What Is Short Bowel Syndrome?

Definition

Short bowel syndrome (SBS) is a condition where the small intestine (small bowel) is shortened or not functioning well enough to digest and absorb sufficient nutrients or water for a person to maintain health.

What does the small intestine do?

The small intestine (small bowel) is the longest part of the gastrointestinal tract. It sits between the stomach and the colon. The functions of the small intestine are to move food along, digest it into a liquid and absorb nutrients and water before it passes into the colon.

The wall of the small intestine contains specialist cells, which are adapted to be able to absorb everything the body needs from food. This includes macronutrients (proteins, carbohydrates and fat), micronutrients (vitamins and minerals), and water. A healthy person's average length of a small intestine is between 275 and 850 cm.¹. It is designed to be this long to have enough time and surface area to absorb everything.

Causes of short bowel syndrome

Surgery on the small intestine

The most common cause of short bowel syndrome is surgery on the small intestine. Some people require surgery on their small intestine if it is damaged. The most common cause of damage is inflammatory bowel disease (e.g. Crohn’s), cancer or infection. For example, during surgery, it may be necessary to remove parts of the intestine to prevent cancer from spreading or to remove dead or damaged tissue. Hence, the patient will be missing parts of their small intestine.

Short bowel syndrome occurs in approximately 15% of people who have had part of their small intestine removed.¹ The majority of people with SBS have had a large amount of their small intestine removed or have had multiple surgeries.¹ In short bowel syndrome, the remaining small intestine is often shorter than 200 cm. Generally, the severity of SBS symptoms increases if the size of the removed small intestine increases.

Following small intestine damage

Short bowel syndrome can also occur if the small intestine is damaged enough to impair its ability to absorb the nutrients or water required for health. The damages that might cause SBS are as below: ²

• Mesenteric ischemia is a condition where the blood supply is interrupted enough to cause permanent damage to the intestine
• Cancer of the intestine
• Radiation damage
• Inflammatory bowel diseases such as Crohn’s disease.
• Traumatic injury
• Being born with short or damaged intestine (congenital – at birth)

Diagnosis of short bowel syndrome

Symptoms

Symptoms vary depending on how much of the small intestine is missing or damaged and which parts of the intestine are affected. These are some of the common symptoms of short bowel syndrome:

• Weight loss
• Diarrhoea
• Pale or greasy poo
• Stomach cramps or pain
• Tiredness

If a patient is deficient in a specific vitamin or mineral, they may have symptoms associated with a deficiency disorder.1 In the most serious cases, patients will have complete intestinal failure and will need to be admitted as an emergency in a local hospital.²

Many of the symptoms listed above can be associated with other conditions of the small intestines, such as inflammatory bowel diseases (Crohn’s and Ulcerative colitis) and infections. Therefore, a doctor may also consider these possibilities during diagnosis. If you are worried about your symptoms, please contact your local doctor to arrange an appointment.

Complications associated with short bowel syndrome

Some patients have complications associated with SBS as below:² 

• Liver failure associated with intestinal failure and parenteral nutrition
• Kidney stones and gallstones
• Long-term diarrhoea
• Long-term parenteral nutrition: patients with small intestines between 90 and 180 cm in length will often require parenteral nutrition for around a year. Lifetime parenteral nutrition may be required if the remaining small intestine is less than 60 cm³
• Metabolic bone disease
• Any enteral or parenteral feeding involves the risk of sepsis

Clinical assessment

A doctor will often ask questions about your symptoms and medical history. If you have had part of your small intestine removed, then it is likely that a doctor will be aware of the potential for short bowel syndrome occurring.

They will also perform a medical examination to make a diagnosis. This may involve listening to your abdomen with a stethoscope and looking for other signs of disease.

Imaging and lab tests

To investigate short bowel syndrome, a doctor may decide to order certain tests:

• Blood tests: to look for deficiencies in vitamins and minerals
• Imaging scans (X-ray, CT, MRI): to look for visible signs of disease or damage
• Fecal fat test: if you are not absorbing enough fat, it will be excreted in your poo

Treatments

Once a diagnosis of short bowel syndrome has been made, there are a few different ways in which to treat it.

Diet

As the main effect of short bowel syndrome is that nutrients and water aren’t absorbed sufficiently, patients may need to work closely with doctors and dietitians to optimise their diets to ensure they stay healthy. People with SBS need to be careful about what they eat and how much they eat to avoid symptoms and complications.

Dietary advice for people with SBS:

• Eating small meals more frequently
• Avoiding certain foods that are high in fat, sugar or fibre because they can worsen diarrhoea symptoms
• Drinking more water to avoid dehydration
• Taking recommended vitamin and mineral supplements if they have a deficiency 

Nutritional support

When the small intestine is short or not functioning, it needs to undergo a process called adaption to repair. Adaption is a process whereby the remaining intestine changes so it can absorb enough nutrients and compensate for the missing or non-functional intestinal sections.² To promote adaption, it is generally necessary to increase the quantity of food a patient consumes.²

If the patient is unable to consume sufficient calories through solid food, it may be necessary to use a feeding tube through the nose or the abdominal wall, directly into the small intestine (enteral nutrition). Some people will still not be able to absorb enough nutrients and it will be necessary to give it into a vein to bypass the small intestine (parenteral nutrition). Some patients will require long-term enteral or parenteral nutrition. The type and amount of nutrient support will depend on the severity of the symptoms.

Medications

The doctor may prescribe specific medicines to reduce SBS symptoms like diarrhoea and acid reflux to accelerate the intestinal healing process and help with nutrient absorption.

Surgery

Surgery may be required to repair and remove any damaged intestinal tissue. It may also be used to lengthen the small intestine or change the structure of the intestine so that it can absorb more nutrients. For some people, there is the option of an intestinal transplant.

Summary

Short bowel syndrome (SBS) is a condition caused by a short small intestine or a lack of functioning small intestine. It typically arises after surgery involving the removal of large sections of the intestine. It also occurs following a disease or damage to the intestine. The consequences of short bowel syndrome are that nutrients and water are not absorbed in sufficient quantities to maintain a person’s health. A patient with SBS may have symptoms of weight loss, diarrhoea, tiredness, and stomach pain. A doctor will examine a patient for signs of SBS and may request imagining, blood, or faecal tests to investigate further. People with SBS must be careful about what they eat to avoid symptoms and complications and to maintain a healthy intestine. Nutritional support, such as enteral or parenteral nutrition, is often provided to ensure patients receive sufficient nutrients and water if their small intestine cannot absorb them. A doctor and a nutritionist will decide the nutritional requirements and provide support depending on the severity of the disease. Sometimes, medications provide symptom relief. Surgery may be necessary for some patients. Complications associated with SBS include liver failure, kidney stones and gallstones. Contact your local healthcare provider if you have any concerns about your symptoms or need more information.