JAOCR at the Viewbox: Distal Intestinal Obstruction Syndrome (DIOS)

Distal Intestinal Obstruction Syndrome (DIOS)

A 35-year-old man presented to the emergency department with acute abdominal pain and he underwent intravenous contrast-enhanced CT of the abdomen and pelvis. Coronal CT image (Figure A) demonstrated an abrupt caliber transition (arrow) with dilated proximal small bowel containing bubbly fecalized material. Axial CT image (Figure B) at the level of the pancreas revealed complete fatty replacement and enlargment of the pancreas (arrow).

Cystic fibrosis is a relatively common inherited disease affecting multiple organ systems with increased thickness of mucous/secretions. The lungs, pancreas, and gastrointestinal (GI) tract are more commonly affected.^1,2 As treatments of pulmonary manifestations continually improve, familiarity with extrapulmonary adult manifestations is gaining importance with imagers.^1,2 A wide array of GI tract pathology has been described in cystic fibrosis patients including gastroesophageal reflux, DIOS, and constipation.²

In the cystic fibrosis patient population, DIOS occurs in up to 15% of the these patients.¹ It is characterized by the buildup of a mixture of viscous mucous and feculent material within the terminal ileum and/or right colon, leading to a bowel obstruction.^1,2 In cystic fibrosis patients, DIOS has been shown to more commonly occur in patients with pancreatic insufficiency, prior DIOS, a history of a meconium ileus episode, and dehydration.^1,2 Fatty replacement of the pancreas, as demonstrated in this case, is also commonly seen in cystic fibrosis and, although not specific, can be a tip-off to the interpreting radiologist to the presence of the disease.¹

Imaging findings in DIOS include the findings of a small bowel obstruction including dilated loops of bowel proximal to the obstruction. At the transition point, there is a mass-like intraluminal soft-tissue density (representing the viscous secretions and fecal material) with internal gas bubbles. The images should also be critiqued for complications regarding the bowel obstruction, including perforation. Water-soluble contrast enema may be both diagnostic and therapeutic. Other treatment options include rehydration and stool softeners, with surgery reserved for complicated cases and/or cases that fail conservative treatment.¹

References

1. Lavelle LP, McEvoy SH, Mhurchu EN, et al. Cystic fibrosis below the diaphragm: abdominal findings in adult patients. RadioGraphics 2015;35(3):680-695.
2. Morton J, Ansari N, Glanville A, Meagher AP, Lord RVN. Distal intestinal obstruction syndrome (DIOS) in patients with cystic fibrosis after lung transplantation. J Gastrointest Surg 2009;13:1448-1453.