The small intestine, also called the small bowel, is part of the digestive tract. This organ connects the stomach and the large intestine and is the longest part of the digestive system. A number of conditions can interfere with digestion and affect the small intestine. Pain, bloating, constipation, and diarrhea may occur as symptoms of these disorders.
As food being digested travels through it, the small intestine absorbs vitamins and minerals. Problems with the small intestine can cause not only discomfort but also nutritional problems, and this can affect the rest of the body.
Diseases and conditions that can affect the small intestine include Crohn’s disease, celiac disease, small intestinal bacterial overgrowth (SIBO), and irritable bowel syndrome (IBS).
When food is chewed and swallowed, it goes down the esophagus (food tube) into the stomach, and then into the small intestine. It travels through the three parts of the small intestine—the duodenum, jejunum, and ileum. The muscles in the walls of the small bowel move the food along while it is digested and vitamins and minerals are absorbed.
Several problems can occur in the small intestine and affect how well it digests food.
1. Crohn’s Disease
2. Celiac Disease
3. Irritable Bowel Syndrome
4. Obstruction
5. Small Intestine Bacterial Overgrowth (SIBO)
Crohn’s disease is one form of inflammatory bowel disease (IBD). It can affect the small intestine as well as the rest of the digestive tract. It causes inflammation in the lining of the walls of the gut. This can lead to ulcers. Other problems that can occur in the digestive tract include pain, diarrhea, constipation, and not digesting food well.
Crohn's disease symptoms may include:
1. Diarrhea
2. Blood in the stool
3. Abdominal pain
4. Reduced appetite
5. Weight loss
Outside of the gut, there can also be problems with the eyes, skin, mouth, and joints. You may also experience whole-body symptoms like fever and fatigue.
Celiac disease is an autoimmune disease. When you have an autoimmune disease, your immune system mistakenly attacks your own body.
Celiac disease affects the small intestine. The lining of the small bowel is covered in villi, which are like little fingers. The villi absorb nutrients from food.
When a person with celiac disease eats gluten, white blood cells attack the villi, which then become worn down. This leaves the small intestine less able to absorb vitamins and minerals from food.
Some people may experience no symptoms, but for those who do, symptoms include:
1. Nausea and vomiting
2. Chronic diarrhea or constipation
3. Gas and bloating
4. Abdominal pain
5. Greasy stools that smell bad
6. Lactose intolerance
7. Weight loss
There can also be signs in other parts of the body that include anemia (lack of healthy red blood cells), joint pain, fatigue, or other problems, especially in adults.
IBS is a common condition that can affect the intestines.It can cause:
1. Constipation or diarrhea
2. Abdominal pain
3. Gas and bloating
The symptoms can be bad enough to interfere with daily life, such as going to school or work and socializing.
A small intestine obstruction or blockage means that there is something blocking food from going through. This can happen as a result of another condition, such as Crohn’s disease. Inflammation can cause the bowel to become blocked or lead to scar tissue that thickens the walls of the intestine.
Food can become stuck if there is a condition that causes the small bowel to move food too slowly (called motility disorders).
Symptoms of obstruction include:
1. Severe abdominal pain or cramping
2. Constipation
3. Vomiting
4. Abdominal fullness or swelling
5. Feeling like you need to pass gas but can't
A bowel obstruction can be an emergency. Blockages might be treated with medication and fluids in the hospital. In serious cases, surgery might be needed.
The small and large intestines are normally home to microorganisms (gut flora), which are essential to their function. The bacteria can get out of balance and overgrow.
1. Gas and bloating
2. Constipation or diarrhea
3. Weight loss
The condition can also cause other symptoms outside the digestive system such as fatigue and weakness.
SIBO can be difficult to diagnose and treat. It might be associated with other conditions such as IBS, diabetes, or autoimmune conditions.
When problems in the small intestine start, the signs and symptoms might not seem related to digestion. In some cases, it might take time and a healthcare provider who is good at diagnosing to get to the heart of the matter.
Some of the tests that might be used to find problems in the small intestine include:
1. Barium swallow and small bowel follow-through:In this test, X-rays are taken after drinking a contrast solution (barium) to see the esophagus, stomach, and small intestine.
2. Blood tests:Blood tests won’t be used to make a diagnosis, but they can find problems such as anemia or vitamin deficiencies.
3. Colonoscopy:A colonoscopy is used to find problems with the colon (large intestine) rather than the small intestine, but this test might be used to rule out other digestive conditions.
4. Computed tomography (CT) scan:This is a type of X-ray that takes detailed images of internal organs in the abdomen.
5. Magnetic resonance imaging (MRI):This test uses a strong magnet to scan the abdomen and provide images.
6. Endoscopy:A small tube with a light and camera on the end is inserted into the mouth and down the esophagus to the stomach and the first part of the small intestine. A biopsy (a piece of tissue or fluid) might be removed to be tested.
7. Breath testing:A breath test may diagnose or rule out small intestine bacterial overgrowth.
8. Stool tests:To rule out problems like an infection, stool might be sent to a lab for testing, which may include a bacterial culture.
9. Ultrasound:This test uses sound waves to see the organs and structures in the abdomen.
The treatment for small bowel conditions will be different based on what’s causing them. However, part of treatment might include lifestyle changes such as nutrition and diet, stress reduction, or working with a mental health professional.
The treatment for celiac disease is avoiding gluten. There currently aren’t any medications to treat the condition, although there may be treatments for symptoms outside the digestive system.
For Crohn’s disease, treatment requires lifestyle changes as well as medications. In some cases, such as when the bowel becomes narrowed, surgery might be needed.
Lifestyle changes are also necessary for IBS treatment along with diet adjustments and medications. People with IBS may also work towards controlling symptoms by identifying what environmental triggers may set them off.
SIBO may be treated with antibiotics to curtail the growth of the bacteria. Other treatments could include getting any associated conditions under control, as well as nutritional support.
Bowel blockages might be treated in the hospital with decompression, which is done by inserting a flexible tube through the nose and down into the stomach. In some cases, surgery to remove the blocked section of the small intestine might be needed.
The small intestine is coiled inside the lower abdominal cavity beneath the stomach. The large intestine surrounds it, framing the edges of the abdominal cavity.
It looks like a long, pink or red tube with many folds. It’s about the width of your pointer finger. It’s the width that makes it “smaller” than the large intestine, not the length.
The small intestine absorbs nutrients and water from your food. If these functions are impaired, you may experience nutritional deficiencies and watery stools (diarrhea). The muscle movements of the small intestine help break food down and process it through your body. If these movements are impaired, you may experience indigestion and constipation. A variety of diseases and infections may cause inflammation of the small intestine, which can cause abdominal pain, nausea and vomiting.
The tube is lined with many layers of tissues and muscles. The tissues contain nerves, blood vessels, immune cells and lymphatic glands.