Rectal prolapse, a relatively uncommon clinical entity, is the prolapse of the rectal mucosa through the anus. In some instances, the rectal mucosa must be manually reduced if spontaneous reduction does not occur. Reduction can be easily performed by the pediatrician, emergency physician, or parent after adequate instruction. Although the procedure itself is not difficult, the presence of rectal prolapse in a young child should prompt the clinician to consider underlying causes for the condition.

Rectal prolapse begins with an internal prolapse of the upper rectum into the lower rectum. Further extension of the upper rectal mucosa through the anus creates a partial prolapse, the most common form seen in children. Continuation of this process results in a complete rectal prolapse (Fig. 90.1). Anatomic predisposing factors that may explain the predilection for rectal prolapse in certain children include vertical course of the rectum, flat sacrum and coccyx, and a lack of levator ani support (1).

Conditions that cause increased intra-abdominal pressure, hardening of the stool, or muscle weakness are also commonly associated with rectal prolapse (Table 90.1). Children under 3 years of age seem most susceptible to rectal prolapse, with the highest incidence found in children less than 1 year of age. The elderly comprise another high-risk group predisposed to rectal prolapse (2,3,4). Malnutrition most commonly causes rectal prolapse in underdeveloped countries, whereas in the United States most patients with rectal prolapse have stool abnormalities such as chronic constipation or diarrhea (1,2). Cystic fibrosis is the most serious of the potential etiologies for rectal prolapse in an otherwise well patient. Patients with cystic fibrosis have an 18% overall incidence of rectal prolapse (5). For this reason, children with noninfectious diarrhea and no other etiology for rectal prolapse or with recurrent idiopathic prolapse should be considered for a sweat chloride determination or other diagnostic tests for cystic fibrosis.

Children with rectal prolapse appear well. Rectal prolapse may even come to attention as an incidental finding by a clinician who notices a mass protruding from the anus. Often spontaneous reduction will occur before the patient is examined by medical personnel, and the clinician’s examination may only reveal laxity of rectal tone. In such cases, a presumptive diagnosis of rectal prolapse is made based on the description of the finding by the parents.

Any patient with a visible rectal prolapse should have it reduced. Before reduction, other conditions that can mimic rectal prolapse, such as rectal hemorrhoids, a prolapsed rectal polyp, and an ileocecal intussusception protruding through the anus, should be considered. Of these, intussusception requires emergent diagnosis and treatment. Differentiating features of intussusception include (a) a history of intermittent episodes of abdominal pain and crying, (b) ill appearance and in some cases obtundation (a later finding), and (c) the ability to pass a finger between the prolapsed bowel and the anal sphincter. Hemorrhoids and rectal polyps should be easily identified because they do not involve the entire rectal mucosa.