What is the pathophysiology of pediatric rectal prolapse?

Updated: Nov 12, 2018
  • Author: Jaime Shalkow, MD, FACS; Chief Editor: Carmen Cuffari, MD  more...
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A pelvic floor defect with levator ani muscle diastasis and a deep endopelvic fascia represent the pathophysiologic of the disease. Patients with rectal prolapse have lost the normal semihorizontal rectal position; they also have weak muscle insertions to the pelvic walls and sacrum, and an abnormally deep Douglas pouch. A redundant rectosigmoid and weaker / wider anal sphincter are common.

The normal resting tone of the anal sphincter decreases in response to rectal distention. In 1962, Porter found that patients with rectal prolapse have a profound and lengthy response and weakened tone of the levator ani muscles. [4] Whether this is a causative factor or a secondary finding is not clear, since the prolapse begins above the pelvic musculature.

Rectal prolapse has been associated with a myriad of conditions, including:

  • Increased intra-abdominal pressure due to straining (as often occurs in toilet training and constipation)
  • Parasitic disease (the most common cause of rectal prolapse in developing countries)
  • Neoplastic disease
  • Malnutrition (loss of ischiorectal fat pad) - Worldwide, this is possibly the most common condition associated with pediatric rectal prolapse; the loss of ischiorectal fat reduces perirectal support
  • Meningomyelocele
  • Surgical repair of anorectal malformation
  • Fecal incontinence and diarrhea [5, 6]
  • Chronic constipation [7]
  • Neuromuscular disorders
  • Mental challenge [8]
  • Poor sacral root innervation (Spina bifida)
  • Bladder or cloacal exstrophy [9]
  • Scleroderma [10]
  • Hirschsprung disease (especially in ultrashort aganglionic segment, which acts as subocclusion, favoring prolapse) [11]
  • Rectal polyps (the polyp acts as a leading point) [12]
  • Shigellosis in neonates [14]

Cystic fibrosis deserves special attention as cystic fibrosis may cause rectal prolapse in children. In the past, rectal prolapse was described in up to 20% of individuals with cystic fibrosis. However, current reports estimate an incidence of 3% of children with the disease. [15, 16] Potential mechanisms include bulky bowel movements, coughing paroxysms, and undernutrition. It is most frequently seen in toddlers, but it can occur at any age (triggered by cough)

Clinical clues to cystic fibrosis include oily, malodorous, or floating stools; poor growth; wheezing or other respiratory symptoms; and digital clubbing. The absence of respiratory symptoms and normal findings upon physical examination do not necessarily exclude this diagnostic possibility. Sweat chloride and genetic testing confirm the diagnosis.

Most cases of childhood rectal prolapse occur in children younger than 4 years, with the highest incidence during the first year of life. Anatomic considerations related to this early presentation include the vertical course of the rectum along the straight surface of the sacrum, a relatively low position of the rectum in relation to other pelvic organs, increased mobility of the sigmoid colon, relative lack of support by the levator ani muscle, loose attachment of the rectal mucosa to the underlying muscularis, and absence of Houston valves, seen in about 75% of infants.

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