The small intestine is an important part of the digestive system because it is the site where most of the nutrients are absorbed from the food we eat. When problems arise in the small intestine, the ability to absorb those nutrients can become compromised, and our overall health can begin to suffer. One rare but serious condition that primarily affects the small intestine is called short bowel syndrome. Short bowel syndrome is the group of symptoms and complications that result from the malabsorption of nutrients.
What Does the Small Intestine Do?
The small intestine is just one part of the larger gastrointestinal tract, the passageway from the mouth to the anus that processes the food we eat and turns it into useful material for our cells. Every time we eat, the chewed food travels down the esophagus and into the stomach where it is exposed to stomach acid and digestive enzymes; additionally, a series of muscle contractions called peristalsis mashes up the food into a substance that is partially solid and partially liquid. The stomach’s main purpose is to prepare the chyme for passage into the small intestine; very few nutrients are actually absorbed by the body up to this point.
From the stomach, the chyme passes into the duodenum, the first part of the small intestine. The duodenum is where gastric juices from the pancreas and liver are released into the digestive tract in order to further break down the chyme; the duodenum is also where bicarbonate from the pancreas neutralizes stomach acid. The midsection of the small intestine is the jejunum, where sugars, fatty acids, and amino acids from chyme are absorbed into the bloodstream. The final section of the small intestine is the ileum, and its role is to absorb vitamin B12 and other nutrients as well as reabsorb bile salts that originated in the liver.
What is Short Bowel Syndrome?
Short bowel syndrome (SBS) is the term for the group of symptoms that may develop if the small intestine is unable to function properly and absorb nutrients that the body needs. The lack of proper function stems from the small intestine essentially being too short; while there are rare cases of people being born with shortened small intestines, it is most commonly the result of damage to the intestine or the surgical removal of a portion of the small intestine. Short bowel syndrome is fairly rare, and only about 3 new cases per million people are diagnosed each year in the United States.
The length of the small intestine can vary greatly from person to person, but the average length is around 20 feet. Small bowel syndrome tends to develop only when a significant portion of this length is damaged or removed during surgery—it usually requires more than half of the intestine to be removed or nonfunctional. The basic reason the symptoms begin is because there isn’t enough length to absorb sufficient nutrients. This is because the normal digestive process uses the entire length to gradually break down chyme into individual compounds that can actually be absorbed into the bloodstream and used by our cells.
Symptoms of Short Bowel Syndrome
The primary symptom of short bowel syndrome is diarrhea, the passing of loose or watery stools. Though the large intestine is generally responsible for the absorption of water from stool, it is the overall disruption to the digestive process that increases bowel motility and results in diarrhea. In addition to being the most common symptom, it is also one of the most dangerous because the water and electrolyte loss can lead to dehydration. This can also increase the chances of malnutrition and weight loss. Short bowel syndrome may also include the following symptoms:
- loss of appetite
- weight loss
- nausea and vomiting
- stool with an especially foul odor
- kidney stones or gallstones
- bacterial overgrowth
People with short bowel syndrome may also have specific nutrient deficiencies in certain vitamins, depending on which section of the small intestine was damaged or removed in surgery. Such deficiencies may lead to additional symptoms like anemia, muscle spasms, easily bruised skin, and problems with blood clotting after an injury. Short bowel syndrome patients are also more likely to develop food allergies; one example is lactose intolerance, an inability to digest the enzyme lactose in milk and other dairy products.
What Causes Short Bowel Syndrome?
Apart from the rare case of a person being born with a shorter small intestine, the most common cause of short bowel syndrome is surgery or intestinal damage. Surgery on the small intestine— also referred to as small bowel resection—can be used to treat a wide variety of conditions, including injuries, digestive diseases, or birth defects. Below are some of the reasons for resection surgery that might lead to short bowel syndrome:
- Crohn’s disease: One of the two main types of inflammatory bowel disease, Crohn’s disease is a condition in which chronic inflation of the intestines can cause permanent scarring damage.
- Cancer: Both damage due to the growth of cancer cells and the treatment for cancer in the small intestine can cause damage that can only be remedied through surgery.
- Necrotizing enterocolitis: Surgery to correct necrotizing enterocolitis is the most common cause of short bowel syndrome in infants.
- Intussusception: This condition involves one part of the intestine becoming folded into another part and subsequent problems with blood flow to intestinal tissues.
- Injury: Any kind of injury to the small intestine can cause significant problems such as twisting (volvulus), blocked blood vessels, or trauma.
Diagnosis and Treatment for Short Bowel Syndrome
Because diarrhea and other symptoms of short bowel syndrome are common to many other gastrointestinal conditions, you will likely not know or suspect you have it until a doctor has diagnosed it. Even if you have already had a small bowel resection, the diagnosis will typically involve a blood test, fecal fat test, and imaging tests of the abdominal area; examples of imagine tests the doctor may use include X-ray, computerized tomography (CT scan), or an upper GI series. Once a diagnosis is confirmed, there are four components of treatment that can be used:
- Nutritional support: The first order of treatment for small bowel syndrome is to make nutritional changes. This can involve oral rehydration, vitamin and mineral supplements, and dietary modification. In some cases it can also involve providing extra nutrients through an intravenous line (total parenteral nutrition) or a feeding tube (enteral nutrition).
- Medication: Various medications may be prescribed to treat the symptoms, including antibiotics, H2 blockers, and proton pump inhibitors. The doctor may also prescribe growth hormones or drugs like teduglutide that can help improve the intestinal absorption of nutrients.
- Surgery: If other interventions don’t work, there are surgical options that can also improve intestinal absorption, narrow any enlarged sections of intestine, or slow down bowel motility.
- Intestinal transplant: In extreme cases of intestinal failure, an intestinal transplant may be necessary, especially when a patient is totally reliant on feeding tubes. A transplant requires a donor to provide a section of their small intestine.
Be Mindful of Digestive Health
Short bowel syndrome is a fairly rare condition that typically only affects those who previously have had surgery on their small intestine. The symptoms of the condition, though, are common to many other kinds of gastrointestinal problems. If you have been having symptoms you can’t explain, you may want to seek advice from a healthcare professional for your own peace of mind or to increase your quality of life. If you would like to speak with a qualified gastroenterologist, please contact us at Cary Gastro to request an appointment.