Short Bowel Syndrome

What short bowel syndrome is

The small intestine is normally about 3 to 8 meters (10 to 26 feet) long. It digests food and absorbs nutrients, water and electrolytes. Different parts do different jobs:

• the duodenum absorbs iron and calcium
• the jejunum absorbs most nutrients
• the ileum absorbs vitamin B12 and bile acids, and slows the passage of food
• the colon absorbs water and sodium and gets energy from fiber

Short bowel syndrome usually develops when less than about 200 cm (6.5 feet) of small intestine remains. How severe it is depends on how much bowel is left, which parts, whether the colon is still connected, and whether the remaining bowel is healthy.

When the gut cannot absorb enough to keep someone healthy without intravenous support, it is called intestinal failure. SBS is its most common cause.

Anatomy types

Causes

In adults

• Crohn's disease requiring repeated bowel resections
• Mesenteric ischemia: a blood clot or blockage in the bowel's arteries or veins
• Volvulus: twisting of the bowel that cuts off blood supply
• Trauma to the abdomen
• Cancer surgery and radiation enteritis
• Complications of surgery, including bariatric surgery

In babies and children

• Necrotizing enterocolitis, a bowel disease of premature babies
• Gastroschisis: bowel developing outside the abdomen
• Intestinal atresia: missing sections of bowel
• Malrotation with volvulus
• Hirschsprung disease affecting long segments

Symptoms

• Chronic diarrhea or high-volume stoma output, often watery and worse after eating or drinking
• Dehydration: thirst, dizziness, low urine output, kidney strain
• Weight loss and muscle wasting
• Fatigue and weakness
• Fatty, pale, foul-smelling stools (steatorrhea)
• Bloating, cramping and gas
• Deficiency symptoms: anemia, easy bruising, night blindness, bone pain, mouth sores, muscle cramps and tingling

In children, poor growth and delayed development are key concerns.

How it is diagnosed

The diagnosis is usually clear from the surgical history. Tests assess severity and complications:

• Blood tests: electrolytes, magnesium, kidney and liver function, blood count, iron, vitamins A, D, E, K and B12, zinc and other trace elements
• Measurement of fluid output and urine sodium, which shows how well the body is holding on to salt
• Imaging: small bowel contrast studies or CT to measure the remaining bowel and look for narrowing
• Bone density scans
• Breath tests or a trial of antibiotics for small intestinal bacterial overgrowth

Treatment

Care is best provided by a specialist intestinal rehabilitation or nutrition team.

Fluids

• Oral rehydration solution (ORS): a solution with a high sodium content (around 90 mmol per liter, such as a modified WHO formula) is absorbed far better than water. Your team will give you a recipe or product.
• Limit plain water, tea, coffee, juice and soda if you have a jejunostomy, because these low-sodium drinks pull salt into the bowel and increase output.
• Separate drinks from meals by about 30 minutes in many cases.

Diet

Diet depends on whether you have a colon:

Eat small, frequent meals, chew well and take any prescribed vitamin and mineral supplements, including vitamin B12 injections if the ileum has been removed.

Medicines

• Antidiarrheal drugs such as loperamide or codeine, taken before meals
• Acid-reducing drugs (proton pump inhibitors or H2 blockers), especially in the first months, as stomach acid is increased after resection
• Bile acid binders for diarrhea after ileal resection with the colon in place, used with caution
• Antibiotics for bacterial overgrowth
• Pancreatic enzymes in selected cases
• GLP-2 analogs such as teduglutide: a daily injection that helps the remaining bowel grow and absorb more. It can reduce or eliminate the need for IV nutrition in some people.

Parenteral nutrition

Many people, especially early on or with very little bowel, need parenteral nutrition (PN): liquid nutrition given through a central venous catheter, often overnight at home. Some need only IV fluids and electrolytes. The team works to reduce PN as the bowel adapts.

Surgery and transplant

• Bowel-lengthening operations such as serial transverse enteroplasty (STEP), mainly in children with dilated bowel
• Reconnecting a stoma to the colon if possible
• Intestinal transplant for people with life-threatening complications of PN, such as liver failure or loss of venous access

Intestinal adaptation

After surgery, the remaining bowel gradually adapts: the lining grows taller villi, the bowel widens and absorption improves. Most adaptation happens in the first 1 to 2 years, and eating food by mouth stimulates it. Children have a particularly good capacity to adapt.

Complications

• Dehydration and kidney injury
• Central line infections and blood clots from long-term IV access
• Liver disease linked to intestinal failure and PN
• Kidney stones (calcium oxalate) and gallstones
• Bone disease: osteoporosis and osteomalacia
• D-lactic acidosis: colon bacteria ferment sugars into a compound that causes confusion and slurred speech
• Small intestinal bacterial overgrowth
• Vitamin and mineral deficiencies, including B12, iron, zinc and fat-soluble vitamins

Outlook

Outlook has improved greatly with specialist teams, home PN and newer drugs. Many adults and most children with enough remaining bowel and a connected colon are eventually able to stop PN. People with very short bowel or an end jejunostomy may need IV support for life but can live active lives, travel and work with home PN.

Frequently asked questions

What causes short bowel syndrome?

In adults, it most often follows surgery to remove large parts of the small intestine for Crohn's disease, loss of blood supply to the bowel, twisting of the bowel, trauma or cancer. In children, common causes are necrotizing enterocolitis, gastroschisis, intestinal atresia and volvulus.

What are the symptoms of short bowel syndrome?

The main symptoms are heavy, watery diarrhea or high stoma output, dehydration, weight loss, tiredness, bloating, and fatty, foul-smelling stools. Over time, vitamin and mineral deficiencies can cause anemia, bone pain, night blindness, muscle cramps and tingling. Children may not grow normally.

What should you eat with short bowel syndrome?

It depends on your anatomy. Small, frequent meals, salty foods and oral rehydration solution instead of plain water help most people. With a colon, complex carbohydrates and a low-oxalate diet are advised. Without a colon, more fat and extra salt are fine. A specialist dietitian should tailor your plan.

Can short bowel syndrome be cured?

The lost bowel cannot be replaced, except by transplant. However, the remaining intestine adapts over 1 to 2 years, and with diet, fluids, medicines and drugs such as teduglutide, many people reduce or stop IV nutrition. Intestinal transplant is an option for a small number with serious complications.

Is short bowel syndrome life-threatening?

It can be if dehydration, malnutrition, central line infections or liver disease are not managed. With care from a specialist intestinal rehabilitation team, most people live for many years with a good quality of life, and children often improve markedly as they grow.