Short bowel syndrome

Overview

Short bowel syndrome (SBS) is a complex medical condition that arises when a significant portion of the small intestine is missing or non-functional, resulting in impaired nutrient absorption. The small intestine plays a critical role in digesting food and absorbing essential nutrients, fluids, and electrolytes. When the remaining length of the bowel is insufficient, patients may experience malnutrition, dehydration, and other serious health issues. SBS may be present from birth (congenital) or occur following surgical removal of the small intestine due to various underlying diseases. It is considered a type of intestinal failure and often requires long-term nutritional support and careful management.

Causes

Short bowel syndrome typically results from extensive surgical resection of the small intestine, but it can also occur due to congenital defects. The most common causes include:

In Infants and Children:

• Necrotizing enterocolitis (NEC): A serious condition in premature infants causing intestinal tissue death

• Gastroschisis: A birth defect where the intestines develop outside the body, sometimes requiring resection

• Intestinal atresia: Congenital absence or narrowing of parts of the intestine

• Midgut volvulus: Twisting of the intestine that can cut off blood supply

In Adults:

• Crohn’s disease: Chronic inflammation that may necessitate multiple resections

• Mesenteric ischemia: Blockage of blood flow to the intestine leading to tissue death

• Trauma or injury: Severe abdominal injuries requiring surgical removal of damaged segments

• Cancer or tumors: Surgical removal of malignant parts of the intestine

Symptoms

The symptoms of short bowel syndrome depend on the length and part of the intestine that remains functional. The severity of symptoms also depends on whether the ileocecal valve and colon are intact. Common symptoms include:

• Chronic diarrhea

• Greasy, foul-smelling stools (steatorrhea)

• Weight loss and malnutrition

• Dehydration and electrolyte imbalances

• Fatigue and weakness

• Abdominal pain, bloating, and cramping

• Vitamin and mineral deficiencies (especially B12, iron, calcium, magnesium, and zinc)

In infants, failure to thrive, poor growth, and developmental delays may be observed. Some patients develop complications such as kidney stones, gallstones, and liver disease due to chronic parenteral nutrition (PN) use.

Diagnosis

Diagnosis of short bowel syndrome is based on medical history, symptoms, physical examination, and a range of tests to assess intestinal length and function. Key diagnostic methods include:

• Medical history and surgical records: Reviewing past intestinal surgeries and conditions leading to bowel loss

• Stool analysis: Evaluation of fat content and electrolyte loss

• Blood tests: To check for anemia, nutrient deficiencies, liver function, and electrolyte imbalances

• Imaging studies: CT or MRI enterography to assess remaining bowel and detect complications

• Upper GI series or small bowel follow-through: To visualize bowel length and structure

Diagnosis is confirmed when there is clinical evidence of malabsorption and the small intestine is less than 200 cm in length in adults (or proportionally short in children).

Treatment

The management of short bowel syndrome aims to improve nutrient absorption, reduce dependence on parenteral nutrition, and maintain quality of life. Treatment is multidisciplinary and may include:

Nutritional Support:

• Parenteral nutrition (PN): Intravenous delivery of nutrients, fluids, and electrolytes—often required in the early stages

• Enteral nutrition: Use of feeding tubes to deliver nutrients directly to the digestive tract, which helps preserve gut function

• Oral diet modifications: Frequent, small meals high in complex carbohydrates and low in fat; vitamin and mineral supplementation

Medications:

• Antidiarrheal agents: Loperamide or codeine to slow transit time and improve absorption

• Acid-reducing medications: Proton pump inhibitors (PPIs) to reduce gastric acid secretion

• Bile acid binders: To reduce diarrhea due to bile acid malabsorption

• Hormonal therapies: Such as teduglutide (a GLP-2 analog) to enhance intestinal adaptation and absorption

Surgical Interventions:

• Bowel lengthening procedures: Such as serial transverse enteroplasty (STEP) or longitudinal intestinal lengthening and tailoring (LILT)

• Intestinal transplant: Considered in severe cases where PN dependence leads to liver failure or life-threatening complications

Prognosis

The prognosis of short bowel syndrome depends on several factors, including the remaining bowel length, presence of the ileocecal valve, overall health, age, and response to therapy. Many patients, especially children, can achieve significant intestinal adaptation over time and reduce or eliminate the need for parenteral nutrition. This adaptation typically occurs over 1 to 2 years post-resection.

Patients who maintain a significant portion of the ileum and colon generally have better outcomes. However, complications such as catheter-related infections, liver disease from long-term PN, and chronic dehydration may impact prognosis. With advances in medical nutrition therapy, medications, and surgical techniques, long-term survival and quality of life have significantly improved for individuals living with SBS.