Short Bowel Syndrome

Alternative names: Short Gut Syndrome, Short Gut.

Short bowel syndrome is a malabsorption disorder in which part(s) of the small intestine are missing either due to surgery, a congenital defect, or dysfunction of a large segment of bowel.  In general, at least one-half to two-thirds of the small intestine needs to be missing before the effects become obvious.

The normal adult small intestine is approximately 6 meters (20 feet) in length.  Short bowel syndrome usually develops when the length of functional small intestine is under 2 meters (about 7 feet.)

Causes and Development

The types of surgery that can cause short bowel syndrome include surgery for:

• Crohn's disease
• Volvulus (abnormal twisting of a portion of the gastrointestinal tract that cuts off the blood supply and leads gangrene and tissue death in the affected segment)
• Tumors of the small intestine
• Repairing injury of, or trauma to, the small intestine
• Necrotizing enterocolitis (in premature newborns)
• Treating obesity (intestinal bypass surgery)
• Removing a diseased or damaged portion of the small intestine.

Treatment and Prevention

In cases of mild short bowel syndrome, eating small, frequent meals; increased fluid intake; nutritional supplements; and using medications to treat diarrhea may be all that is needed.

In moderate to severe cases, a high-calorie diet including concentrated essential vitamins and minerals, carbohydrates, proteins, and fats, will go a long way towards compensating for the lack of nutrient absorption.  Some vitamins and minerals may still need to be given by injection, and in serious cases intravenous feeding end electrolyte supplements may also be required until the situation improves.

If anemia is present, this needs to be treated (with vitamin B-12, folic acid, and increased supplemental/dietary iron.)

Medications to slow intestinal motility increase the time available to absorb nutrients.

Prognosis; Complications

There may be a gradual improvement in nutrient absorption over time if short bowel syndrome has occurred as a result of surgery.  This improvement is due to the fact that the small intestine is able to adapt to some extent; changes to the remaining portion of small intestine occur naturally and increase its absorptive capacity.  The changes include enlargement and lengthening of the villi found in the lining, increase in diameter of the intestine, and slowed movement of food through the small intestine.

The long-term outlook depends on what section(s) of the small intestine were removed, how much remains, and how well the remaining small intestine can adapt.  Intestinal adaptation can take up to 2 years to occur.

The main adverse consequence of short bowel syndrome is that there may not be enough surface area left in the remaining intestine to absorb enough nutrients from food.

Other complications include:

• Small Intestine Bacterial Overgrowth (SIBO)
• Vitamin B12 deficiency symptoms such as nervous system problems
• Metabolic acidosis due to diarrhea
• Gallstones
• Kidney stones
• Malnutrition
• Weakened bones (osteomalacia)
• Weight loss