Stagnant Syndrome / Blind loop syndrome
Most adults have nearly 30 feet of intestine; the absorptive area of the small intestine alone is about the size of a tennis court. Given the length and complexity of the intestinal tract, it's not surprising that the course of digestion doesn't always run smoothly. A case in point is blind loop syndrome — sometimes called stasis syndrome — which occurs when part of the small intestine is bypassed and so cut off from the normal flow of food and digestive juices.
The bypassed portion of intestine, known as a blind loop, initiates a cascade of problems. Food can't pass through the loop and so begins to ferment, encouraging the rampant growth of bacteria. The bacteria then interfere with the absorption of essential nutrients, often leading to diarrhea, weight loss and malnutrition.
Blind loop syndrome occurs most often as a complication of abdominal surgery, but blind loop syndrome can also result from structural defects and some diseases. Although blind loop syndrome occasionally requires surgical treatment, most people respond well to antibiotic therapy.
Although digestion begins in your mouth, the real work of breaking down and absorbing nutrients takes place in your small intestine, the longest section of the digestive tract. Connecting the stomach and large intestine, the small intestine is where food mixes with digestive juices from the pancreas, liver and gallbladder, and where small molecules of nutrients — amino acids from proteins, monosaccharides from carbohydrates and most fats — are absorbed into your bloodstream.
Unlike the large intestine, which has millions of bacteria to help break down indigestible fiber, the small intestine normally
contains relatively few microorganisms. Because the small intestine is rich in enzymes, it doesn't need the enzymatic action of bacteria; in fact, stomach acid and secretions from the liver and pancreas actually act as antibacterial agents. What's more, the strong muscular contractions (peristalsis) that propel food through the small intestine prevent bacteria from colonizing there.
But in blind loop syndrome, food can't move through the bypassed section of bowel, and the stagnant food becomes an ideal breeding ground for microorganisms — a condition called bacterial overgrowth syndrome. A healthy person might have 10 to 1,000 bacteria in a given area of the small intestine, whereas someone with blind loop syndrome is likely to have to have many times more. The bacteria often produce toxins as well as interfere with the absorption of nutrients.
What triggers blind loop syndrome
The term "blind loop syndrome" dates back to the turn of the 20th century, when doctors noticed that some people developed diarrhea if part of the bowel were bypassed as a result of surgery or trauma. A century later, those observations still hold true.
Most often, a blind loop is an inadvertent consequence of gastric surgery, such as Billroth II or Roux-en-Y procedures for ulcers and gastric bypass surgery for obesity. Operations on the small intestine and structural abnormalities sometimes can cause blind loops as well. And a number of medical conditions can lead to bacterial overgrowth, including Crohn's disease and scleroderma and diabetes, which can slow the rate at which food moves through the intestine.
Risk Factor :
You're more at risk of blind loop syndrome if you've had gastric surgery for ulcers or obesity. Other factors that make you more susceptible to the disorder include :
- A structural defect in the small intestine
- Crohn's disease, intestinal lymphoma, scleroderma or diabetes
- Diverticulosis of the small intestine, a condition in which small pouches of tissue protrude through the intestinal wall
- Injury to the small intestine from radiation treatments (radiation enteritis)
When to seek medical advice :
Bloating, nausea and diarrhea are symptoms of many intestinal problems, ranging from irritable bowel syndrome to "stomach flu" (gastroenteritis), and for the vast majority of people, they aren't an indication of blind loop syndrome. But if you have persistent diarrhea or rapid, unintentional weight loss, it's important to see your doctor for a full evaluation.
Because blind loop syndrome affects digestion and absorption, signs and symptoms of the disorder often include :
- Loss of appetite
- Abdominal pain
- Diarrhea or steatorrhea — frothy, foul-smelling stools indicating poor fat absorption
- An uncomfortable feeling of fullness after eating
- Fatty stools
- Unintentional weight loss
The first step in diagnosing blind loop syndrome is usually an abdominal X-ray or an abdominal computerized tomography (CT) scan, an X-ray technique that produces more detailed images of the body than conventional X-rays do.
You may also have additional tests to check for bacterial overgrowth in the small intestine, for poor fat absorption or for other problems that may be causing or contributing to your Symptoms:
- Barium X-ray of the small intestine. This test uses a contrast dye (barium) to coat the lining of your intestine so that it stands out clearly on X-rays. A barium X-ray may reveal a blind loop, diverticulosis, a narrowing (stricture) of the intestine or other anatomical problems as well as slow transit times that can cause bacterial overgrowth.
- Hydrogen breath test. Several breath tests are used to check for bacterial overgrowth. Because fermenting carbohydrates release hydrogen, this test measures the amount of hydrogen in your lungs after you drink a mixture of glucose and water. Hydrogen levels are checked at 15- to 30-minute intervals over a 2- to 3-hour period. A rapid rise in hydrogen indicates poor carbohydrate digestion and bacterial overgrowth in your small intestine. Although widely available, the test is less sensitive than other breath tests are.
- C-D-xylose breath test. In this test, which is more accurate than a hydrogen breath test, you ingest a type of sugar called xylose. If unusual numbers of bacteria are present in your small intestine, they metabolize the xylose, releasing carbon dioxide in the process. Breath carbon dioxide is measured every half hour and usually peaks about two hours into the test.
- Bile acid breath test (14-C glycocholate). In the small intestine, bile acids from the liver help emulsify and digest fats (lipids). But proliferating bacteria interfere with this process, leading to poor absorption of both fats and carbohydrates. This test uses a bile salt (glycocholate) bound to a small amount of radioactive material to check for bile salt dysfunction in your small intestine.
- Quantitative fecal fat test. This test may be used to determine how well fats are absorbed. Most often, you eat a high-fat diet for three days. The amount of fat in your stool is then measured. Large amounts of undigested fat indicate malabsorption, one cause of which is bacterial overgrowth.
- Small intestine aspirate and fluid culture. This is the most sensitive test for bacterial overgrowth, but it's invasive and technically difficult to perform. To obtain the fluid sample, doctors pass an endoscope down your throat and through your digestive tract to the small intestine. A sample of intestinal fluid is withdrawn with the endoscope and then placed in a culture medium in a laboratory where it's observed for the growth of bacteria.
A blind loop can trigger an escalating series of problems, including :
- Poor absorption of fats. Because bacteria in the small intestine break down (deconjugate) the bile salts needed to emulsify and digest fats, the fat in food as well as the fat soluble vitamins A, D, E and K aren't well absorbed. This leads to diarrhea and often to steatorrhea — fatty, foul-smelling stools — as well as to weight loss and vitamin deficiency disorders. A lack of vitamin A can cause night blindness, for example, and low levels of vitamin D affect the body's ability to absorb calcium, which can lead to weakened bones. The problem of calcium malabsorption is compounded when bacterial overgrowth damages vitamin D receptors in the small intestine.
- Damage to the intestinal lining. Bacterial overgrowth harms the mucous lining (mucosa) of the small intestine both directly and indirectly. Toxic byproducts that are released when bacteria break down stagnant food damage the mucosa, as do bacterial enzymes themselves. This damage means that most nutrients, including carbohydrates and proteins, are poorly absorbed, leading to serious nutritional deficiencies.
- Vitamin B-12 deficiency (macrocytic anemia). Vitamin B-12, which is essential for the normal functioning of your nervous system and the production of blood cells and DNA, is absorbed in the small intestine. But proliferating bacteria actually use up the vitamin, reducing the amount that's available to your body. A severe deficiency can lead to weakness, fatigue, tingling and numbness in your hands and feet, and, in advanced cases, to mental confusion. Damage to the central nervous system resulting from a B-12 deficiency may be irreversible.
- Iron deficiency. You may have low iron levels if the part of the small intestine where iron is absorbed is bypassed or you have bleeding ulcers in the bypassed portion of your bowel.
- Brittle bones (osteoporosis). Both calcium and vitamin D, which aids in calcium absorption, are metabolized in the small intestine. But damage to the intestine from abnormal bacterial growth causes poor calcium absorption and eventually may lead to bone diseases such as osteopenia, osteoporosis and osteomalacia, a softening of the bones that results from low levels of vitamin D.
Whenever possible, doctors treat blind loop syndrome by dealing with the underlying problem — surgically repairing a postoperative blind loop or stricture, for example. But often, the blind loop can't be reversed. In that case, treatment focuses on correcting nutritional deficiencies and eliminating bacterial overgrowth.
For most people, the best way to treat bacterial overgrowth is with antibiotic therapy, and doctors may start this treatment even when test results are inconclusive. A short course of antibiotics often significantly reduces the number of abnormal bacteria, but because bacteria can return when the antibiotic is discontinued, the therapy may need to be long term.
Doctors also may switch among different drugs to help prevent bacterial resistance. Ironically, because antibiotics wipe out most intestinal bacteria — both normal and abnormal — they can cause some of the very problems they're trying to cure, including diarrhea and an imbalance of bacteria in the digestive tract.
Addressing nutritional deficiencies is a crucial part of treating blind loop syndrome, particularly in people with severe weight loss. But although malnutrition can be treated, the damage it causes can't always be reversed.
These measures may improve vitamin deficiencies, reduce intestinal distress and help with weight gain :
- Nutritional supplements. People with blind loop syndrome need intramuscular injections of vitamin B-12 as well as oral vitamin and iron supplements.
- Lactose-free diet. Damage to the intestine can cause some people to lose the ability to digest milk sugar (lactose). In that case, it's important to avoid most lactose-containing products, including milk and cheese. Some people may tolerate yogurt because the bacteria used in the culturing process naturally breaks down lactose.
- Medium-chain triglycerides. Trigylcerides are a type of fat consisting of a molecule of glycerol to which three hydrocarbon chains are attached. The chains vary in length, and the way your body processes triglycerides depends on the length of the chains. Most dietary fats are long-chain triglycerides, containing 14 to 22 carbon atoms. Food sources include many vegetable oils and animal fats, all of which are emulsified and absorbed in the small intestine. On the other hand, medium-chain triglycerides, found in coconut oil, are absorbed without the aid of digestive enzymes. Because they're more readily digested by people with blind loop syndrome, medium-chain triglycerides are sometimes prescribed as a dietary supplement.
|Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.