal skin may be necessary to identify rarer conditions when conservative therapy fails. Fecal or urinary incontinence or poor hygiene may cause maceration and dermatitis of the perianal skin with pruritus. Parasites such as pinworms, tapeworms, Trichomonas, scabies, and body lice may cause perianal pruritis. Diabetes mellitus, uremia, cholestatic liver disorders, urinary tract infection, and vaginitis all cause perineal itching. Foods containing chemical irritants or histamine releasers such as coffee, tea, wine, chocolate, colas, citrus, rhubarb, tomatoes, and peppers may cause irritation of the perianal skin during defecation. Perianal scratching may be a symptom of anxiety. Lichenification of the perianal skin by scratching perpetuates the sensation of pruritis.

A careful history and thorough physical examination, including a rectal examination, are key to diagnosis. Testing may include stool examination, pinworm prep, urinalysis, urine culture, and culture or biopsy of dermatitis. Specific treatment of pruritus ani depends on the cause, but general measures include good perianal hygiene, local emollients, loose cotton underclothing, and prevention of scratching.

ANORECTAL DISORDERS IN SEXUAL ABUSE

Anal assault is a major cause of the injuries associated with sexual abuse (see also Chapter 35). In a recent review of 310 childhood victims of sexual abuse, abnormalities of the anus were identified in 104 (34%). These included gaping of the anus (61 children), anal tags (44), anal fissures (33), sphincter rupture (15), condylomata acuminata (4), scarring (2), and bites (1). Other findings consistent with chronic anal penetration include anal vascular congestion and hemorrhoids; thickening, erythema, and hyperpigmentation of the anal skin; and shortening of the anal canal.8,9 Other conditions producing a lax anus include meningomyelocele, surgical repair of Hirschsprung disease or imperforate anus, neuromotor conditions such as myotonic dystrophy and muscular dystrophy, and inflammatory bowel disease. Visible laxity of the anus is rare in children with retentive constipation.

Anogenital infection may be a sign of sexual abuse. Anogenital infection with human papillomavirus may also be acquired at birth or postna-tally from an infected mother (see Chapter 233). Specific typing of the virus in the patient and caregiver may clarify the source of infection.10 The older the child at the appearance of genital warts, the higher the likelihood that acquisition is by sexual contact. Herpetic lesions may be spread from an infected caretaker or by autoinoculation from oral lesions. The simultaneous presence of anogenital warts or herpetic lesions with other sexually transmitted infections (eg, Trichomonas, gonorrhea, syphilis, Chlamydia) increases the likelihood that sexual abuse is the cause. Perianal rashes should be cultured for sexually transmitted organisms if the history is suggestive or the rash is unresponsive to standard therapy. Full evaluation of perianal rashes is also important in order to avoid the erroneous diagnosis of sexual abuse. Perianal rashes mistakenly attributed to sexual abuse include those caused by molluscum contagiosum, pemphigus, lichen sclerosus et atrophicus, psoriasis, inflammatory bowel disease, perianal Streptococcus, anal stenosis, and diaper dermatitis.

INFECTIONS OF THE PERIANAL AREA

Many infections affecting the perianal area are discussed elsewhere in this text. Perianal streptococcal infection is common in infants and children. The rash is bright red, confluent, and usually confined to the direct perianal area (Fig. 416-2). Occasionally, the rash spreads to involve the entire perineum. Impetiginous vesicles and honey-colored crusting are often seen. The anal canal usually is involved. There is scant rectal bleeding on defecation and pain is often severe enough to produce dramatic fecal retention. Recent streptococcal infection in the family is common, and patients sometimes have simultaneous streptococcal pharyngitis. Culture of the anal canal is indicated in any infant whose red “diaper dermatitis” does not heal with standard therapy. Local antibiotics are ineffective. Oral penicillin is usually effective. In resistant culture-proven cases, clindamycin may be used.

Anogenital warts are usually caused by human papilloma virus types 6 and 11. Other serotypes, including type 2 (the usual cutaneous wart virus), may cause perianal disease. The relationship between this infection and sexual abuse is discussed previously. Chemical removal of perineal warts with topical podophyllin is difficult because isolation of the wart is not possible. Surgical removal of warts may be indicated if warts are extensive.7

FIGURE 416-2. Perianal streptococcal infection with typical intense erythema around the anus. (Reprinted with permission from Knoop KJ, Stack LB, Storrow AB. Atlas of Emergency Medicine, 3rd Edition. Copyright © The McGraw-Hill Companies, Inc., 2010. All rights reserved. Courtesy of Raymond C. Baker, MD.)

Molluscum contagiosum can affect the perianal area. The typical lesion is round, 2 to 3 mm in diameter, slightly raised, painless, gray-white, and umbilicated with a slightly erythematous base. Lesions usually are seen elsewhere on the body, and anal lesions most often result from autoinoculation. They may be transmitted by sexual contact. Cheesy squamous debris fills the lesions, and cytoplasmic inclusions can be seen in the expressed cells. Treatment is discussed in Chapter 367.

Candidal diaper dermatitis is the most common perianal infection in pediatrics. It is discussed in Chapter 367.

MALIGNANCY

Histiocytosis X can present as an eczematoid, perianal rash. Petechiae in the rash suggest this diagnosis; biopsy is necessary to confirm the diagnosis. Although rare in childhood, malignant melanoma may develop in the anal skin. Pigmented lesions in this area should be carefully observed and biopsied if they increase in size. Plexiform neurofibromas also arise in the skin of the perianal area. This lesion requires biopsy to confirm the diagnosis if no other signs of neurofibromatosis are present.