Distal Intestinal Obstruction Syndrome (DIOS) is a specific type of bowel obstruction. This condition involves the accumulation of thickened, sticky contents within the digestive tract, leading to impaired passage of stool. While similar to general constipation, DIOS is a more serious obstruction that typically requires medical attention.
What is Distal Intestinal Obstruction Syndrome
Distal Intestinal Obstruction Syndrome occurs when the contents of the intestine, primarily in the distal ileum (the final part of the small intestine) and the colon (large intestine), become abnormally thick and sticky, forming a mass that causes a partial or complete blockage. This mechanism involves a combination of dehydrated intestinal secretions and undigested food residues.
This condition differs from other types of bowel obstructions because of its specific cause: the abnormal consistency of intestinal contents rather than a physical narrowing or twisting of the bowel itself. While other obstructions might involve scar tissue, hernias, or intussusception, DIOS is distinct in its pathophysiology, stemming from the inability to properly hydrate and move intestinal material. It was previously known as meconium ileus equivalent, a bowel obstruction seen in newborns with cystic fibrosis.
Who is Affected and Why
DIOS primarily affects individuals with cystic fibrosis (CF), occurring in 15% to 20% of people with CF. The connection between CF and DIOS stems from the fundamental defect in the cystic fibrosis transmembrane conductance regulator (CFTR) protein, which is responsible for regulating salt and water transport in various organs, including the intestines. This protein dysfunction leads to the production of abnormally thick and sticky mucus throughout the body, including the digestive tract.
In people with CF, pancreatic insufficiency is a common complication where the pancreas does not produce enough digestive enzymes. This leads to malabsorption of fats and other nutrients, contributing to the formation of viscous, undigested material in the intestines. Other factors contributing to DIOS include dehydration, which further thickens intestinal contents, and inconsistent adherence to pancreatic enzyme replacement therapy. Changes in diet or routine, such as illness, decreased physical activity, or even environmental shifts, can also predispose individuals to DIOS by slowing bowel function or reducing fluid intake.
Recognizing and Diagnosing DIOS
Symptoms of DIOS commonly include sudden onset of crampy abdominal pain, often located in the center or lower right abdomen. Individuals may also experience abdominal distension (bloating), nausea, and vomiting, sometimes with green or yellow bile. A reduction in stool passage or harder stools is notable, and a palpable, firm mass may be felt in the right lower abdomen.
Diagnosis typically involves a physical examination and imaging studies. During a physical exam, a healthcare provider may feel for an abdominal mass. Abdominal X-rays are frequently used to confirm obstruction, revealing impacted stool in the end of the small intestine and beginning of the large intestine, or dilated loops of the small intestine with air-fluid levels. In complex or less clear cases, a computed tomography (CT) scan or ultrasound may be performed to visualize dilated loops of intestine filled with thick material and gas bubbles, aiding in a definitive diagnosis.
Treatment and Management
The primary goal of DIOS treatment is to clear the intestinal blockage and prevent surgery. Medical management typically begins with rehydration, increasing oral fluid intake or administering intravenous (IV) fluids if the individual is unable to drink sufficiently. Osmotic laxatives, such as polyethylene glycol solutions (e.g., Movicol or Golytely), are commonly used. They work by drawing water into the intestines, softening the impacted stool and promoting its passage.
In more severe cases, or when oral laxatives are insufficient, intestinal lavage solutions like Gastrografin may be administered orally or via a nasogastric tube to dislodge the obstruction. These solutions are potent osmotic agents that draw substantial fluid into the bowel. Surgery is generally reserved for situations where medical treatments fail or if complications such as peritonitis arise. Surgical procedures can include disimpaction with washout, or in rare cases, removal of a portion of the intestine.
Preventing DIOS
Preventing DIOS involves consistent adherence to a regimen designed to maintain healthy bowel function, especially for susceptible individuals. Adequate hydration is a primary preventative measure; drinking sufficient fluids, particularly water and salt-replacement drinks during physical activity or in warmer climates, helps keep intestinal contents soft. Consistent adherence to pancreatic enzyme replacement therapy is also important, as these enzymes aid in the proper digestion of food and prevent the formation of thick, undigested material.
Regular bowel habits should be encouraged, and delaying bowel movements avoided. Incorporating a diet rich in fruits, vegetables, and high-fiber breads and cereals can also support regular bowel function. Some individuals may benefit from regular use of stool-softening medications, such as lactulose, as prescribed, to prevent stool impaction.