There are three types of rectal prolapse:
- Complete: full thickness of rectum prolapses through anus (two layers of rectum with an intervening peritoneal sac, which may contain small bowel)
- Incomplete/mucosal: prolapse limited to only two layers of mucosa
- Concealed: internal intussusception of upper rectum into lower, with no extrusion into the anus
- Most cases occur in children <4 years of age around time of toilet training; 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
- Cystic fibrosis (CF)
- Typically presents between 6 months and 3 years of age in patients with CF
- Presentation in children with CF >5 years of age is rare.
- Chronic constipation
- About 50% of children with chronic constipation will experience prolapse.
- Inheritance patterns depend on associated underlying etiologies.
- No known inheritance pattern for idiopathic rectal prolapse
Exact etiology uncertain
Commonly Associated Conditions
- Excessive straining with bowel movements from constipation and toilet training (hips and knees flexed) is the most common cause in industrialized countries.
- Diarrhea; may be more of a cause in tropical and subtropical countries
- Infections: hookworms and other parasitic infections
- Malnutrition; can cause loss of the ischiorectal fat pad
- Complication of past surgery, such as imperforate anus repair
- Complete prolapse is rare in children, but when it occurs, it may be related to poor fixation of rectum to sacrum and to weak pelvic and anal musculature.
- Ulcerative colitis
- Hirschsprung disease
- Ehlers-Danlos syndrome
- Rectal polyp
- Rectal neoplasm
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