distal intestinal obstruction syndrome (DIOS)

Distal intestinal obstruction syndrome (DIOS) is one the of many abdominal manifestations of cystic fibrosis. In older children or young adults with cystic fibrosis, the distal small bowel may become obstructed with a mucofaeculent material in the distal ileum and right colon.

Epidemiology

DIOS occurs in 10-15% of patients with cystic fibrosis but the incidence is said to have decreased with the administration of microsphere pancreatic enzymes .

Precipitating factors include :

  • poor compliance with pancreatic enzyme
  • change of diet
  • dehydration

Prevalence is highest in the 2 and 3 decades of life

DIOS is said to be the most common gastrointestinal complication in cystic fibrosis patients following lung transplantation, especially if patients have had a diagnosis of meconium ileus in infancy .

Clinical presentation

Clinical manifestations of DIOS include :

  • abdominal pain: recurrent bouts of colicky abdominal pain
  • palpable cecal masses that may pass spontaneously
  • abdominal distention and flatulence are common

Clinical findings may mimic those of appendicitis or partial intestinal obstruction due to stricture or adhesions from previous bowel surgery.

Despite the common distension of the appendix by inspissated secretions, the reported prevalence of acute appendicitis in cystic fibrosis patients is lower than that in the general population.

Pathology

Pathologic mechanisms for this syndrome include inspissated intestinal secretions and pancreatic insufficiency, undigested food residue, disordered intestinal motility, fecal stasis and dehydration.

Radiographic features

Plain radiograph
Fluoroscopy
Water soluble contrast enema
  • may help to find the level of obstruction
  • aids in treatment/reduction of obstruction
CT
  • typically seen to affect the right colon
  • colonic wall thickening
  • mural striation
  • mesenteric soft-tissue infiltration
  • increased pericolonic fat
  • intussusception may be a complication
  • the appendix is routinely distended (>6 mm) in the absence of appendicitis resulting from mucoid impaction, and therefore the diagnosis of appendicitis should not be made unless secondary signs are present

Treatment and prognosis

Surgery is usually not required. Treatment options include:

  • water-soluble (e.g. Gastrografin) contrast enemas, result in an osmotic influx of water into the lumen of the bowel
  • intestinal lavage is reserved for recurrent but not complete obstruction, the aim is to wash out the accumulated secretions
  • colonoscopy is rarely necessary

Differential diagnosis

Small bowel obstruction from other causes including: