What is Short Bowel Syndrome?
The small intestine in an adult, starting from where it joins the stomach, is usually between 275 to 850 centimeters long. It handles around 9 liters of liquid every day, including drinks, saliva, and digestive juices. Out of these, the small intestine absorbs about 7 liters and the large intestine absorbs about 2 liters. A healthy large intestine absorbs about 150 calories on average per day, but it can absorb up to 1000 calories in patients with digestion issues.
Most nutrients are absorbed in the first 100 centimeters of the small intestine, while vitamin B12 and bile salts are absorbed in the last 100 centimeters. The final section of the small intestine and the beginning of the large intestine is where magnesium is absorbed; whereas, water and sodium are absorbed throughout the intestines.
The condition known as short bowel syndrome (SBS) in adults occurs when less than 180 to 200 centimeters of the small intestine remain, resulting in the need for food and fluid supplements. While there’s no widely accepted definition for SBS in children, it’s thought to exist when less than 25% of the expected small intestine length remains for the child’s age, leading to the need for supplements through veins.
About 75% of SBS cases occur after a large section of the intestine is removed in a single surgery, while the rest typically happen after several smaller surgeries. About two-thirds of SBS patients survive their first hospital stay, and a similar proportion also survive the first year. A patient’s age and underlying health conditions usually determine their long-term outlook.
What Causes Short Bowel Syndrome?
Short bowel syndrome (SBS) can occur from major surgery where a large part of the intestine is removed, or from birth defects affecting the intestine. In adults, SBS is often caused by conditions such as Crohn’s disease, blocked or reduced blood supply to the intestines (mesenteric ischemia), damage caused by radiation treatment (radiation enteritis), scar tissues that form after surgery (post-surgical adhesions), and complications after surgery.
For children, common causes of SBS include twisting of the intestines (volvulus), problems with how the intestines are formed (intestinal malformations), and a serious intestinal disease common in premature babies called necrotizing enterocolitis.
Risk Factors and Frequency for Short Bowel Syndrome
The understanding of Short Bowel Syndrome (SBS) is still not complete because there aren’t enough statistics regarding the number of people who experience intestinal failure due to SBS.
Signs and Symptoms of Short Bowel Syndrome
Short bowel syndrome (SBS) is a condition characterized by poor absorption of nutrients due to a decrease in the area of the intestine that absorbs nutrients and fast movement of food through the intestines. This can lead to a variety of health issues such as:
- Malnutrition
- Weight loss
- Diarrhea
- Steatorrhea (fatty stool)
- Dehydration
- Vitamin deficiencies
- Imbalance of electrolytes
People with SBS usually have a history of extensive small intestine surgery due to various health conditions.
Treatment Options for Short Bowel Syndrome
When managing Short Bowel Syndrome (SBS), the aim is to support good nutrition, maximize absorption from the remaining part of the small intestine, and prevent complications. This starts with providing nutrition directly into the bloodstream after surgery, and later, when the patient has recovered from the surgical shock (ileus), they can start receiving nutrition through the normal digestive tract. This helps the intestine adapt and improve nutrient absorption over time.
If a patient’s intestinal failure is permanent, they will need ongoing nutrition provided directly into their bloodstream at home or an intestine transplant if a life-threatening complication arises. Treatment mostly involves managing and preventing complications due to SBS or the use of nutrition provided directly into the bloodstream at home.
Certain conditions linked with intestinal failure, like liver disease and issues with the flow of bile (cholestasis), can be treated by maintaining some normal food intake, treating infections or inflammations promptly, fine-tuning the nutrition provided directly into the bloodstream, reducing the use of soy-based fat emulsions (or switching to fish oil-based ones), and certain surgical procedures not involving transplants.
Patients with SBS who have less than 180 centimeters of small intestine or are missing a particular valve (ileocecal valve) are at a heightened risk of developing gallstones, particularly consisting of calcium bilirubinate. These gallstones can be prevented or reversed by ensuring they get nutrition through the normal digestive route as much as possible, limiting periods of fasting, and cutting back on certain medications like narcotics and anticholinergics. Conditions like dehydration, low sodium levels in the blood, chronic kidney failure, and kidney stones due to SBS are managed by providing fluids intravenously to maintain normal hydration and urine production.
Low magnesium levels can occur due to poor absorption because of loss of certain parts of the intestine, or calcium binding to fatty acids making it unavailable. The treatment includes proper hydration and magnesium supplementation. A particular type of acidity in the blood (D-lactic acidosis) can arise in patients with SBS due to the breakdown of non-absorbed carbohydrates by gut bacteria. This could lead to a variety of neurological symptoms, including speech defects, unsteady gait, altered mental state, psychosis and, in severe cases, coma. Treatment involves stopping the feeds with carbohydrates, administering antibiotics active against D-lactate forming bacteria, hydrating properly, and giving thiamine supplements.
Almost all patients on prolonged home-based nutrition directly in the bloodstream develop a metabolic bone disease causing bone thinning (osteopenia, osteomalacia, or osteoporosis). This can be diagnosed and evaluated through tests like bone mineral density, serum and urine mineral levels, vitamin D, PTH, and markers of bone turnover. The management includes lifestyle and dietary changes, treatment of the underlying disease, optimization of vitamin D status and nutrition directly into the bloodstream, sometimes also including bisphosphonates (bone-strengthening drugs).
Surgery is another essential treatment strategy for patients with SBS. Those reliant on nutrition provided directly into the bloodstream and suffering from rapid food transit may benefit from surgeries that realign the intestine or insert segments of the colon into the small intestine. Those with less than 60 centimeters of small intestine and complications related to the nutrition provided directly into the bloodstream might be eligible for intestine transplantation. If there’s bowel distension due to obstruction, this can sometimes be managed with surgical narrowing or creation of intestinal passages, depending on the size of the remaining intestine.
What else can Short Bowel Syndrome be?
- Excessive Growth of Antral G Cells
- Decay of the Stomach Lining (Atrophic Gastritis)
- Blockage of the Stomach Outlet
- Gastrin-Producing Tumor (Gastrinoma)
- Past Vagus Nerve Interruption (Vagotomy)
- Kidney Failure
- Retained Antrum Syndrome (A Condition Related to Stomach Surgery)
- Short Gut Syndrome (Insufficient Small Intestine)
What to expect with Short Bowel Syndrome
People with more than 180 cm of small bowel usually do not need parenteral nutrition, a special diet given through a vein. Those with more than 90 cm of small bowel tend to need this type of nutrition for less than a year. However, individuals with less than 60 cm of small bowel are likely to require parenteral nutrition for their entire life.
Possible Complications When Diagnosed with Short Bowel Syndrome
Problems with absorbing nutrients, also known as malabsorption, could lead to several health issues. These include, but are not limited to, malnutrition, weight loss, greasy stools, diarrhea, and an imbalance of essential body salts and vitamins.
Additional complications can occur, such as:
- Kidney stones due to higher levels of oxalic acid in the urine
- Gallstones
- Excess stomach acid
- Too many bacteria in the gut
- Dehydration
- Low sodium and potassium levels
- Deficiency in magnesium
- Kidney failure
- Calcium-oxalate kidney stones
- Cholestasis, or congestion of the bile duct due to a liver disease associated with intestinal failure
- High acid levels in the blood
In adults and older kids, the accumulation of fat in the liver, or steatosis, is more common. On the other hand, infants often experience cholestasis and a rapid development of liver scarring. Deaths associated with a liver disease due to intestinal failure are seen in about 16% to 60% of infant deaths in those on home nutritional feeding via a vein.