Distal Intestinal Obstruction Syndrome (DIOS)

Fig.1: Axial CT without IV contrast shows absence of pancreas (star), which is a feature of cystic fibrosis. The colon (arrow) is filled with fecal materials.
Fig.2: CT image at the lower cut reveals 'fecalization' of small bowel, and collapsed descending colon. This patient has known cystic fibrosis status post recent lung transplantation. He developed intermittent abdominal distension and diarrhea. He did not have peritoneal irritation sign on physical exam.

Facts

• DIOS is short for 'distal intestinal obstruction syndrome'. Also known as meconium ileus equivalent (MIE)
  
• Unique to cystic fibrosis (CF)
  
• 10% - 15% of patients with CF
  
• Caused by accumulation of mucous and feces in small bowel and ascending colon
• Common in older child or young adult
• Predisposing factors: after transplantation (probably due to dehydration and medications), dehydration, pancreatic enzyme supplement cessation, unknown
  

Radiographic Features

• Fecal materials in terminal ileum, cecum and ascending colon
• Thickened mucosal fold of bowel
  

Reference:
1. Moody AR, et al. CT monitoring of therapy for meconium ileus. J Comput Assist Tomogr 1990 (November/December)
2. Agrons GA, et al. Gastrointestinal manifestations of cystic fibrosis: radiologic-pathologic correlation. Radiographics 1996 (July)