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The duodenum and small bowel are commonly abnormal in older children with CF. Thickened, nodular mucosal folds may be demonstrated on barium enema images (Figure 10). The precise cause is unknown. In the duodenum, the findings have been attributed to unbuffered gastric acid, which produces contraction of the muscularis, production of abnormal mucus, and Brunner gland hypertrophy (25,68). Mild, generalized small bowel dilatation with diffuse distortion and thickening of the mucosal folds, at times involving the entire colon and rectum, has also been described (68,69). In these cases, postevacuation images from a contrast material enema study may demonstrate a colonic mucosal relief pattern called "jejunalization," because the findings are reminiscent of the feathery, redundant mucosa seen in the normal jejunum on contrast agent examinations.
Duodenal ulcer caused by unbuffered gastric acid is uncommonly diagnosed, although it is seen at autopsy in 10% of children with CF (25). However, the true antemortem prevalence of peptic ulcer disease may be underestimated, since the radiologic findings may be masked by concurrent mucosal abnormalities (70). Thus, peptic ulcer disease should be a diagnostic consideration in a CF patient with hematemesis, in addition to bleeding varices from portal hypertension.
Pneumatosis intestinalis is more commonly associated with CF than was once believed. In a review of autopsy records for a 40-year period (1944-1984), Hernanz-Schulman and coworkers (71) identified pneumatosis intestinalis in 21 (4.8%) of 441 patients with CF. Pathologically, pneumatosis intestinalis was confined to the colon and tended to be submucosal and cystic when one-half or less of the colon was involved. Both submucosal and subserosal blebs were found when colonic involvement was more extensive, and the mural cysts tended to be accompanied by linear gas collections in the bowel wall (Figure 11). Pneumatosis intestinalis correlated with the development of obstructive pulmonary disease and air leakage into the pulmonary interstitium. The data supported the theory that pneumatosis intestinalis results from the infradiaphragmatic dissection of air along perivascular connective tissue planes. The authors postulated that a steady state develops in the setting of chronic air block phenomena, with new linear and cystic collections of mural air constantly replacing those that resolve by resorption and fibrosis. In the absence of pneumothorax, this self-perpetuating process may be clinically silent.
Gastroesophageal reflux is a recently recognized manifestation of CF (72,73,74). In one study, gastrointestinal symptoms suggestive of gastroesophageal reflux were found in 26.5% of CF patients younger than 5 years (75). However, esophageal pH probe studies suggest a much higher prevalence (76,77). It has been suggested that diaphragm depression due to pulmonary hyperinflation, increased abdominal pressure associated with cough, and increased volume of swallowed secretions contribute to gastroesophageal reflux in these children (73,78). Moreover, medications such as theophylline and a-adrenergic agents may reduce lower esophageal pressure and promote gastroesophageal reflux (72).
Gastroesophageal reflux represents a significant additional cause of morbidity in patients with CF. Well-known complications of gastroesophageal reflux include anemia, esophagitis, and peptic esophageal stricture (75,78,79,80). Most recently, Barrett esophagus, a premalignant condition, has been described in two adolescent patients with CF (77). Barrett esophagus was considered present when the normal squamous mucosa had undergone metaplastic change to specialized columnar epithelium, with goblet cells containing acid mucin positive with Alcian blue stain at pH 2.5. The authors concluded that Barrett esophagus was evidence of exceptionally severe gastroesophageal reflux, which may compound preexisting pulmonary and nutritional problems in CF patients. Upper endoscopy and multiple biopsies were recommended for any child with CF and symptoms of gastroesophageal reflux. Barrett-specialized metaplasia is known to take years to develop in the face of chronic severe gastroesophageal reflux. Thus, surveillance for Barrett esophagus may assume increasing importance with the increasing life span of CF patients. In children, only antireflux surgery has been shown to cause regression of Barrett esophagus (81).
Rectal mucosal prolapse is found in approximately 20% of patients with CF, is most frequent in children under the age of 3 years, and may be the presenting sign that suggests the diagnosis (19,72). Contributing factors include frequent bulky stools, diminished muscle tone, and increased intraabdominal pressure from pulmonary hyperinflation and coughing. The diagnosis is made clinically. Treatment consists of manual reduction and institution of exocrine pancreatic enzyme replacement once the diagnosis of CF is established. Surgery is rarely required.
Nonobstructive Bowel Manifestations