DESCRIPTION

Defined as a protrusion of tissue through the anal verge; there are three types of rectal prolapse:

• Complete: full thickness of rectum prolapses through the anal verge (two layers of rectum with an intervening peritoneal sac, may contain intraabdominal contents)
• Mucosal: prolapse limited to inner layer of the rectum only—the mucosa
• “Hidden”: rectorectal or ileocolonic intussusception, with no extrusion through the anal verge

EPIDEMIOLOGY

• Commonly in children <4 years of age around time of toilet training
• Highest incidence in 1st year of life
• Equal incidence in boys and girls
• In older children and adults, strong (6-fold) female predilection
• Common in developing countries, perhaps because of poor nutrition and parasitic infection; less common in industrialized countries

ETIOLOGY

Rectal prolapse should be approached as a symptom of an underlying condition rather than a discrete disease entity, as to not miss primary problems that may present as rectal prolapse.

• Increased incidence in early childhood is thought to relate to several important anatomical considerations:
  • More vertical course of the rectum
  • Flatter coccyx
  • Relatively weak levator support and relatively low position of rectum in the pelvis
  • Increased mobility of the sigmoid colon
  • Loose attachment of the redundant rectal mucosa to the underlying muscularis
  • Absence of Houston valves in about 75% of infants <1 year of age
• This is in contrast to the incidence of rectal prolapse in older adults typically due to pelvic muscular weakness.

RISK FACTORS

• Constipation
• Cystic fibrosis (CF)
  • Less common now that CF is included in newborn screening
  • Typically presents between 6 months and 3 years of age in patients with CF
  • Incidence up to 23% in patients with CF
  • Presentation in children with CF >5 years of age is rare.
• Solitary ulcer of the rectum syndrome (SURS)
• Inflammatory cloacogenic polyps (ICP)

COMMONLY ASSOCIATED CONDITIONS

Many unrelated conditions predispose to rectal prolapse and can be grouped into several broad categories:

• Increased intraabdominal pressure
  • Excessive straining with bowel movements from constipation and toilet training (hips and knees flexed) is the most common cause in industrialized nations.
  • Pertussis
  • Chronic lung disease and coughing
  • Chronic straining during urination (phimosis)
• Acute or chronic diarrheal illnesses
  • Infectious (Escherichia coli O157:H7, hemolytic uremic syndrome [HUS], giardiasis, etc.)
  • Malabsorptive (celiac disease, pancreatic insufficiency)
• Parasitic and neoplastic diseases
• Malnutrition: most common worldwide
  • Leads to loss of ischiorectal fat
• CF
  • In the era of newborn screening for CF, lower incidence is reported (3.5%).
  • Previously reported in up to 20% of CF patients
  • May be a presenting symptom of CF preceding more common characteristics such as pulmonary disease or malabsorptive diarrhea
• Pelvic floor weakness
  • Neurologic disorder
  • Myelomeningocele
  • History of anorectal malformations
• Miscellaneous
  • Ehlers-Danlos syndrome
  • Hypothyroidism
  • Hirschsprung disease
  • Ulcerative colitis
  • Laxative abuse