Short Bowel Syndrome: Signs, Symptoms, and Causes

Short bowel syndrome (SBS) happens when your small intestine cannot absorb enough nutrients and fluids from the food you eat. This can happen because part of the small intestine is missing, either from surgery or from a problem at birth.¹

Without enough working intestine, your body cannot get the nutrition, fluids, and vitamins it needs to stay healthy.^1,2

What is short bowel syndrome?

Your small intestine has 3 parts: the duodenum, the jejunum, and the ileum. Together, they absorb fluids, protein, carbohydrates, iron, fat, vitamins, and minerals from the food you eat. Short bowel syndrome develops when a large portion of this organ is missing or is not working the way it should.³

This is a rare condition, affecting between 10,000 and 20,000 adults and children in the United States.³

What causes short bowel syndrome?

Short bowel syndrome is most often caused by surgery to remove part of the small intestine, called a small bowel resection.^1,4

Common reasons for this surgery include:^1,5,6

• Crohn’s disease – Long-term inflammation can damage the intestine so much that a diseased section must be removed.
• Cancer – Removing a tumor, or damage from radiation treatment, can shorten the intestine
• Blocked blood flow – When blood supply to the intestine is cut off, a problem called mesenteric ischemia, the tissue can die and need removal
• Injury – A serious abdominal injury can damage enough of the intestine that surgeons must remove it

How short bowel syndrome affects your body

When a large part of the small intestine is missing, there is less surface area left to absorb nutrients. Many people with short bowel syndrome have also lost the valve that connects the small intestine to the colon, called the ileocecal valve. Without it, food moves through the digestive system faster, leaving less time for the body to absorb what it needs.⁴

Right after surgery, the stomach may also produce too much acid, which can make diarrhea worse and further limit how much the intestine absorbs.⁴

Digestive symptoms of short bowel syndrome

Because the body has trouble absorbing nutrients, short bowel syndrome causes several digestive symptoms, including:^1,2,5

• Diarrhea: loose or watery stool is one of the most common symptoms
• Greasy, foul-smelling stools: undigested fat in the stool can make it look oily and smell unusually strong
• Bloating and gas: extra fluid and undigested food in the intestine can cause a swollen, gassy feeling
• Abdominal pain: cramping or discomfort in the belly is common
• Fatigue: feeling unusually tired is often linked to poor nutrient absorption
• Weight loss: without enough nutrients, the body may lose weight even when eating normally

Signs of dehydration to watch for

Diarrhea and fluid loss can quickly lead to dehydration. Some signs of dehydration to watch for include:^1,5

• Dark urine or urinating less than usual: a sign the body is holding onto fluid
• Extreme thirst and a dry mouth: the body’s way of asking for more fluid
• Dizziness or feeling light-headed; this can happen when blood pressure drops from fluid loss, and may lead to fainting
• Sunken eyes or cheeks: a visible sign of significant fluid loss
• Skin that does not bounce back when pinched; doctors call this decreased skin turgor

Complications that can develop over time

Poor nutrient absorption can lead to vitamin and mineral deficiencies in the long term. These deficiencies can cause anemia, a low red blood cell count, and weak, brittle bones.¹ Some people also develop metabolic acidosis, a buildup of acid in the blood, or kidney stones.⁴

When absorption stays poor, other problems can follow:^1,2

• Dehydration and electrolyte problems: from ongoing fluid loss
• Malnutrition and vitamin or mineral deficiencies: including low red blood cell counts
• Bacterial overgrowth: too many bacteria growing in the small intestine
• Lactose intolerance: trouble digesting the sugar in milk
• Peptic ulcers: from excess stomach acid, often within 6 to 12 months after surgery
• Gallstones and kidney stones
• Weak or thinning bones: osteoporosis or osteopenia
• Liver disease
• Catheter-related problems: for people on long-term nutrition through a vein

Talk to your doctor

Short bowel syndrome can range from mild to severe, and symptoms look different for everyone. If you or your child have ongoing diarrhea, unexplained weight loss, or any signs of dehydration, contact a doctor. Severe dehydration can become a medical emergency, so do not wait to seek care if symptoms are severe.⁵

Doctors can run tests to find the cause of your symptoms and build a nutrition and treatment plan that fits your needs. You are not alone in managing this condition, and a care team can help you feel better day to day.