Distal intestinal obstruction syndrome is most common in older adolescents with a prevalence of 10% to 15.8%.13 The greatest risk factor is prior DIOS. In constipation, stool and gas accumulate gradually in the colon with or without colonic dilatation. Nonstimulant laxatives (ie, polyethylene glycol) are most commonly used for treatment of constipation and prevention of DIOS. Patients may require admission for nasogastric administration of the large volumes that are often needed (20-40 mL/kg/h) until effluent is clear. A gastrografin enema can be performed by a radiologist for treatment of DIOS.
If DIOS is refractory to standard treatments, alternate diagnoses should be considered, such as intermittent intussusception, ileal Crohn disease, or appendicitis. In CF, appendicitis mimics DIOS due to its atypical presentation with classic symptoms frequently absent. Interestingly, appendicitis occurs in 1% to 2% of children with CF compared with 7% of the non-CF population, likely because of the frequent use of antibiotics in CF. However, due to confusion with DIOS, perforation is more common.12
Sixty-seven percent of children with CF have reflux on impedance monitoring. Reflux is attributed to a variety of factors, including delayed gastric emptying; impaired gut motility; increased intra-abdominal pressure from coughing; effects of respiratory medications on the lower esophageal sphincter (LES) pressure; inherently decreased LES basal tone; hyperinflation of lungs with increased transdiaphragmatic pressure; abnormal esophageal peristalsis; postural drainage techniques in infants; and a high fat diet.14 Acid reducers increase the pH of refluxate but may not necessarily affect frequency of episodes of reflux unless the reflux is so severe that acid exposure has impaired the LES. Acid reducers should not be used indefinitely as they have been associated with small intestinal bacterial overgrowth and an increased risk of respiratory infections.
Altered motility also results in duodenogastroesophageal reflux, as demonstrated by increased bile in the stomachs of children with CF.14 Bile salts are an irritant and airway exposure correlates with worse lung disease. Erythromycin, which improves gastric emptying on scintinography in patients with CF, may offer benefit.
MICROBIOME CHANGES: SMALL INTESTINAL BACTERIAL OVERGROWTH (SIBO), CLOSTRIDIUM DIFFICILE
Small intestinal bacterial overgrowth (SIBO) can present with abdominal pain, bloating, and diarrhea as well as nutrient malabsorption.10 Providers should have a high index of suspicion for this diagnosis and treat empirically as the breath tests used in other populations are difficult to interpret in CF. Diagnosis should be under the guidance of a gastroenterologist.
Patients with CF have risk factors for acquisition of Clostridium difficile infections, including recurrent antibiotics use, hospitalization, dysbiosis, and acid reducer use. Asymptomatic carriage rates in CF are 22% to 55%.12 Diarrhea is uncommon. The presentation is often fulminant disease with rapid progression to toxic megacolon.
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