Chapter 62: Anal and Rectal Disorders

It is important to recognize the various anal and rectal disorders in infants and children. In this chapter, the following disorders are discussed in succession:

1. Hirschprung disease

2. Imperforate anus

3. Rectal prolapse

4. Anal fissure

5. Anal abscess and Fistula in ano

Hirschsprung Disease

Patient Story

An 8-week-old girl is brought to your office with abdominal distention and constipation. On digital examination of her anus she has an episode of explosive diarrhea and flatus. A plain radiograph shows stool impaction and a contrast enema reveals a transition zone in the sigmoid colon (Figure 62-1). A suction biopsy confirms the diagnosis of Hirschsprung disease. An enema regimen was started and 3 weeks later she underwent a primary pull through operation.

Introduction

Hirschsprung disease is a developmental disorder of the enteric nervous system characterized by absence of ganglion nerve cells in the myenteric and submucosal plexuses of the distal intestine.

Synonyms

Hirschsprung disease; partial or total aganglionosis; congenital megacolon.

Epidemiology

• US: 1 case per 5400 to 7200 newborns.

• Worldwide: 1 case per 1500 to 7000 newborns.¹

• Most cases are diagnosed by 2 years of age.

Etiology and Pathophysiology

• Congenital aganglionosis of the distal bowel leads to impaired bowel peristalsis with constipation. The aganglionosis usually begins in the anus and continues proximally for a variable distance.

• There are two theories for the aganglionosis: The incomplete migration of ganglion cells from the neural crest to the distal bowel or the dysfunctional maturation or apoptosis of primitive nerve cells. There is increasing evidence that mutations in a variety of genes, including the RET proto-oncogene, may play a key role in the etiology.^2,3

Risk Factors

• Race: No racial predilection.

• Sex: Male to Female ratio 4:1.

• About 10 percent of patients have a positive family history.

• Trisomy 21.

Diagnosis

History

• Neonatal period.

  • Consider the diagnosis in any newborn with delayed passage of first meconium. beyond the first 24 hours, abdominal distention, and repeated vomiting.

  • Signs of intestinal obstruction with bilious vomiting, poor feeding, and failure to thrive.

• Children.

  • Chronic constipation, abdominal distension since birth.

  • Soiling and overflow incontinence.

• Enterocolitis.

  • Ten percent of all patients present with fever, abdominal distension, and diarrhea caused by enterocolitis, which can progress to colonic perforation and life-threatening sepsis.

Clinical Features

• Physical examination may reveal a distended abdomen and/or a hypertonic anus with empty rectum.

• Digital rectal examination ...