Rectal prolapse (RP) is a circumferential, full-thickness protrusion of the rectal wall through the anal orifice (1). Although the exact incidence of RP has not been determined, it is common and self-limited in children younger than 5 years, with almost equal sex incidence (2,3). Various anatomical variants and medical conditions including cystic fibrosis (CF) predispose a child to developing RP (4).
An early review of CF revealed that 23% of patients with CF experienced RP and that 78% of these patients experienced RP before diagnosis of CF. This led to the recommendation that CF should be considered in a child with RP of unknown etiology (5). Stern et al (6) revisited this recommendation in 1982, showing that RP preceded the diagnosis of CF in 43% of these patients. RP led directly to the diagnosis of CF in approximately 20% of patients; after CF diagnosis, RP resolved with pancreatic enzyme replacement therapy (PERT) in 72% of patients. This led them to recommend that unexplained RP should undergo sweat chloride testing for CF. Most children with prolapse, however, do not have undiagnosed CF, particularly in the absence of other symptoms (6,7).
Newborn screening (NBS) for CF has been the standard of care in Wisconsin since 1994 (8) following the development of a radioimmunoassay for immunoreactive trypsinogen (IRT) (9). Sweat chloride testing is routinely performed on children with positive NBS to confirm the diagnosis of CF so that treatment may be initiated as early as possible to prevent lung and nutritional complications of CF.
In the era of CF NBS, we were interested in evaluating the necessity of sweat chloride testing in patients with RP. Specifically, we hypothesized that children presenting with RP and without any symptoms or signs of CF do not have CF. Our aims were to study the frequency of positive sweat chloride tests in patients with RP, describe the frequency of RP in patients with CF, and identify factors that may be associated with RP in patients with CF.
This retrospective study of children who presented to the Children's Hospital of Wisconsin (CHW) with RP between 2000 and 2010 was approved by CHW's institutional review board. Information collected included anthropometrics, diagnosis location (gastroenterology clinic, surgery clinic, emergency room, inpatient admission, laboratory visit), medical history, and workup (sweat chloride test). For patients with CF, additional information collected included age of CF diagnosis, genetic mutation, pancreatic function status, and dosage of pancreatic enzymes. Pancreatic function status was defined by genetic testing (children who were homozygous for delta F508 mutations were presumed to be pancreatic insufficient); otherwise, they underwent annual stool elastase testing. These patients would have ideally undergone the NBS for CF using the 2-tiered immunoreactive trypsinogen (IRT)/DNA technique. Microsoft Excel (Microsoft, Redmond, WA) was used for the data analysis.
To identify factors that may be associated with RP in patients with CF, we identified 3 age-matched controls (the children with CF at our institution who were closest in date of birth to each patient). We then compared them with respect to sex, CF genotype, pancreatic sufficiency/insufficiency, and whether or not they were diagnosed by NBS. We also compared them with respect to constipation, diarrhea, adequacy of pancreatic enzymes, distal intestinal obstruction syndrome, and hospital admissions for respiratory exacerbations in the year prior to when the patients experienced RP. Finally, we compared their body mass index or weight-for-length and percent-predicted forced expiratory volume in 1 second as close as possible to the time that the patients experienced RP. Fisher exact test was used to conduct these comparisons.
We identified 262 patients with RP; 65% were boys. The mean age of presentation with RP was 4 years 8 months (range 1 month to 18 years). Most patients with RP were diagnosed in the gastroenterology clinic (34%). Of these 262 patients, retrospective review of medical records identified a diagnosis in 194 patients. The most common associated diagnosis was constipation (52.1%), followed by acute diarrhea (12%), imperforate anus (8%), rectal polyps (6%), and meningomyelocele (5%), whereas 3.6% of patients had CF based on the NBS or sweat chloride testing; the remaining 13.4% of patients had Hirschsprung disease, proctitis, rectal ulcer, recurrent chest infections, malnutrition, rectal neoplasms, anorectal anomalies, and ulcerative colitis. Sweat chloride test was performed in 81 patients with RP with unknown CF status; 2 were diagnosed as having CF based on that sweat chloride test. Five patients with CF presented with RP after being diagnosed as having CF based on NBS.
Incomplete anthropometric data included missing heights/lengths in 106 patients, missing weights in 47 patients, and missing heights/lengths and weights in 4 patients. Of the patients who underwent sweat chloride testing, 4 were malnourished (3 having a body mass index z score <−1.89, and 1 having a weight-for-height z score <−1.89). None of the patients eventually diagnosed as having CF were malnourished.
In our center, 120 patients were born and diagnosed as having CF, including CF-related metabolic syndrome, between 2000 and 2010. Of these, 19 patients were not diagnosed by the NBS; 12 of these 19 patients were born outside of Wisconsin. Table 1 summarizes the data for the patients with CF with RP. These patients represent 3.5% of our center's patients with CF. The 2 patients whose RP led to their diagnosis of CF had a history of multiple upper respiratory infections as well as needing medical and surgical management of sinus infections.
No demographic or clinical factors were associated with RP in patients with CF (Table 2). No patients in either group experienced distal intestinal obstruction syndrome. Because only 2 patients with RP and CF were older than 6 years, we were unable to obtain valid forced expiratory volume in 1 second measurements on the other patients and did not study this further.
Our 10-year review of patients with RP revealed that 3.6% of patients had CF, and conversely, 3.5% of our center's patients with CF had RP. This is less than the frequency observed several decades ago, and may be owing to earlier diagnosis of CF through NBS, and hence earlier optimal management of CF. NBS for CF has been associated with improved nutritional outcomes (10–12), and this may also contribute to the lower incidence of RP. In our study, since the onset of NBS, patients with CF—both with and without RP—have had fewer complications associated with malabsorption, constipation, and diarrhea.
In our study, the most common association with RP was constipation. Straining with constipation forces the anterior wall of the upper rectum into the anal canal, and with time, the rectal attachments to the sacrum become loose so that a circumferential prolapse occurs (13).
Two of the 7 patients with CF were diagnosed as having CF after sweat chloride testing was ordered because of their RP; however, their medical history, pertinent for multiple upper respiratory tract and sinus infections, suggested CF. Five patients were diagnosed by NBS; of these, 4 were pancreatic insufficient, and despite early intervention with enzymes, still developed RP. These cases support the importance of factors other than pancreatic insufficiency as a cause of RP, such as increased intra-abdominal pressure secondary to coughing or constipation. Our review has shown that in patients without CF, RP is most likely secondary to constipation, and in patients with CF, this may explain why pancreatic enzyme supplementation alone does not necessarily help resolve all cases of RP. Malnutrition and failure to thrive, the hallmarks of CF, may be noted in these patients with RP owing to CF.
Limitations of this study include those inherent with retrospective reviews. Despite online charting, data may be incomplete, as with missing anthropometrics, especially with older charts or in certain visits (emergency room, laboratory). It is assumed that anthropometrics were obtained in the standard manner. Clinic notes were not standardized in terms of history components. Patient follow-up regarding RP recurrences as well as sweat chloride testing at different centers was difficult to obtain. In addition, although we were able to obtain a history of repeated upper respiratory infections in children who were ultimately diagnosed as having CF, this type of history could not be ruled out in the vast majority of our patients. The major limitation of our study was that all of the patients with RP did not have sweat testing done; however, sweat testing is available in only 5 accredited CF centers in Wisconsin. Moreover, it is unlikely that a large number of children with CF were missed by our study because NBS in Wisconsin has had a clinical sensitivity of 94% to 95% since 1994 (14). Our attempts at uncovering clinical factors that we found were not associated with RP in CF have the limitations of a retrospective review. We were unable to use standardized definitions for constipation and diarrhea, and we were also unable to confirm the adequacy of PERT by fecal fat testing.
RP is an uncommon presenting symptom with less than 30 children per year being seen at our children's hospital for this complaint. In addition, our data suggest that CF would be unusual in the individual child with RP but it is important not to miss the diagnosis of CF in any child. Because NBS does have false negatives, rarely children with RP may have an underlying diagnosis of CF. Although both children had other symptoms that are seen with CF, these were not considered until the RP occurred. We believe that physicians should continue to obtain sweat tests in all of the children with RP with the understanding that it is a test with a low yield in the era of NBS.
The authors thank Mary Ellen Freeman, APNP, Pediatric Pulmonology, CHW, and Evans Machogu, MD, Pediatric Pulmonology, CHW, for their assistance with information regarding patients with CF for this study.
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